Citation
Bifunctional synzymes via alternating copolymerization

Material Information

Title:
Bifunctional synzymes via alternating copolymerization
Creator:
Vanderbilt, David Paul, 1954- ( Dissertant )
Butler, George B. ( Thesis advisor )
Battiste, Merle A. ( Reviewer )
Hogen-Esch, Thieo E. ( Reviewer )
Palenik, Gus J. ( Reviewer )
Goldberg, Eugene P. ( Reviewer )
Place of Publication:
Gainesville, Fla.
Publisher:
University of Florida
Publication Date:
Copyright Date:
1982
Language:
English
Physical Description:
x, 136 leaves : ill. ; 28 cm.

Subjects

Subjects / Keywords:
Copolymerization ( jstor )
Copolymers ( jstor )
Ethers ( jstor )
Flasks ( jstor )
Imidazoles ( jstor )
Monomers ( jstor )
pH ( jstor )
Polymerization ( jstor )
Precipitates ( jstor )
Solvents ( jstor )
Chemistry thesis Ph. D
Dissertations, Academic -- Chemistry -- UF
Enzymes ( lcsh )
Polymers and polymerization ( lcsh )
Genre:
bibliography ( marcgt )
non-fiction ( marcgt )

Notes

Abstract:
The synthesis, characterization and evaluation of bifunctional synthetic enzymes (synzymes) via alternating copolymerization was carried out. It was desired to obtain copolymers containing alternating placements of complementary functional groups to see if "cooperativity" between the groups (in the hydrolysis of ester substrates) could be greater than in a random copolymer containing the same groups. To this end, the following bifunctional alternating copolymers were synthesized: N-(3-vinyloxyethyl )imidazole -- N-hydroxymaleimide (53.), isoeugenol -- N-[2-(4-imidazolyl)ethyl] maleimide (59), and 2- propenyl phenol -- N-[2-(4-imidazolyl )ethyl] maleimide (60). These copolymers were evaluated as catalysts in the hydrolysis of p-nitrophenyl acetate (PNPA) or 2,4-dinitrophenyl benzoate (DNPB). No cooperativity between imidazole and hydroxamic acid or imidazole and phenol groups was observed in the hydrolysis of activated esters, leaving unresolved the premise that bifunctional alternating copolymers should make better catalysts than bifunctional random copolymers.
Thesis:
Thesis (Ph. D.)--University of Florida, 1982.
Bibliography:
Includes bibliographic references (leaves 131-135).
General Note:
Typescript.
General Note:
Vita.
Statement of Responsibility:
by David Paul Vanderbilt

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University of Florida
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University of Florida
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Copyright [name of dissertation author]. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Resource Identifier:
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09912027 ( OCLC )
ACA4673 ( NOTIS )

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BIFUNCTIONAL SYNZYMES VIA
ALTERNATING COPOLYMERIZATION







BY

DAVID PAUL VANDERBILT





















A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

1982



























To my parents:

John and Betty Vanderbilt

who made it all possible.

To my aunt and uncle:

John and Helene Taras

who instilled in me

an appreciation of chemistry.
















ACKNOWLEDGEMENTS

I would like to thank Dr. George B. Butler for the opportunity

to work under his tutelage for the past three years. His encourage-

ment and guidance is sincerely appreciated. I also thank the members

of my supervisory committee.

Special thanks are extended to Dr. Kurt G. Olson, Dr. Huey

Pledger, Jr., Dr. Roy King and Dr. Thomas Baugh for invaluable advice

and assistance. I also thank Ms. Patty Hickerson for the skillful

typing of this manuscript. I am especially indebted to my friends

outside of chemistry for keeping me sane.

Financial support for this work from the National Science Founda-

tion (Grant DMR 80-20206) is gratefully acknowledged.
















TABLE OF CONTENTS

PAGE

ACKNOWLEDGEMENTS . . . . . . . . ... . . . iii

LIST OF TABLES . . . . . . . ... . . . vi

LIST OF FIGURES. . . . . . . . . ... ...... vii

ABSTRACT . . . . . . . . ... . . . . . ix

CHAPTER

I. INTRODUCTION . . . . . . . ... . . 1

Kinetic Scheme for Esterolysis . . . . . . .. 1
Effective Binding. . . . . . . . ... ... 2
Chemistry at the Active Site-- Cooperativity . . . 4
Choice of Catalytic Functional Groups. . . . . . 7
Proposal of Research . . . . . . . . . 9

II. EXPERIMENTAL . . . . . . . . ... .. . . 12

General. . . . . . . . . . ..... 12
Solvents . . . . . . . ... . . . 13
Reagents . . . . . . . . . . . . 14
Maleimide and Maleamic Acid Synthesis .. . . . ... .14
Succinimides and Succinamic Acids. . . . . . ... 25
Vinyl Ethers . . . . . . . . . . . 28
Imidazole and Histamine Derivatives . . . . ... 31
Other Monomers . . . . . . . .... ..... 40
Homopolymers . . . . . . . . . . . 42
Copolymers . . . . . . . . . . . 46
Miscellaneous Reactions. . . . . . . . ... 54
Kinetic Measurements . . . . . . . ... 56

III. RESULTS AND DISCUSSION . . . . . . . ... 60

Imidazole --Maleimides . . . . . . . ... 62
Hydroxamic Acid -- Maleimides . . . . . . . 64
Carboxylic Acid --Maleimides . . . . . . . 67
Imidazole --Vinyl Ethers. .. . . . . . .69
Other Imidazole Monomers . . . . . . . ... 71










PAGE

Copolymerization of Maleimides with N-(B-Vinyloxyethyl)-
imidazole (28) . . . . . . . . . .. 75
Copolymerization of Fumaronitrile (45) and Diethyl-
fumarate (44) With N-(B-Vinyloxyethyl)imidazole (28) . 88
Copolymerization of Maleimide (16) With B-Vinyloxyethyl-
(imidazol-4ylmethyl)piperidinium Chloride (30). .... .90
Copolymerization of Maleimide (11) with 4-Allylimidazole
(38) . . . . . . . . . . . . 93
Homopolymers. . . . . . . . . . . . 93
Copolymerization of Propenylphenols With Maleic Anhy-
dride (47) and N-Ethylmaleimide (43). . . . . ... 98
Kinetic Studies With Imidazole, 50, and 53. .. .... .102
Kinetic Studies With Copolymers 59, 60, 62, 63 and 68
and Model Compound 26 . . . . . . . . .104
Conclusion .. . . . . . . . . .. . 112

APPENDIX: SELECTED 1H AND 13C NMR SPECTRA. . . . .. .. .114

REFERENCES. . . . . . . . . . . . 131

BIOGRAPHICAL SKETCH . . . . . . . .. . .136
















LIST OF TABLES


TABLE PAGE

I Functional Groups Involved in the Catalytic Action of
Some Hydrolytic Enzymes . . . . . . . . 8

II Hydrogenation of 4-Nitroimidazole (39). . . . ... 63

III Acylation of Histamine (20) with VOC-C1 . . . ... 73

IV Solubility of 53 in Salt Solutions. . . . . .. 84

V Copolymerization of B-Vinyloxyethyl(imidazol-4ylmethyl)-
piperidinium Chloride (30). . . . . . . ... 92

VI Copolymerization of 4-Allylimidazole (38) . . ... 94

VII Homopolymerization of N-(B-Vinyloxyethyl)imidazole (28) 97

VIII Properties of Copolymers 57 64. . . . . . ... 102

IX Esterolysis of PNPA with Imidazole, 50, and 53. .... .103

X Esterolysis of DNPB with 26, 59, 60, 62, 63 and 68. . 105















LIST OF FIGURES


FIGURE PAGE

1 Proton decoupled 13C NMR spectrum of copolymer 53 in
D20-HC1, 70C. . . . . . . . . ... ... 80

2 Off-resonance decoupled 13C NMR spectrum of copolymer
53 in D20-HC1, 600C. . . . . . . . . ... 82

3 Proton decoupled 13C NMR spectrum of copolymer 54 in
D20-HC1, 800C. . . . . . . . .... .89

4 Proton decoupled 13C NMR spectrum of copolymer 50 in
acetone-d6 . . . . . . . . . . ... 96

5 pH-rate profile for the esterolysis of DNPB using 59 0,
60 A and 62 [ as catalysts . . . . .... .107

6 Plot of nsp/C vs. C for copolymer 62, 0.02M Tris buffer,
p = 0.02 (KC1), pH = 9.5 .. . . . . . 110

7 pH-rate profile for the esterolysis of DNPB using 26 0
and 68 A as catalysts . . . . . . . . .111

8 1H NMR spectrum of N-(O-Vinyloxyethyl)imidazole (28)
in CDCI3 . . . . . . . . . ... 114

9 1H NMR spectrum of N-(6-Vinyloxyethyl)piperidine (29)
in CDC13 . . . . . . . . . . . .115

10 1H NMR spectrum of B-Vinyloxyethyl(imidazol-4ylmethyl)-
piperidinium Chloride (30) in D20. . . . . .. 116

11 1H NMR spectrum of N-[(Ethenyloxy)carbonyl]-H-imida-
zol-4-ethanamine (35) in CDC13 .. . ........117

12 1H NMR spectrum of 4-Allylimidazole (38) in CDC13 ..... .118

13 1H decoupled 13C NMR spectrum of Poly(N-Acetoxymale-
imide) (48) in CD3CN-(CHC12)2at 60 . . . . .119

14 1H decoupled 13C NMR spectrum of Poly(Phenyl N-Male-
imidyl Carbonate) (49) in CD3CN at 70C. . . .. .120


vii










FIGURE PAGE

15 1H decoupled 13C NMR spectrum of Poly[N-(4-Carbethoxy-
phenyl)maleimide] (51) in acetone-d6 at 500C. .... .121

16 1H NMR spectrum of N-(B-Vinyloxyethyl)imidazole-N-
Hydroxymaleimide alternating copolymer (53) in DMSO-
d6 at 1200C ... . . . ....... ... . 122

17 1H decoupled 13C NMR spectrum of N-(B-Vinyloxyethyl)-
imidazole-Diethylfumarate copolymer (56) in CDC13 . 123

18 H decoupled 13C NMR spectrum of Isoeugenol --Maleic
Anhydride copolymer (57) in acetone-d6 at 45"C. ... 124

19 1H decoupled 13C NMR spectrum of 2-Propenylphenol --
Maleic Anhydride copolymer (58) in DMSO-d6 at 1200C .125

20 H decoupled 13C NMR spectrum of Isoeugenol --N-[2-(4-
Imidazolyl)ethyl] maleimide copolymer (59) in DMSO-d6
at 1100C. . . . . . . . . . 126

21 1H decoupled 13C NMR spectrum of trans-Anethole--Maleic
Anhydride copolymer (61) in DMSO-d6 at 1100C. .... .127

22 1H decoupled 13C NMR spectrum of Isoeugenol --N-Ethyl-
maleimide copolymer (63) in DMSO-d6 at 1100C. .... .128

23 1H decoupled 13C NMR spectrum of 2-Propenylphenol --N-
Ethylmaleimide copolymer (64) in DMSO-d6 at 1100C . 129

24 1H decoupled 13C NMR spectrum of N-Acetoxymaleimide
cyclotrimer (65) in CD3CN at 700C . . . . .. 130
















Abstract of Dissertation Presented to the
Graduate Council of the University of Florida
in Partial Fulfillment of the Requirements for the
Degree of Doctor of Philosophy

BIFUNCTIONAL SYNZYMES VIA
ALTERNATING COPOLYMERIZATION

By

David Paul Vanderbilt

December 1982

Chairman: Dr. George B. Butler
Major Department: Chemistry

The synthesis, characterization and evaluation of bifunctional

synthetic enzymes (synzymes) via alternating copolymerization was

carried out. It was desired to obtain copolymers containing alternat-

ing placements of complementary functional groups to see if "coopera-

tivity" between the groups (in the hydrolysis of ester substrates)

could be greater than in a random copolymer containing the same groups.

To this end, the following bifunctional alternating copolymers

were synthesized: N-(B-vinyloxyethyl)imidazole-- N-hydroxymaleimide

(53), isoeugenol -- N-[2-(4-imidazolyl)ethyl] maleimide (59), and 2-

propenylphenol-- N-[2-(4-imidazolyl)ethyl] maleimide (60). These co-

polymers were evaluated as catalysts in the hydrolysis of p-nitrophenyl

acetate (PNPA) or 2,4-dinitrophenyl benzoate (DNPB). No cooperativity

between imidazole and hydroxamic acid or imidazole and phenol groups

was observed in the hydrolysis of activated esters, leaving unresolved










the premise that bifunctional alternating copolymers should make

better catalysts than bifunctional random copolymers.















CHAPTER I

INTRODUCTION

A great deal of attention has been given to the understanding of

the catalytic properties of enzymes.I Enzymes are globular proteins

(polyamino acids) which catalyze most of the chemical reactions in

living organisms. Recently, we have begun to understand the mecha-

nisms by which enzymes catalyze organic reactions in terms of the

transition state theory. As man's knowledge of enzyme mechanism has

grown, so too has his wish to synthesize artificial enzymes or "syn-

zymes." Synzymes have shown considerable utility as probes of enzyme

kinetics.2 These synthetic enzymes should emulate the desirable

characteristics of natural enzymes, i.e., show high selectivity and

high efficiency (rate enhancement) toward the substrate molecule. To

date, both characteristics have been incorporated into synthetic poly-

mers to some degree. As this work deals with the synthesis and eval-

uation of synzymes, a brief discussion of recent developments in the

field follows.

Kinetic Scheme for Esterolysis

Enzymes are capable of catalyzing a great variety of chemical

reactions; one of the most studied of these is the esterolysis (ester

hydrolysis) reaction. In general, the kinetic scheme for the hydroly-

sis of an activated ester by a catalyst can be represented as follows:2b









k
Cat + RCO2R' i Cat -RCO2R'

ka II
-1 I




k III kd
k I Cat-CR + OR kd- Cat + RCO2H

0 H20


where Cat is the catalyst, and RCO2R' is the ester substrate. Step I

represents an equilibrium between free catalyst and free substrate

and a catalyst-substrate complex or Michaelis complex. This step is

assumed to be rapid and reversible with non-covalent binding forces

holding the complex together. The actual hydrolysis steps then take

place via acylation of the catalyst (II) and subsequent deacylation

(IV). This pathway is believed to be important in the case where

the catalyst is a natural enzyme. Alternatively, acylation of the

catalyst may occur via a bimolecular reaction (III), in which no pre-

association of catalyst and substrate has taken place. This pathway

is followed in the case of small molecule catalysts and many synzymes.

Catalysis by a synzyme might follow both reaction pathways simultane-

ously.

Effective Binding

Effective binding between catalyst and substrate prior to the

acylation step plays a key role in providing high catalytic activity.

This pre-association step greatly increases the esterolysis rate by

increasing the concentration of substrate at the active site of the









catalyst. Furthermore, acylation can take place via an intramolecular

reaction (II) rather than by the much slower intermolecular pathway

(III). At least four types of binding forces have been identified in

the pre-association process: coulombic interactions, hydrophobic

interactions, hydrogen bond formation, and charge-transfer interac-

tions. The most important factor determining the catalyst's effec-

tiveness, however, is that the binding take place at a site which is

favorable for the subsequent acylation reaction to occur.

An example of coulombic interactions as the mode of polymer-sub-

strate binding has been demonstrated by Overberger and Maki.3 Poly[4

(5)-vinylimidazole-co-acrylic acid] (1), containing an excess of

acrylic acid units (53.7 mol%) and therefore having an excess of

anionic sites, hydrolyzed positively-charged 3-acetoxy-N-trimethyl-

anilinium iodide (ANTI) faster than neutral p-nitrophenyl acetate

(PNPA), which in turn was hydrolyzed faster than the negatively-

charged substrate 3-nitro-4-acetoxybenzoic acid (NABA).

0
y
x II
x OCCH


OH HN(CH3)3


1 ANTI

0 0
II II
OCCH COH
OCCH


NO2 NO2
PNPA NABA









This study also demonstrates a certain degree of selectivity shown by

the catalyst toward the substrate.

Favorable binding by hydrophobic interactions has been demon-

strated by Klotz and Stryker.4a They found that partially lauroylated

poly(ethylenimine) catalyzed the hydrolysis of PNPA at a faster rate

than did poly(ethylenimine) itself. Indeed, the most effective synzyme

studied to date is a dodecylated poly(ethylenimine) containing imida-

zole residues. This derivative was found to approach a-chymotrypsin in

catalytic activity.4b On the other hand, Overberger and Smith5 studied

the effect of varying the chain length of substrate (2) using poly(l-

butyl-5-vinylimidazole) (3) and poly(1-methyl-5-vinylimidazole) (4) as

catalysts.

CH3(CH2)nC02 ) 02H -Bu
_=> 071-Bu N N-Me
02N 2 3 4
n = 0, 5, 10, 16

It was found for both (3) and (4) that (2, n = 16) was hydrolyzed at a

faster rate than (2, n = 0).

Chemistry at the Active Site--Cooperativity

As we have seen above, in order to observe a significant rate en-

hancement in esterolysis reactions the substrate must first be bound

to the polymer near or at the active site. Only after complexation

has occurred do the actual hydrolysis steps take place. Synzyme es-

terolysis has been observed to proceed with or without a complexation

step. Studies with a-chymotrypsin (a serine proteinase consisting of

245 amino acid residues) have shown that a serine 0 anion is respon-

sible for catalytic acylation of substrate.1












/0 0
o .... H-N N...H-0-- -H....N N-H
S j== \ /" -0-(Ser 195)

Asp(102) His(57) Ser(195)

The serine hydroxyl group is activated for the acylation reaction
by the scheme shown above, dubbed a "charge relay system," in which

the imidazole moiety plays an integral role in lowering the activation

energy for catalysis. A variety of cooperative effects among the

functional groups responsible for catalytic action is common in natu-

ral enzymes. The synthetic chemist has also sought to take advantage

of cooperativity in order to produce more efficient synzymes. A good

example of bifunctional cooperation utilizing a molecular relay system

was demonstrated by Kunitake and Okahata. These workers found that

the rate of hydrolysis of PNPA was 1000 times faster using a terpoly-

mer N-phenylacrylohydroxamate : 4(5)-vinylimidazole : acrylamide (5)

compared with N-phenylacrylohydroxamate : acrylamide copolymer (6) as

catalysts.


Ph' 'OH









The acylation step was demonstrated to occur primarily via the

hydroxamate anion, which is known to be a highly nucleophilic species.

It is also known that decomposition of an acylhydroxamate is a slow

process; the fact that S is a much better catalyst than 6 implies that

imidazole is catalyzing deacylation of the acylhydroxamate intermedi-

ate either acting as a nucleophile or general base.

Another example of a bifunctional catalyst exhibiting coopera-

tivity is a 1:1.95 copolymer of 4(5)-vinylimidazole and p-vinylphenol

(7).7a This copolymer was 63 times as efficient as imidazole for the
hydrolysis of ANTI at pH 9.1, and 10.6 times as effective as imidazole

vs. PNPA at the same pH. Phenol, poly(p-vinylphenol), poly[4(5)-

vinylimidazole] and a 1:0.48 copolymer of 4(5)-vinylimidazole and p-

methoxystyrene gave no significant rate enhancement under the same

conditions.


1.95




N-i OH
H
7

This great rate enhancement was attributed to cooperativity be-

tween imidazole and phenolate ion, which might involve (i) phenol

anion acting as a general base assisting the decomposition of the

tetrahedral intermediate and/or (ii) the phenol anion activating a

neutral imidazole for nucleophilic attack on the substrate. Coopera-

tive interactions have been demonstrated in small molecules by Bender

et al.7b












N" N-C-U-H 0 0 CH

OR HN N C=O

OR


i ii

Polymer Configuration

Catalytic properties of polymers are influenced to a large extent

by the configuration (conformation) of the polymer in solution. Vinyl

polymers are rather flexible as compared with enzymes, i.e., they

usually lack specific secondary and unique tertiary structure. As a

result, synthetic polymers lack the specific binding pocket which is

typical of enzymes. Therefore, the catalytic efficiency of synzymes

will depend to a large extent on the pH, ionic strength and composi-

tion of the medium, distance of the catalytic group from the polymer

backbone, degree of dissociation of catalytic groups, and many other

considerations.

Choice of Catalytic Functional Groups

As we have seen above, combinations of cooperative and/or com-

plementary functional groups are necessary to achieve high catalytic

efficiency. Catalysis by hydrolytic enzymes is of the nucleophilic

and acid-base type. Table I contains a list of functional groups

which are directly involved in the catalytic action of some hydrolytic

enzymes.















TABLE I

Functional Groups Involved in the 2
Catalytic Action of Some Hydrolytic Enzymesa

Enzyme Functional Group


Serine protease

Chymotrypsin
Trypsin
a-Lytic protease
Elastase
Subtilisin


-OH(Ser),

N
H


(His), -COOH (Asp)


-SH(Cys), N (His)


N
/ (His), N H (His, protonated)

H H
-COOH (Glu), -CO0 (Asp)


-- 0 OH (Tyr), Zn2+


Papain


Ribonuclease


Lysozyme


Carboxypeptidase










Proposal of Research

As was stated previously, synthetic vinyl macromolecules con-

taining bi- or multi-functionalities have been studied in other

laboratories and have shown enzyme-like catalytic activity. These

studies have shown a cooperativity between the functionalities lead-

ing to a rate enhancement for esterolysis reactions. However, up to

this time, functionalities have been introduced into copolymers in

random fashion. This ensures a degree of cooperation between the

functionalities which is dependent on the degree of alternation (i)

or upon the conformation of the polymer chain (ii) as depicted below.






A A B A A B B









-B




It appeared to us that the degree of cooperativity between func-

tional groups could be maximized by preparing regular alternating co-

polymers. This would assure that each functional group of a given

type would be flanked on either side by a functional group of the

complementary type.









Fundamental to this proposed research is the selection of monomer
pairs which undergo regular alternating copolymerization under free-
radical conditions. This type of copolymerization is generally thought
to result from the formation of a 1:1 charge-transfer complex between
electron-rich (donor) and electron-deficient (acceptor) monomer pairs.
Some examples of monomer pairs which give regularly alternating co-
polymers include styrene -- N-phenylmaleimide,8 2-chloroethyl vinyl
ether-- maleic anhydride,9 styrene-- maleic anhydride,10 2-allyl
phenol --maleic anhydride,11 and 2-allylphenol -- N-phenylmaleimide.11
In these laboratories, the alternating copolymerization of N-phenyl-
maleimide and 2-chloroethylvinyl ether has been studied extensively
by Olson.12


O+ n



Cl 0 Cl




It was concluded in this study that the predominant propagation
mechanism is homopolymerization of a 1:1 donor-acceptor complex. An
excellent review of the role of the charge-transfer complex in alter-
nating copolymerization can be found in this work.12
Our goal of producing bifunctional synzymes via alternating co-
polymerization could be approached by at least two methods. The first
method, which we believed would result in fully functionalized copoly-
mer, is the direct polymerization of monomer pairs containing the









desired functional groups (or the desired functional groups in masked

or protected forms).


+ n
A B



The second method involves derivatization of a pre-existing alternat-

ing copolymer. This method suffers from the fact that polymers can be

difficult to functionalize completely and resultant difficulties asso-

ciated with characterization of a partially functionalized polymer.


-- n B
A X A X A B




We have approached the problem via both methods. Our initial

efforts were aimed at direct polymerization of appropriately substi-

tuted monomer pairs. Difficulty was encountered effecting copolymeri-

zation due to side reactions caused by one of the unprotected func-

tionalities. Hence, derivatization of a pre-existing alternating

copolymer was also attempted.















CHAPTER II

EXPERIMENTAL

General

Melting points were determined on a Thomas-Hoover Capillary

Melting Point Apparatus or a Fisher-Johns Melting Point Apparatus

and are given in degrees celsius (uncorrected). Pressures are ex-

pressed in millimeters (mm) of mercury. Elemental analyses were

performed by Atlantic Microlabs, Inc., Atlanta, Georgia, and

Schwarzkopf Microanalytical Laboratories, Inc., Woodside, New York.

Proton nuclear magnetic resonance (NMR) spectra (60 MHz) were

recorded on Varian A-60A or Jeol JNM-PMX-60 instruments. Carbon-13

NMR (25 MHz) and 100 MHz proton NMR spectra were recorded on a Jeol-

JNM-FX-100 spectrometer. Chemical shifts are expressed in parts per

million (ppm) on the 6 scale downfield from tetramethylsilane (TMS)

or sodium 2,2-dimethyl-2-silapentane-5-sulfonate (DSS) unless other-

wise indicated. In cases where no internal reference was added,

spectra were calibrated via a characteristic signal of the deuterated

solvent used.13 The solvent used and calibration information are

given in parentheses for each spectrum reported. Multiplicities of

proton and off-resonance decoupled carbon resonances are designated

as singlet (s), doublet (d), triplet (t), quartet (q), multiple (m),

or broad (br).









Infrared (IR) spectra were recorded on a Perkin-Elmer 281 spec-

trophotometer. Absorbances are expressed in wavenumbers (cm- ) using

polystyrene (1601 cm-1) calibration. Solid samples were run as a KBr

pellet; liquid samples were analyzed neat as a thin film between NaCl

plates. Absorption bands are assigned the classifications: weak (w),

medium (m), strong (s), very strong (vs), broad (br), and shoulder (sh).

Low resolution mass spectra (LRMS) and high resolution mass spec-

tra (HRMS) were recorded on an Associated Electronic Industries (AEI)

Model MS-30 spectrometer.

Number average molecular weights (Mn) of polymers were determined

by vapor pressure osmometry (VPO) on a Wescan 233 Molecular Weight

Apparatus. Benzil was used as a calibration standard.

Intrinsic viscosities were measured with a Ubbelohde viscometer

(dilution viscometer).

Gel Permeation Chromatography (GPC) of polymers was carried out

on a Waters Associates- Liquid Chromatograph using glycerated porous

glass columns and both ultraviolet (UV) and differential refracto-

meter detectors.

Compound headings appear with the common name(s) listed first,

followed by the systematic name as found in Chemical Abstracts (CA).

CA registry numbers of known compounds are given in brackets.

Solvents

Deuterated NMR solvents were obtained from the Aldrich Chemical

Co. and Merck and Co., Inc. All solvents used for general applica-

tions were of Reagent grade or ACS grade quality. For special appli-

cations, solvents were distilled. Reference to a distilled solvent









in this chapter indicates that the solvent was purified in the manner

described below.14 Methanol was distilled from Mg(OCH3)2. Tetrahy-

drofuran (THF) was distilled from CaH2. Dimethylsulfoxide (DMSO) and

N,N-dimethylformamide (DMF) were allowed to stand over KOH and were

distilled from CaO. Dioxane was refluxed with aqueous HC1, dried over

KOH and distilled from sodium metal. Ethanol-free chloroform (CHC13)

was obtained by extraction of reagent grade CHC13 with conc. H2SO4 and

water, followed by distillation from P4H10. Dichloromethane (CH2C12)

was distilled from P4H10. Acetone was distilled from Nal.

Reagents

Starting materials and reagents were obtained from the following

suppliers: Aldrich Chemical Co., Fisher Scientific Co., Mallinckrodt,

Inc., Eastman Kodak Co., and Polysciences, Inc.

Maleimide and Maleamic Acid Synthesis

3,6-Endoxo-1,2,3,6-tetrahydrophthalic Anhydride/3a,4,7,7a-Tetrahydro-
4,7-epoxyisobenzofuran-1,3-dione [5426-0905] (8)

The following procedure was modified from the procedure of Narita

et al.15 To a 1 L three-necked round-bottomed flask equipped with a

mechanical stirrer and reflux condenser was added 109.2 g (1.604 mol)

of freshly distilled furan and 200 mL of benzene. The solution was

cooled via an external ice bath to 0-5C, after which 157.3 g (1.604

mol) of maleic anhydride was added portionwise. The ice bath was re-

moved after refluxing had slowed, and the mixture was stirred at room

temperature for 24 h. Additional benzene was added to facilitate

stirring. The mixture was filtered and dried in vacuo to give 235.9 g

(88.5%) of white crystalline product (8), mp 115-1160C (dec) [litera-

ture mp 118C (dec)].16









H NMR (DMSO-d6, TMS): 3.32 (s, 2H), 5.35 (s, 2H), 6.57 (s, 2H).

1C NMR (DMSO-d6, 39.5): 49.10, 81.75, 136.90, 171.53.

IR (KBr): 3195 (w), 3162 (w), 3136 (w), 3102 (w), 2995 (w), 1860

(s), 1787 (vs, br), 1640 (w), 1595 (w), 1567 (w), 1380 (w),

1321 (m, sh), 1310 (m), 1282 (m), 1242 (m, sh), 1230 (s), 1218

(s), 1193 (m), 1145 (m), 1086 (s), 1020 (s), 1000 (m), 950 (s),
920 (s), 903 (s), 878 (s), 848 (s), 820 (m), 798 (m), 731 (m),

689 (m), 672 (m), 633 (m), 620 (w).

N-Hydroxy-3,6-epoxy-1,2,3,6-tetrahydrophthalimide/3a,4,7,7a-Tetrahy-
dro-2-hydroxy-4,7-epoxy-1H-isoindole-1,3(2H)-dione [5596-17-8]
(9)
The following procedure was obtained from Narita et al.15 To a

1 L round-bottomed flask equipped with a mechanical stirrer and a

250 mL addition funnel was added 75.3 g (1.083 mol) of hydroxylamine

hydrochloride (dried in a vacuum oven at 600C overnight) and 400 mL

of freshly distilled methanol. After dissolution, the flask was

cooled to 0-5C. The addition funnel was charged with a solution of

60.8 g (1.083 mol) of potassium hydroxide in 150 mL of freshly dis-

tilled methanol and the solution added dropwise with vigorous stir-

ring. After addition, the mixture was stirred an additional 0.5 h,

and subsequently suction-filtered into a second 1 L three-necked

round-bottomed flask fitted with a mechanical stirrer and reflux con-

denser. To the stirring hydroxylamine solution was added portionwise

180 g (1.083 mol) of 3,6-endoxo-1,2,3,6-tetrahydrophthalic anhydride

(8). The mixture was refluxed for 8 h and then allowed to stir for

13 h at room temperature. The flask was cooled in an ice bath, and








the precipitate was filtered and dried in vacuo to yield 128.6 g

(65.5%) of white solid (9), mp 189-195C (dec) [literature mp 187-

188C (dec)].15

1H NMR (DMSO-d6, TMS): 2.86 (s, 2H), 5.13 (s, 2H), 6.53 (s, 2H).

1C NMR (DMSO-d6, 39.5): 43.91, 80.00, 136.24, 172.50.

IR (KBr): 3300 (s, br), 3095 (w), 3085 (w), 3050 (w), 3022 (m),

2998 (m), 1787 (s), 1730 (vs, br), 1567 (w), 1437 (s), 1338

(w), 1305 (m), 1283 (m), 1264 (m), 1240 (s), 1227 (m, sh), 1207

(m), 1196 (m), 1150 (s), 1089 (s), 1070 (m), 1010 (m), 951 (m),
916 (m), 881 (s), 846 (m), 823 (m), 803 (m), 792 (m), 720 (s),

644 (s).

N-Acetoxy-3,6-epoxy-1,2,3,6-tetrahydrophthalimide/2-(Acetyloxy)-3a,
4,7,7a-tetrahydro-4,7-epoxy-1H-isoindole-1,3(2H)-dione [32463-
66-4] (10)


To a 250 mL three-necked round-bottomed flask fitted with a me-

chanical stirrer and reflux condenser was added 47.7 g (0.263 mol)

of 9 and 135 mL of acetic anhydride. The stirred mixture was

heated to 89-900C via an oil bath and maintained at this temperature

for 3 h. The resulting solution was cooled to room temperature and

placed in a refrigerator overnight. The precipitate was filtered

and washed with cold benzene. A second crop of crystals was obtained

by concentration of the combined mother liquors in vacuo, followed by

precipitation into water. The combined products were recrystallized

from benzene and dried in vacuo to afford 34.14 g of white crystals.

An additional 10.17 g fraction was obtained from concentration of the

benzene mother liquor (75.4%), mp 139-143C (dec) [literature mp 137-

1380C (dec)].15









H NMR (CDC13, TMS): 2.30 (s, 3H), 2.87 (s, 2H), 5.27 (s, 2H), 6.47
(s, 2H).
C NMR (DMSO-d6, 39.5): 17.08, 44.03, 79.85, 136.02, 165.46, 169.26.

IR (KBr): 3095 (w), 3020 (w, sh), 2998 (m), 1810 (s), 1783 (s), 1735

(s), 1430 (w), 1375 (s), 1350 (m), 1284 (m), 1272 (m), 1230 (s),
1218 (s, sh), 1192 (s), 1168 (s), 1139 (s), 1092 (s), 1060 (s),
1012 (m), 992 (m), 985 (m), 915 (m), 878 (s), 845 (m, sh), 836

(m), 817 (m), 800 (s), 739 (m), 710 (m), 693 (m), 637 (m), 629 (m).
N-Acetoxymaleimide/l-(Acetyloxy)-1H-pyrrole-2,5-dione (11)

To a 100 mL one-necked round-bottomed flask was added 49.47 g of
10 and a Telfon-coated stir bar. A short path vacuum distillation

head was fitted to the flask, and the pressure of the system was re-
duced to 25 mm. The flask was heated slowly to approximately 180'C.
Decomposition of the solid occurred before 140C and was accompanied

by the evolution of furan. The product was then distilled, bp 140-
146C (24 mm Hg), and collected by cooling the receiving flask. Two
recrystallizations from CC14 gave 28.36 g (82.5%) of white crystal-
line product (11), mp 70.5-71.5C (literature mp 70.5-71.5C).15
1H NMR (CDC13, TMS): 2.32 (s, 3H), 6.70 (s, 2H).

(DMSO-d6, TMS): 2.38 (s, 3H), 7.18 (s, 2H).
C NMR (CDC13, TMS): 17.33, 132.44, 164.22, 166.80.

(DMSO-d6, 39.5): 17.03, 133.08, 165.05, 167.49.
IR (KBr): 3080 (w), 3057 (m), 3048 (m), 3003 (w), 2950 (w), 2880 (w),
1818 (s), 1782 (s), 1740 (vs), 1577 (w), 1432 (w), 1380 (s),
1341 (w), 1317 (w), 1177 (s), 1123 (s), 1048 (s), 1007 (w), 820

(s), 778 (m), 670 (s).








Elemental Analysis: Calcd. for C6H5N03: C, 46.46; H, 3.25; N, 9.03.

Found: C, 46.49; H, 3.28, N, 9.04.

Phenyl N-(3,6-Epoxy-1,2,3,6-tetrahydrophthalimidyl) Carbonate/3a,4,
7,7a-Tetrahydro-2-[(phenoxycarbonyl)oxy]-4,7-epoxy-iH-isoindole-
1,3(2H)-dione [60361-88-8] (12)


The following procedure was adopted from Akiyama et al.17 To a

500 mL three-necked round-bottomed flask fitted with a mechanical

stirrer and addition funnel was added 76.4 g (0.422 mol) of 9 and 210

mL of freshly distilled DMF. The flask was cooled to 0-50C via an

external ice bath, and 58.8 mL (0.422 mol) of dry triethylamine was

added. The addition funnel was charged with 66.03 g (0.422 mol) of

phenyl chloroformate which was added to the stirred solution over a

1 h period. The ice bath was removed and the mixture allowed to stir

an additional 3 h. Triethylamine hydrochloride was filtered out and

the filtrate precipitated into 2 L of water. Additional product was

obtained by dissolving the filtered Et3N-HCl in 1 L of water. Both

precipitates were suction filtered and dried in vacuo giving 126.3 g

of crude product. Recrystallization from isopropanol afforded 71.4 g

(56.3%) of white needles, mp 137-1390C (literature mp 135-136C).17
1H NMR (CDCI3, TMS): 2.88 (s, 2H), 5.32 (s, 2H), 6.48 (s, 2H), 7.20-

7.45 (m, 5H).
1C NMR (CDCI3, T'4S): 44.25, 80.47, 120.28, 126.96, 129.74, 136.22,

149.97, 150.70, 168.29.

IR (KBr): 3095 (w), 3075 (w), 3060 (m), 3022 (w), 3003 (w), 1817 (s),

1790 (s), 1740 (vs), 1600 (w), 1585 (m), 1485 (m), 1460 (m), 1360

(m), 1310 (m), 1272 (s), 1230 (vs, br), 1148 (s), 1092 (s), 1068








(s), 1019 (m), 1005 (m, sh), 998 (m), 973 (m), 954 (m), 917 (m),
882 (s), 850 (m), 817 (m), 803 (m), 788 (m), 774 (m), 753 (m),

730 (m), 713 (m), 686 (m), 660 (w), 629 (m), 622 (m).

Phenyl N-Maleimidyl Carbonate/l-[(Phenoxycarbonyl)oxy]-1H-pyrrole-2,
5-dione [60361-89-9] (13)

Into a 250 mL Erlenmeyer flask was placed 38.68 g (0.128 mol) of

12, 0.428 g (2.57 mmol) of 4-tert-butylcatechol, 70 mL of bromobenzene,

and a few boiling chips. The mixture was heated on a hot plate at

such a rate as to allow bromobenzene vapors to condense in the neck

of the flask (~160C inside the flask) for 1.5 h. Bromobenzene was

then removed in vacuo and the resulting solid recrystallized from cy-

clohexane and dried in vacuo giving 24.51 g (81.8%) of maleimide (13)
as a pale-yellow solid, mp 99-102.50C (literature mp 98-990C).17 A

quantity of 13 was sublimed at 1 mm (1000C) affording white crystals,

mp 101-104C.
1H NMR (CDC13, TMS): 6.77 (s, 2H), 7.20-7.45 (m, 5H).

1C NMR (CDC13, TMS): 120.33, 127.06, 129.84, 132.62, 150.75, 163.47.

IR (KBr): 3160 (w), 3100 (m), 3070 (w), 1818 (s), 1783 (s), 1740 (vs),

1587 (m), 1578 (m), 1492 (m), 1482 (m), 1456 (w), 1375 (m), 1220

(vs), 1162 (m), 1155 (m), 1126 (s), 1050 (m), 1023 (m), 1004 (m),
974 (m), 910 (w), 860 (w), 815 (s), 778 (w), 765 (m), 752 (m),

743 (n), 715 (m), 685 (m), 667 (s), 638 (m).

N-Hydroxymaleimide/1-Hydroxy-1H-pyrrole-2,5-dione [4814-74-8] (14)

N-Hydroxymaleimide was prepared via the procedure of Akiyama et

al.17 Thus, to a 100 mL three-necked round-bottomed flask fitted

with a reflux condenser and magnetic stir bar was added 7.358 g









(0.0316 mol) of 13 and 40 mL of freshly distilled methanol. The solu-

tion was refluxed for 2 h, after which the methanol was removed in

vacuo. The residual oil was triturated with a solution of 7:5 hexanes:

benzene, and the resulting solid was recrystallized from toluene and

dried in vacuo to give 1.55 g (43.4%) of an off-white crystalline

solid (14), mp 126-1300C (literature mp 125-126C).17 Spectral prop-

erties were in agreement with those of an authentic sample kindly sup-

plied by Dr. M. Akiyama.

1H NMR (acetone-d6, TMS): 6.76 (s, 2H), 9.20 (br, 1H).

(DMSO-d6, TMS): 6.92 (s, 2H), 10.29 (br, 1H).

C NMR (acetone-d6, TMS): 125.50, 160.05.

(DMSO-d6, 39.5): 131.91, 167.00.

IR (KBr): 3150 (m, br), 3100 (m), 2950 (w), 2850 (w), 1785 (m), 1730

(vs), 1572 (w), 1488 (m), 1306 (w), 1230 (w), 1175 (s), 1130 (m),

1047 (m), 1041 (m), 822 (s), 773 (w), 735 (m), 670 (s).

N-(4-Carbethoxyphenyl)maleanilic Acid/(Z)-4-[(3-Carboxy-1-oxo-2-pro-
penyl)amino]benzoic acid, 1-ethyl ester [53616-17-4] (15)

To a 500 mL Erlenmeyer flask was added 24.4 g (0.148 mol) of

ethyl p-aminobenzoate and 250 mL of chloroform. The stirred solution

was cooled in an ice bath, and 14.5 g (0.148 mol) of maleic anhydride

was added portionwise. After 1 h, the mixture was warmed to room temp-

erature and stirred overnight. The white precipitate was filtered,

washed with CHCl3, and dried in vacuo, affording 38.1 g (98%) of male-

anilic acid (15). A portion of the product was recrystallized from

CH3CN, mp 190-1920C.








1H NMR (DMSO-d6, 2.49): 1.28 (t, 3H), 4.25 (q, 2H), 6.41 (AB q, 2H),

7.84 (AB q, 4H), 10.62 (s, 1H).
C NMR (DMSO-d6, 39.5): 14.20, 60.51, 118.89, 124.74, 130.30, 131.71,

143.07, 163.78, 165.34, 166.95.

IR (KBr): 3300 (m), 3205 (m), 3110 (m), 2975 (w), 1710 (s), 1635 (m),

1610 (m), 1580 (s), 1540 (s), 1470 (m), 1415 (w), 1405 (m), 1365

(m), 1330 (m), 1310 (m), 1270 (s), 1225 (w), 1175 (m), 1120 (m),
1105 (m), 1025 (m), 1010 (w), 970 (m), 900 (w), 865 (m), 850 (m),

770 (m), 695 (w), 680 (w), 610 (m).
N-(4-Carbethoxyphenyl)maleimide/[4-(2,5-Dihydro-2,5-dioxo-1H-pyrrol-
1-yl)benzoic acid, ethyl ester] [14794-06-1] (16)

To a 500 mL one-necked round-bottomed flask was added 38.1 g

(0.145 mol) of 15, 1.2 g (0.015 mol) of anhydrous sodium acetate, and

100 mL of acetic anhydride. A magnetic stir bar was added, and a re-

flux condenser was fitted. The stirring mixture was brought to 900C

over a 1.0 h period, and then allowed to cool to room temperature.

The resulting solution was precipitated into 1.5 L of ice-water and

allowed to stir overnight. The yellow solid was collected by filtra-

tion, recrystallized from ethanol-water, and dried in vacuo, giving

29.57 g (83.4%) of yellow plates, mp 112-1130C (literature mp 1130C).18
H NMR (CDCl3, TMS): 1.38 (t, 3H), 4.37 (q, 2H), 6.84 (s, 2H), 7.80

(AB q, 4H).
13C NMR (CDC13, 77.0): 13.94, 60.77, 124.86, 129.00, 129.93, 133.97,

135.10, 165.26, 168.63.
IR (KBr): 3470 (w), 3090 (w), 2995 (w), 2900 (w), 1718 (vs), 1710

(vs), 1603 (m), 1507 (m), 1472 (w), 1442 (w), 1405 (m, sh), 1395








(s), 1382 (s), 1365 (m, sh), 1307 (m, sh), 1282 (s), 1213 (w),
1175 (m), 1142 (m), 1128 (m), 1108 (m), 1068 (w), 1022 (m),
948 (w), 853 (m), 830 (m), 764 (m), 699 (m), 684 (m), 638 (w).
N-Hydroxymaleamic Acid [4296-73-5] (17)
N-Hydroxymaleamic acid (17) was prepared from the addition of
hydroxylamine [from 61.5 g (0.885 mol) of hydroxylamine hydrochloride
neutralized with one equivalent of sodium methoxide in methanol] to
a solution of 86.8 g (0.885 mol) of maleic anhydride in distilled
dioxane at 00C. After warming to room temperature and stirring for
1 h, the product was filtered and dried in vacuo, affording 69.3 g
(60%) of 17, mp 126-1290C (dec) [literature mp 122-128C (dec)].19
1H NMR (DMSO-d6, TMS): 6.30 (s, 2H).
1C NMR (DMSO-d6; 39.5): 129.22, 132.98, 162.17, 165.93.

IR (KBr): 3500-2600 (br, s), 3180 (s), 1695 (m), 1630 (s), 1540 (br,
vs), 1400 (s), 1310 (m), 1230 (br, s), 1080 (m), 1065 (s), 990

(m), 980 (m), 915 (m), 847 (m), 800 (m), 730 (m), 630 (m).
N-Carbethoxymaleimide/2,5-Dihydro-2,5-dioxo-1H-pyrrole-l-carboxylic
acid, ethyl ester [55750-49-7] (18)

This maleimide was prepared by the method of Keller and Rudinger2
in 44% yield, mp 55-570C (literature mp 58-59C).20
1H NMR (CDC13, TMS): 1.42 (t, 3H), 4.45 (q, 2H), 6.84 (s, 2H).

IR (KBr): 3180 (w), 3100 (m), 2985 (m), 1795 (s), 1770 (vs), 1710 (m),
1595 (m), 1475 (m), 1445 (m), 1398 (m), 1370 (m), 1330 (s), 1265
(s), 1130 (m), 1102 (m), 1053 (m), 1035 (m), 995 (m), 850 (m),
765 (m), 755 (m), 690 (m), 635 (m).








N-[2-(4-Imidazolyl)ethyl]maleamic Acid/(Z)-4-([2-(1H-Imidazol-4-yl)
ethyl]amino)-4-oxo-2-butenoic Acid (19)

In an Erlenmeyer flask was combined 0.437 g (3.93 mmol) of hista-

mine (20), 0.367 g (3.74 mmol) of maleic anhydride and 20 mL of chloro-
form (ethanol-free). The mixture was stirred for 20 h; the solid fil-

tered and dried in vacuo, affording 0.672 g (86%) of 19, which slowly
decomposed above 1200C.
1H NMR (D20, DSS): 2.95 (m, 2H), 3.52 (m, 2H), 6.13 (AB q, 2H), 7.26

(s, 1H), 8.53 (s, 1H).
IR (KBr): 3600-2400 (br, m), 3230 (w), 3135 (w), 3060 (w), 1655 (m),

1625 (s), 1570 (br, s), 1450 (w), 1430 (w), 1398 (w), 1365 (w),
1313 (w), 1270 (m), 1208 (w), 1185 (m), 1100 (br, m), 1065 (w),
975 (m), 902 (w), 855 (br, m), 815 (m), 730 (w), 715 (m), 638

(m), 610 (m).
N-(2-Thiazolyl)maleamic Acid/(Z)-4-Oxo-4-(2-thiazolylamino)-2-bute-
noic Acid [19789-91-4] (21)

Into an Erlenmeyer flask was placed 0.922 g (9.21 mmol) of 2-
aminothiazole (recrystallized from cyclohexane), 0.902 g (9.20 mmol)

of maleic anhydride and 40 mL of acetone. The mixture was stirred
for 45 h at room temperature. The solid was filtered, washed with

acetone and dried in vacuo, affording 1.308 g (72%) of yellow powder

(21), mp 151-1530C (dec).
H NMR (DMSO-d6, 2.49): 6.46 (s, 2H), 7.37 (AB q, 2H).
1C NMR (DMSO-d6, 39.5): 113.97, 128.20, 132.54, 137.90, 157.64,

162.56, 167.14.








IR (KBr): 3090 (w), 3000-2200 (br, m), 1655 (m), 1618 (m), 1565 (br,
s), 1435 (m), 1398 (m), 1322 (m), 1270 (s), 1205 (m), 1172 (m),
1060 (m), 905 (m), 850 (m), 775 (m), 725 (m), 705 (m), 650 (m),
620 (m).
N-(4-Carboxyphenyl)maleanilic Acid/4-[(3-Carboxy-l-oxo-2-propenyl)
amino]benzoic Acid [36847-92-4] (22)

This compound was previously synthesized in these laboratories21
from p-aminobenzoic acid and maleic anhydride, mp 2340C (dec).
H NMR (DMSO-d6, TMS): 6.19 (AB q, 2H), 7.72 (AB q, 4H),10.48 (br, 1H)

IR (KBr): 3350-2010 (br, m), 3310 (m), 3210 (w), 3000 (w), 2840 (br,
w), 2665 (w), 2540 (w), 2240 (w), 1705 (s), 1690 (s), 1625 (m),
1580 (s), 1540 (vs), 1420 (m), 1405 (m), 1325 (m), 1310 (m),
1290 (s), 1265 (m), 1220 (w), 1175 (m), 1120 (w), 1012 (w), 970
(m), 940 (w), 900 (w), 860 (m), 845 (m), 770 (m), 690 (m), 670
(m), 608 (m).
4-[(3-Carboxy-l-oxo-2-propenyl)amino]benzeneacetic Acid (23)
This compound was previously synthesized in these laboratories21
from p-aminophenylacetic acid and maleic anhydride, and was used with-
out further purification.
H NMR (DMSO-d6, TMS): 3.57 (s, 2H), 6.41 (AB q, 2H), 7.41 (AB q,
4H), 10.43 (br, 1H).
IR (KBr): 3280 (s), 3190 (w), 3050 (m), 2720 (w), 2620 (w), 2390 (w),
2240 (w), 1715 (s), 1685 (s), 1615 (s), 1570 (s), 1535 (vs),
1510 (s), 1425 (m), 1400 (m), 1320 (m), 1300 (m), 1265 (m), 1220
(m), 1200 (w), 1180 (m), 1050 (m), 980 (m), 925 (m), 900 (m),
860 (m), 840 (m), 812 (m), 790 (m), 775 (m), 720 (m), 670 (w),
630 (m), 610 (m).








N-[2-(4-Imidazolyl)ethyl]-3,6-endoxo-l,2,3,6-tetrahydrophthalic Acid
(24)

To a 50 mL Erlenmeyer flask was added 2.505 g (0.0136 mol) of

histamine dihydrochloride and 15 mL of water. To the stirred solu-

tion was carefully added 2.286 g (0.0272 mol) of NaHCO3.

Into another flask was placed 2.263 g (0.0136 mol) of 8 and 22

mL of acetone. The solution of free-base (20) in water was slowly

added to the acetone solution with rapid stirring. Addition of addi-

tional acetone (200 mL) was necessary to make the flask contents homo-

geneous. After stirring 1 h, the liquid phase was decanted off, and

the remaining oily precipitate stirred over fresh acetone. The re-

sulting fine white solid was collected and dried in vacuo to give

4.898 g of 24, apparently contaminated by NaC1. The solid gradually

decomposed upon heating to 1350C.

H NMR (D20, DSS): 2.73 (s, 2H), 2.67-3.63 (m, 4H), 5.07 (d, 2H),

6.43 (m, 2H), 7.12 (m, 1H), 8.48 (d, 1H).

IR (KBr): 3660-2730 (m, br), 3240 (m), 3120 (m), 1715 (w), 1650 (s),

1625 (s), 1555 (s), 1430 (m), 1395 (s), 1310 (w), 1270 (m), 1245

(w), 1218 (m), 1183 (w), 1167 (w), 1092 (w), 1060 (w), 1028 (w),

1000 (w), 982 (w), 972 (w), 930 (w), 900 (m), 838 (m), 820 (m),

808 (w), 752 (w), 730 (m), 702 (m), 627 (m),

Succinimides and Succinamic Acids

N-[2-(4-Imidazolyl)ethyl]succinamic Acid/4-([2-(1H-Imidazol-4-yl)
ethyl]amino)-4-oxo-2-butanoic Acid (25)

To an Erlenmeyer flask containing a solution of 0.248 g (2.48

mmol) of succinic anhydride in 5 mL of acetone was added dropwise a








solution of 0.275 g (2.47 mmol) of histamine in 3.5 mL of water, and

the solution was stirred overnight. Absolute ethanol and acetone

were added, and the precipitate was collected and dried in vacuo,

giving 0.239 g (45.8%) of white solid, mp 159-159.50C.
H NMR (DMSO-d6, 2.49): 2.37 (m, 4H), 2.63 (m, 2H), 3.26 (m, 2H),

6.84 (s, 1H), 7.68 (s, 1H), 7.98 (t, 1H).
1C NMR (DMSO-d6, 39.5): 26.68, 29.75, 30.44, 38.87, 117.19, 134.00,

134.73, 171.34, 174.41.

IR (KBr): 3240 (w), 3155 (m), 3100 (m), 3000 (m), 2940 (m), 2855 (m),

1635 (vs), 1610 (s), 1570 (s), 1450 (w), 1420 (s), 1352 (s),

1285 (w), 1205 (s), 1140 (m), 1110 (m), 1065 (w), 1035 (w), 975

(w), 940 (w), 905 (w), 865 (m), 820 (m, br), 770 (m), 720 (m),

640 (m).

N-[2-(4-Imidazolyl)ethyl]succinimide/1-[2-(lH-Imidazol-4-yl)ethyl]-
2,5-pyrrolidinedione (26)

A 25 mL three-necked round-bottomed flask fitted with a stir bar,

condenser, and gas inlet tube was assembled hot and was cooled by flush-

ing the apparatus with Ar. To the cool flask was introduced 0.734 g

(7.34 mmol) of succinic anhydride and 2 mL of distilled DMF. To the

stirred solution was added via syringe a solution of 0.820 g (7.38

mmol) of histamine (20) in 3 mL of DMF. A white solid formed which
dissolved when the mixture was heated. The solution was refluxed for

2.5 h and allowed to cool. DMF was removed in vacuo, leaving a brown

solid which was recrystallized from CHCl3, mp 164-165C.

H NMR (DMSO-d6, 2.49): 2.58 (s, 4H), 2.67 (m, 2H), 3.56 (m, 2H),

6.83 (s, 1H), 7.57 (s, 1H), 8.87 (br, 1H).








C NMR (DMSO-d6, 39.5): 24.83, 28.00, 38.04, 116.36, 133.86, 134.88,

177.57.
IR (KBr): 3440 (w), 3120 (w), 3080 (w), 3035 (w), 2990 (w), 2940 (2),

2830 (m), 2750 (w), 2640 (m), 1765 (m), 1690 (vs), 1575 (m),

1485 (m), 1450 (m), 1438 (m), 1433 (m), 1405 (s), 1330 (s), 1318

(m), 1289 (m), 1260 (w), 1248 (s), 1230 (m), 1150 (s), 1090 (m),
1055 (m), 1030 (w), 1000 (sh, m), 990 (m), 950 (m), 910 (br, m),

840 (m), 825 (m), 798 (m), 772 (m), 660 (m), 630 (m), 608 (w).
N-Acetoxysuccinimide [14464-29-0] (27)

To a dry 250 mL three-necked round-bottomed flask fitted with a
mechanical stirrer, N2 inlet tube and septum cap was added 3.0 g

(0.026 mol) of N-hydroxysuccinimide, 100 mL of anhydrous ether, and

20 mL of distilled THF. Dry pyridine (2.06 g, 0.026 mol) was added

under N2, and the flask was cooled to 0-50C. To the stirred solution

was added dropwise via syringe 1.5 mL (0.0265 mol) of acetyl chloride.

The mixture was stirred for 0.5 h at 00 and then at room temperature

for 1 h. The flask contents were transferred to a separatory funnel

and extracted with 1 N HC1. The organic layer was dried over anhy-

drous MgSO4, the solvent removed in vacuo, and the residue triturated

with hexanes to give white solid. The solid was recrystallized from
benzene-hexanes, filtered, and dried in vacuo to afford 1.496 g (36%)

of needles (27), mp 131-133.5C (literature mp 132-133C).22
1H NMR (CDC13, TMS): 2.33 (s, 3H), 2.82 (s, 2H).

C NMR (CDC13, TMS): 17.50, 25.59, 165.71, 169.41.

IR (KBr): 2990 (w), 2940 (w), 1822 (s), 1795 (s), 1745 (vs), 1430

(m), 1380 (s), 1360 (sh, m), 1298 (w), 1255 (m), 1220 (s), 1170









(s), 1160 (sh, s), 1075 (sh, m), 1060 (s), 1045 (m), 1005 (w),

990 (w), 832 (s), 810 (m), 765 (m), 650 (m).

Vinyl Ethers
N-(B-Vinyloxyethyl)imidazole/l-[2-(Ethenyloxy)ethyl] -1H-imidazole (28)

The general procedure for N-alkylation of imidazole described by

Fournari et al.23 was used. To a nitrogen-flushed 500 mL three-necked

round-bottomed flask fitted with a mechanical stirrer, condenser, and

addition funnel was added 100 mL of freshly distilled THF and 13.2 g

(0.339 mol) of potassium metal. The addition funnel was charged with

a solution of 25.37 g (0.373 mol) of imidazole in 150 mL of THF, which

was added over a 1.5 h period. Refluxing the rapidly stirred mixture

for 2 h consumed all visible potassium. A solution of 40 mL (0.39

mol) of 2-chloroethyl vinyl ether (CEVE) and 20 mL of THF was added

over 1 h, and reflux was maintained an additional 17 h. Precipitated

KC1 was removed by filtration, and the solvent evaporated in vacuo.

The resulting oil was dried over CaH2 and distilled (131.5-134C, 4.0

mm), affording 31.2 g of pale-yellow oil. 1H NMR indicated the pre-

sence of imidazole (-25%). The oil was dissolved in THF and stirred

over NaH overnight. The precipitate was filtered, and the filtrate

concentrated in vacuo and dried over CaH2. Short-path distillation

gave 21.86 g (46.7%) of pure 28, bp 90-92C (0.5 mm),as a colorless

oil. The product was stored over CaH2 at room temperature.

1H NMR (CDC13, TMS): 3.74-4.40 (m, 6H), 6.38 (X of ABX, 1H), 6.98

(m, 2H), 7.47 (s, 1H).

(DMSO-d6, TMS): 3.83-4.47 (m, 4H), 6.46 (X of ABX, 1H), 6.93

(t, 1H), 7.15 (t, 1H), 7.60 (s, 1H).









C NMR (CDC13, 77.0): 44.93, 65.96, 86.48, 118.35, 128.08, 136.36,

149.89.

IR (neat, NaCl): 3115 (m), 2940 (m), 2880 (m), 1620 (br, s), 1506

(s), 1465 (m), 1440 (m), 1365 (s), 1325 (s), 1285 (s), 1230 (s),
1195 (br, s), 1150 (sh, m), 1110 (s), 1092 (sh, s), 1078 (s),

1038 (s), 1028 (sh, m), 990 (m), 963 (sh, s), 952 (s), 915 (m),

906 (s), 820 (br, s), 740 (br, s), 662 (s), 622 (s).

LRMS (m/e, rel. intensity): 138 (M1, 19.2), 137 (11.9), 109 (19.4),

108 (96.4), 95 (14.0), 94 (10.0), 86 (19.7), 84 (32.7), 82

(20.0), 81 (100).
HRMS: m/e 138.07744 (calcd. for C7H10N20 = 138.07931).

Elemental Analysis: Calcd. for C7H10N20: C, 60.85; H, 7.29; N, 20.27.

Found: C, 60.85; H, 7.32; N, 20.28.

N-(B-Vinyloxyethyl)piperidine/1-[2-(Ethenyloxy)ethyll-piperidine
[702-06-71 (29)

This vinyl ether was synthesized via the method of Goette.24
Thus, to a 250 mL three-necked round-bottomed flask fitted with a

magnetic stir bar, condenser, and addition funnel was added 42.5 g

(0.506 mol) of NaHCO3, 25 mL of water and 25 mL (0.253 mol) of piperi-

dine. The addition funnel was charged with 77 mL (0.759 mol) of CEVE

and the contents added over a 1.5 h period to the gently refluxing
mixture. Reflux was maintained for 17 h after addition was complete.
Ether was added to the cool flask, and the organic phase was dried

over NaOH for several days. Ether and excess CEVE were removed under

reduced pressure. The residue was distilled under vacuum, affording








35.2 g (87.0%) of colorless oil (29), bp 75-76.50C (10 mm) [litera-

ture bp 72.3-730C (7.5 mm)].24
H NMR (CDC13, TMS): 1.23-1.88 (m, 4H), 2.22-2.80 (m, 4H), 3.72-4.37

(m, 4H), 6.51 (X of ABX, 1H).
C NMR (CDC13, 77.0): 23.73, 25.34, 54.39, 57.26, 64.82, 85.58,

151.18.

IR (neat, NaCI): 3120 (w), 3080 (w), 3050 (w), 2940 (s), 2855 (m),

2780 (m), 2750 (m), 1635 (m), 1610 (s), 1478 (m), 1455 (m),

1442 (m), 1383 (w), 1352 (m), 1320 (s), 1305 (m), 1280 (m), 1262

(m), 1200 (s), 1160 (m), 1126 (m), 1090 (m), 1080 (m), 1040 (m),
1023 (w), 1000 (m), 984 (m), 962 (m), 945 (w), 862 (m), 810 (s),

780 (w), 760 (w), 700 (w).
B-Vinyloxyethyl(imidazol-4ylmethyl)piperidinium Chloride (30)

The method reported by Tonellato25 was employed. To a 50 mL

one-necked round-bottomed flask containing a stir bar was added 1.338 g

(8.74 mmol) of 4-(chloromethyl)imidazole hydrochloride (31) and 10 mL

of anhydrous methanol. To the stirred solution at room temperature

was added 2.771 g (17.8 mmol) of 29 in one portion, and the solution

was stirred for 0.5 h. Approximately 1 g of Na2CO3 was added, the
mixture stirred for 5 min, and filtered. The filtrate was reduced in

volume on a rotary evaporator and suction filtered again. Slow addi-

tion of the filtrate into ether gave an oily precipitate, which was
taken up in 10 mL of anhydrous methanol, again stirred over ~1 g of

Na2CO3, filtered, and the filtrate reduced in vacuo. The viscous oil

was triturated with acetonitrile, suction filtered and reduced in

volume. Precipitation into ether gave an oily residue. This process









(treatment with Na2CO3, etc.) was repeated 2 additional times to en-

sure complete removal of 29 as its free base. Final drying of the

oily precipitate in vacuo overnight afforded 1.998 g (84%, crude) of

hydroscopic solid (30). Proton NMR revealed the presence of ether

as a major contaminant.

H NMR (D20, DSS): 1.50-2.17 (m, 6H), 3.25-3.69 (m, 6H), 4.17-4.53

(m, 4H), 4.63 (s, 2H), 6.60 (X of ABX, 1H), 7.52 (s, 1H), 7.86

(s, 1H).

1C NMR (D20, DSS): 22.17, 23.15, 58.87, 59.95, 61.80, 63.94, 91.33,

124.57, 129.11, 140.02, 153.18.

IR (KBr): 3600-2500 (br, s), 1625 (s), 1558 (w), 1495 (sh, m), 1465

(m), 1435 (sh, m), 1370 (m), 1325 (m), 1295 (w), 1195 (s), 1090

(m), 1028 (m), 977 (m), 942 (w), 897 (m), 865 (m), 830 (m), 796

(m), 663 (m), 626 (s).

Imidazole and Histamine Derivatives

Histamine/lH-Imidazole-4-ethanamine [51-45-6] (20)

Free base (20) was prepared from histamine dihydrochloride by

three methods.

Method A. The procedure of Tabor and Mosettig26 was used.

A 2% solution of histamine dihydrochloride in 95% ethanol was

slowly trickled through a column of Amberlite IRA-400 ion exchange

resin. The percolate was reduced to an oil on a rotary evaporator,

and distilled under vacuum, bp 134-1350C (0.075 mm) [literature bp

209-210C (18 mm)],27 affording a colorless to pale-yellow viscous

oil. Distilled yields were generally poor and the purity and boiling

point of the product variable.









'H NMR (DMSO-d6, TMS): 2.42-3.00 (m, 4H), 4.97 (br, 3H), 6.77 (s,

1H), 7.54 (s, 1H).

Method B. To a 50 mL Erlenmeyer flask was added 5.638 g (0.03063

mol) of histamine dihydrochloride and -10 mL of H20. To the stirred

solution was added in small increments 5.146 g (0.06125 mol) of NaHCO3,

and the flask was allowed to stand overnight. Solvent was removed in

vacuo, and the resultant colorless oil was triturated with absolute

ethanol. The precipitate was filtered out, and the filtrate reduced

in volume in vacuo. Short-path distillation of the resultant oil

afforded 1.597 g (46.9%) of 20 as a viscous oil, bp 140-143C (1.0 mm).

Spectral properties of this material were identical to those of 20

made by Method A.

Method C. To an Erlenmeyer flask containing 6.728 g (0.0365 mol)

of histamine dihydrochloride dissolved in 10 mL of H20 was added

18.25 mL (0.0730 mol) of 4 N NaOH solution. The solution was stirred

for 0.5 h, and the solvent was removed in vacuo. The resultant thick

oil was triturated with 95% ethanol, filtered, and the filtrate re-

duced to an oil in vacuo. The oil was distilled in a Kugelrohr appa-

ratus (0.050 mm, ~1600C), affording 3.245 g (80%) of a colorless oil,

which crystallized on standing, mp 85-880C (literature mp 83-84C).27

4-(Hydroxymethyl)imidazole Hydrochloride/1H-Imidazole-4-methanol
[32673-41-9] (32)

This material was prepared by the method of Totter and Darby.28

To a 1 L three-necked round-bottomed flask fitted with a mechanical

stirrer and reflux condenser was added 250 mL of benzene, 125 mL of

water and 50 mL (0.6 mol) of 37% HC1. The mixture was brought to 80C








via an oil bath, and 50.0 g (0.153 mol) of 4-(hydroxymethyl)imidazole

picrate was added in one portion. Stirring was continued until all

the solid had dissolved, at which time heating was discontinued and

the flask allowed to cool. The aqueous phase was extracted 5 times

with 150 mL portions of benzene, stirred over ~2 g of Norit-A and con-

centrated in vacuo. Recrystallization from absolute ethanol gave

15.45 g (69.3%) of yellow crystals, mp 105-1090C (literature mp 107-

1090C).28 A second recrystallization from absolute ethanol gave

14.25 g of pale-yellow crystals, mp 107-1100C.
1H NMR (D20, DSS): 5.00 (br, 2H), 7.52 (br, 1H), 8.79 (br, 1H).

1C NMR (020, DSS): 56.00, 119.26, 134.95, 136.37.

IR (KBr): 3500-2500 (br, s), 1615 (s), 1520 (w), 1458 (s), 1450 (sh,

s), 1420 (s), 1362 (m), 1290 (m), 1258 (m), 1252 (m), 1210 (m),

1140 (s), 1070 (s), 1032 (s), 974 (m), 920 (m), 870 (m), 828 (sh,

s), 813 (s), 745 (m), 620 (s).

4-(Chloromethyl)imidazole Hydrochloride/4-(Chloromethyl)-1H-imidazole
Hydrochloride [31036-72-3] (31)

The procedure of Turner et al.29 was employed. To a 100 mL three-

necked round-bottomed flask equipped with a mechanical stirrer, con-

denser, drying tube, and addition funnel was added 14.25 g (0.106

mol) of 32 and 10 mL of benzene. The addition funnel was charged with

11 mL (0.15 mol) of thionyl chloride and 20 mL of benzene, .nd the

solution was added to the rapidly stirred suspension over a 1 h period.

The mixture was refluxed for 2 h, and then allowed to stand at room

temperature overnight. The solid product was suction filtered, washed

with benzene and dried in vacuo. Recrystallization from acetonitrile-









absolute ethanol afforded 11.50 g (71.0%) of off-white crystals, mp

141-144C (literature mp 144C).30
13C NMR (ethanol-d1, 17.2): 33.23, 117.94, 130.03, 134.56.

IR (KBr): 3500-2500 (s, br), 3140 (m), 1615 (m), 1460 (m), 1430 (m),

1290 (m), 1265 (w), 1168 (w), 1147 (m), 1076 (w), 1062 (m), 978

(m), 922 (m), 900 (m), 853 (m), 808 (m), 765 (w), 720 (m), 675

(w), 620 (s).
Dichlorobis(l-[2-(ethenyloxy)ethyl]-1H-imidazole-N3)zinc (33)

The method of Eilbeck et al.31 was employed. In a 25 mL Erlen-
meyer flask was weighed 0.198 g (1.45 mmol) of ZnCl, and 4 mL of ab-

solute ethanol was added. To the stirred solution was added 0.803 g

(5.81 mmol) of 28, the transfer aided by 2 mL of ethanol. The solu-

tion was stirred for 1 h, at which time anhydrous ether was added

dropwise until the solution became turbid. On standing, a colorless

oil precipitated from solution. Enough absolute ethanol was added to

redissolve the precipitate, and the flask was allowed to stand for 12
days. Upon addition of ether, a white crystalline mass precipitated

from solution. The solid was collected, washed with ether, and dried

in vacuo, affording 0.535 g (89%) of 33, mp 78.5-800C.

IR (KBr): 3115 (m), 3040 (w), 2925 (w), 2875 (w), 1635 (sh, m), 1620

(s), 1525 (m), 1442 (w), 1397 (w), 1365 (w), 1322 (m), 1240 (m),
1232 (m), 1187 (s), 1112 (m), 1097 (s), 1033 (m), 992 (m), 952

(m), 850 (m), 830 (m), 760 (m), 668 (m), 653 (m), 630 (m).
Elemental Analysis: Calcd. for C14H20N402.ZnC12: C, 40.75; H, 4.89;

N, 13.58; C1, 17.18. Found: C, 40.72; H. 4.91; N, 13.51; C1,
17.09.








Dichlorobis(1-methyl-1H-imidazole-N3)zinc-(T-4) [23570-24-3] (34)

N-methylimidazole-ZnCl2 complex was prepared in an analogous man-

ner to 33. Thus, the reaction of 0.294 g (2.16 mmol) of ZnC12 and

1.088 g (13.25 mmol) of N-methylimidazole in 15 mL of 95% ethanol gave,

after precipitation with ether, 0.512 g (79%) of fine-white solid (34),

mp 205-208C (literature mp 2090C).32

IR (KBr): 3150 (w), 3125 (s), 1695 (w), 1635 (w), 1588 (w), 1535 (m),

1520 (m), 1425 (m), 1287 (m), 1235 (s), 1105 (s), 1092 (s), 1025

(w), 955 (m), 847 (m), 775 (m), 740 (m), 668 (m), 653 (s), 620

(m), 615 (m).

Elemental Analysis: Calcd. for C8H12N4'ZnC12: C, 31.98; H, 4.02; N,

18.64; Cl, 23.60. Found: C, 32.03; H, 4.07; N, 18.59; Cl, 23.59.

N-[(Ethenyloxy)carbonyl)]-1H-imidazole-4-ethanamine (35) and 7,8-Dihy-
dro-5-oxo-imidazo[l,5-c]pyrimidine (36)

To a 100 mL three-necked round-bottomed flask containing a stir

bar and an addition funnel was added 5.522 g (0.030 mol) of histamine

dihydrochloride, 10 mL of water, and 13 mL of dioxane. To the stirred

mixture was added in portions 7.562 g (0.090 mol) of NaHCO3. The

flask was cooled to 00, and a solution of 3.19 g (0.030 mol) of vinyl

chloroformate in 12 mL of dioxane was added over 25 min. The mixture

was stirred an additional 0.5 h and then warmed to room temperature.

NaCI was filtered, and the filtrate was reduced in volume in vacuo.

The resulting oil was chromatographed on a basic alumina column (3:2

CHC13:methanol eluting solvent). One large fraction was collected;

removal of solvent in vacuo gave 2.361 g of yellow oil. 1H NMR indi-

cated the desired mono acylated product (35) was present. The oil was









rechromatographed on a silica gel column (4% methanol:CHCl3 eluting

solvent). Two products were isolated, 35, 0.108 g (2%), mp 88-890C

and 36, 0.260 g (6.3%), mp 219-221C (dec).

35
H NMR (CDC13, TMS): 2.83 (t, 2H), 3.51 (m, 2H), 4.37-4.79 (AB of

ABX, 2H), 5.67 (br, 1H), 6.83 (d, 1H), 7.16 (X of ABX, 1H), 7.57

(d, 1H), 9.19 (br, 1H).
1C NMR (acetone-d6, 29.8): 28.05, 41.69, 94.13, 116.46, 135.71,

136.87, 143.15, 154.18.

(CDC13, TMS): 27.49, 41.04, 95.28, 115.90, 135.00, 136.12,

142.22, 153.91.

IR (KBr): 3220 (m), 3005 (w), 2965 (w), 2940 (w), 1708 (s), 1647 (m),

1570 (m), 1550 (m), 1485 (w), 1450 (m), 1425 (w), 1362 (w), 1310

(m), 1295 (m), 1277 (m), 1260 (m), 1222 (m), 1190 (w), 1158 (m),

1082 (m), 1040 (m), 983 (m), 974 (m), 952 (m), 860 (m), 820 (m),
785 (m), 764 (w), 735 (w), 700 (w), 617 (m).

LRMS (m/e, rel. intensity): 181 (M+, 0.1), 138 (5.9), 137 (30.6),

82 (10.2), 81 (100).

HRMS: m/e 181.0828 (calcd. for C8H11N302 = 181.0851).

Elemental Analysis: Calcd. for CsH11N302: C, 53.03; H, 6.12; N,

23.19. Found: C, 53.09; H, 6.14; N, 23.20.

36
1 NMR (DMSO-d6, 2.49): 2.84 (t, 2H), 3.26-3.42 (m, 2H), 6.77 (d,

1H), 8.04 (d, 1H), 8.17 (br, 1H).
1C NMR (DMSO-d6, 39.5): 19.27, 38.72, 124.64, 127.33, 134.00, 148.38.









IR (KBr): 3220 (br, m), 3115 (s), 2960 (w), 2940 (w), 2920 (w), 2890

(m), 1735 (sh, s), 1710 (s), 1580 (w), 1473 (m), 1455 (m), 1430

(m), 1410 (s), 1360 (w), 1342 (m), 1327 (m), 1310 (w), 1297 (w),
1258 (w), 1232 (w), 1210 (s), 1180 (m), 1150 (m), 1080 (m), 1060

(m), 1045 (m), 930 (m), 865 (w), 833 (m), 755 (m), 680 (m),650 (m).
LRMS (m/e, rel. intensity): 138 (2.5), 137 (M+, 26.5), 81 (100).

HRMS: m/e 137.05836 (calcd. for C6H7N30 = 137.05891).

Elemental Analysis: Calcd. for C6H7N30: C, 52.55; H, 5.14; N, 30.64.

Found: C, 52.51; H, 5.17; N, 30.65.

N,1-[(Diethenyloxy)carbonyl]-1H-imidazole-4-ethanamine (37)

To a 200 mL three-necked round-bottomed flask equipped with an

addition funnel was added 0.97 g (8.7 mmol) of 20 and 50 mL of ethanol-

free CHCl3. The solution was cooled to 00C, and 1.2 mL (8.6 mmol) of

dry triethylamine was added. The addition funnel was charged with

0.88 g (8.3 mmol) of vinyl chloroformate and 50 mL of CHC13, and the

contents were added over a 2.5 h period. The flask was allowed to

reach room temperature, and water was added. The organic phase was

twice extracted with 50 mL portions of water and dried over anhydrous

MgSO4. Removal of solvent in vacuo gave a white solid which was re-

crystallized from cyclohexane, filtered, and dried in vacuo, afford-

ing 0.40 g (38% based on vinyl chloroformate) of 37, mp 99-1000C.

H NMR (CDCI3, TMS): 2.79 (t, 2H), 3.55 (m, 2H), 4.36-5.24 (2 AB of

2 ABX, 4H), 5.40 (br, 1H), 7.09-7.39 (2 X of 2 ABX, 2H), 7.26

(d, 1H), 8.13 (d, 1H).
C NMR (CDCI3, 77.0): 27.73, 39.96, 94.79, 100.35, 113.65, 136.95,

140.85, 141.67, 141.97, 145.77, 153.42.









IR (KBr): 3240 (m), 3145 (w), 3050 (m), 2940 (w), 1775 (s), 1735 (s),

1640 (m), 1587 (m), 1560 (m), 1488 (m), 1453 (w), 1440 (w), 1406

(s), 1370 (m), 1327 (m), 1295 (m), 1265 (s), 1247 (s), 1215 (m),
1197 (m), 1173 (m), 1138 (m), 1108 (m), 1055 (m), 1010 (m), 982

(m), 965 (w), 952 (m), 943 (m), 880 (m), 847 (m), 838 (m), 752

(m), 730 (m), 680 (w), 668 (w).
LRMS (m/e, rel. intensity): 253 (0.3), 252 (0.7), 251 (M+, 0.8), 210

(2.0), 209 (5.2), 208 (40.0), 207 (8.7), 164 (21.3), 152 (26.9),
151 (38.9), 138 (34.0), 137 (13.0), 95 (24.7), 81 (100).
HRMS: m/e 251.0899 (calcd. for C11H13N304 = 251.0906).

Elemental Analysis: Calcd. for C11H13N304: C, 52.59; H, 5.22; N,

16.73. Found: C, 52.58; H, 5.31; N, 17.21.

4-Allylimidazole/4-(2-Propenyl)-1H-imidazole [50995-98-7] (38)

A 250 mL three-necked round-bottomed flask, mechanical stirring
rod, condenser, and addition funnel were assembled while hot and

cooled by flushing with N2. To the flask was added 3.408 g (0.140

mol) of Mg turnings; the addition funnel was charged with 100 mL of

freshly distilled THF and 10 mL (0.142 mol) of vinyl bromide. Reac-

tion was initiated by addition of a solution of a drop of ethylene
bromide in 10 mL of THF. The vinyl bromide solution was then added

at a rate which maintained a gentle reflux. When formation of Grignard
reagent was complete, the solution was cooled to 0OC via an external
ice bath. To the flask was added 4.289 g (0.0280 mol) of 31 in -15

equal portions over a 2.5 h period. The rapidly stirred mixture was
maintained at 00C for an additional 0.5 h, then allowed to warm to

room temperature and was quenched by careful addition of 20 mL of









saturated NH4Br. Additional water was added to dissolve the pre-
cipitated salts, and the organic layer was separated. The aqueous

layer was extracted with 2-150 mL portions of CHC13, and the combined
organic fractions were dried over anhydrous MgSO4. Solvent was re-

moved in vacuo, giving dark-yellow oil. This oil was chromatographed

on a column of silica gel using a mixture of CHC13:CH30H (95:5) as
eluting solvent. Fractions were combined which gave an Rf 0.30 by
TLC [silica gel, CHC13:CH30H (95.5)]. Removal of solvent in vacuo

afforded 1.372 g (45%) of pale-yellow oil (38) having identical 1H
NMR properties as reported by Begg et al.
1H NMR (CDC13, TMS): 3.30-3.45 (m, 2H), 5.00-5.20 (m, 2H), 5.79-6.20

(m, 1H), 6.81 (d, 1H), 7.60 (d, 1H), 11.05 (br, 1H).
C NMR (CDCI3, TMS): 31.39, 116.14, 117.31, 134.76, 135.25, 135.78.

IR (neat, NaC1): 3500-2300 (br, s), 3080 (m), 3015 (w), 2985 (m),

2850 (br, m), 2740 (w), 2640 (w), 1640 (m), 1588 (m), 1570 (m),
1473 (br, m), 1430 (m), 1323 (w), 1298 (m), 1262 (m), 1230 (m),
1195 (w), 1160 (w), 1105 (m), 1088 (m), 990 (s), 940 (m), 915

(s), 820 (m), 750 (m), 662 (m), 625 (m).
LRMS (m/e, rel. intensity): 109 (6.6), 108 (M+, 68.4), 107 (100),
82 (20.7), 81 (85.5), 80 (86.2), 54 (26.8), 53 (40.9).
HRMS: m/e 108.06875 (calcd. for C6HgN2 = 108.06875).
4-Nitroimidazole/4-Nitro-1H-imidazole [3034-38-6] (39)
This material was prepared in accordance with the method of
Stambaugh and Manthei34 in 31% yield, mp 308-3090C (literature mp
308-310C).34
1H NMR (DMSO-d6, 2.49): 7.83 (d, 1H), 8.29 (d, 1H).









Other Monomers
2-Propenylphenol/(E) and (Z)-2-(1-Propenyl)-phenol [6380-21-8] (40)

This monomer was synthesized via the isomerization of 2-allyl-
phenol as reported by Tarbell.35 The product consisted of both E and

Z isomers (87%), bp 115-1230C (17 mm), [literature bp 110-115C (15-

16 mm)].35
H NMR (CDC13, TMS): 1.69 and 1.86 (2 d of d, 3H), 5.34 (br, 1H),

5.85-7.34 (m, 6H).
1C NMR (CDC13, 77.0): 14.42, 18.71, 115.11, 115.70, 120.33, 120.86,

123.93, 125.25, 127.20, 127.83, 127.98, 128.47, 129.73, 130.86,

152.15.

IR (neat, NaCl): 3540-3300 (br, s), 3060 (m), 3035 (m), 2960 (m),

2935 (m), 2910 (m), 2875 (w), 1850 (m), 1730 (w), 1655 (w), 1605

(m), 1580 (m), 1495 (s), 1483 (s), 1450 (s), 1330 (br, m), 1282

(m), 1225 (br, s), 1172 (s), 1150 (m), 1105 (m), 1080 (m), 1037

(m), 965 (s), 945 (sh, m), 840 (m), 790 (m), 750 (s), 717 (m),
610 (m).
Isoeugenol/2-Methoxy-4-(1-propenyl)-phenol [97-54-1] (41)

Isoeugenol was obtained from the Aldrich Chemical Co. and was
distilled before use, bp 138.5-140.5C (9 mm), [literature bp 1400C

(12 mm)].27
1H NMR (CDCI3, TMS): 1.82 (d, 3H), 3.80 (s, 3H), 5.72 (s, 1H), 5.76-

6.38 (m, 2H), 6.81 (s, 3H).
C NMR (CDC13, TMS): 18.27, 55.80, 108.05, 114.44, 119.31, 123.31,

130.81, 144.80, 146.65.








IR (neat, NaCl): 3540-3400 (s, br), 3015 (m), 2960 (m), 2935 (m),

2910 (m), 2880 (w), 2845 (m), 2730 (w), 1590 (m), 1510 (vs),
1462 (s), 1450 (s), 1423 (s), 1370 (m), 1260 (br, s), 1230 (s),
1205 (s), 1153 (s), 1120 (s), 1030 (s), 960 (m), 920 (w), 905

(w), 855 (m), 820 (m), 802 (m), 783 (m), 755 (w), 732 (w).
trans-Anethole/(E)-l-Methoxy-4-(l-propenyl)-benzene [4180-23-8] (42)
This material was purchased from the Aldrich Chemical Co. and
was used without further purification.
H NMR (CDC13, TMS): 1.82 (d, 3H), 3.73 (s, 3H), 5.92-6.42 (m, 2H),

7.01 (ABq, 4H).
1C NMR (CDC13, 77.0): 18.32, 55.12, 113.85, 123.30, 126.86, 130.37,

130.81, 158.64.
IR (neat, NaC1): 3029 (m), 3000 (m), 2955 (m), 2930 (m), 2910 (m),
2880 (w), 2835 (w), 2730 (w), 1650 (w), 1605 (s), 1575 (m), 1505

(vs), 1462 (br, m), 1440 (m), 1415 (w), 1375 (w), 1305 (m), 1280
(m), 1245 (s), 1210 (w), 1175 (m), 1110 (m), 1035 (s), 962 (m),
940 (m), 837 (m), 785 (m), 755 (m), 710 (w).
N-Ethylmaleimide/1-Ethyl-1H-pyrrole-2,5-dione [128-53-0] (43)

This monomer was purchased from the Aldrich Chemical Co. (Gold
Lable) and was used without further purification.
Diethylfumarate/(E)-2-Butenedioic acid, diethyl ester [623-91-6] (44)
Diethylfumarate (44) was obtained from the Bordon Chemical Co.
and was distilled from CaH2 under reduced pressure, bp 83.5-840C (4.3
mm) [literature bp 75C (5 mm)].36
H NMR (CDCl3, TMS): 1.33 (t, 3H), 4.28 (q, 2H), 6.82 (s, 2H).









Fumaronitrile/(E)-2-Butenedinitrile [764-42-1] (45)

This monomer was purchased from the Aldrich Chemical Co. Re-

crystallization of 45 from benzene gave white needles, mp 94-96.5C

(literature mp 95-970C).37

H NMR (CDC13, TMS): 6.29 (s, 2H).

N-Vinylimidazole/1-Ethenyl-1H-imidazole [1072-63-5] (46)

This monomer was purchased from Polysciences, Inc. and distilled

from CaH2 before use, bp 89-90C (17 mm).
H NMR (CDC13, TMS): 4.77-5.33 (AB of ABX, 2H), 6.89 (X of ABX, 1H),

7.07 (s, 1H), 7.18 (s, 1H), 7.66 (s, 1H).
1C NMR (acetone-d6, 29.8): 101.15, 116.55, 130.10, 130.30, 137.02.

Maleic Anhydride/2,5-Furandione [108-31-6] (47)

Maleic anhydride was obtained from Fisher Scientific Co. and was

sublimed at atmospheric pressure (800C) prior to use, mp 50.5-53C

(literature mp 52.80C).27

Homopolymers
Poly(N-Acetoxymaleimide) (48)

To a heavy-walled polymerization tube was added 2.021 g (0.0130

mol) of 11, 0.0211 g (0.128 mmol) of AIBN, and 25 mL of freshly dis-

tilled CH2C12. After all the solid had dissolved, the tube was de-

gassed (3 freeze-pump-thaw cycles) and sealed at -10-5 mm. Polymeri-

zation was carried out in a constant temperature bath (610C) for 66 h.

The tube was opened and the contents precipitated into ether. The

solid was collected, redissolved in dioxane and reprecipitated into

ether. The solid was again collected and dried in a vacuum oven

(1000C) overnight to afford 1.614 g (80% conversion) of pink powder (48).









H NMR (DMSO-d6, TMS): 2.34 (br-s, 3H), 3.45, 4.13 (br, 2H).

13C NMR (CD3CN-C12CHCHCI2, 600C, 1.30): 17.43, 42.19, 165.74, 169.05,

170.95.

IR (KBr): 2940 (w), 1820 (s), 1790 (s), 1730 (vs), 1625 (w), 1430

(w), 1373 (m), 1220 (s), 1160 (s), 1055 (m), 1000 (w), 820 (m),
725 (w), 640 (m).

Elemental Analysis: Calcd. for C6H5N04: C, 46.46; H, 3.25; N, 9.03.

Found: C, 45.74; H, 3.38; N, 8.88.

VPO (acetone): Mn = 3850 g/mol.

Poly(Phenyl N-Maleimidyl Carbonate) (49)
To a heavy-walled polymerization tube was added 3.143 g (0.01348

mol) of 13, 0.0250 g (0.152 mmol) of AIBN, and 6 mL of distilled ace-

tone. The tube was transferred to a high-vacuum line, degassed in
the usual manner and sealed at -105 mm. The polymerization was car-

ried out in a constant temperature bath (600C) for 89 h. The tube was

opened, and the solution was slowly added dropwise to a beaker of vig-

orously stirred ether. The precipitate was collected and dried in

vacuo giving 2.755 g (87% conversion) of pale-green solid (49).
1H NMR (CD3CN, 1.93): 3.99 (br, 2H), 7.32 (br, 5H).

1C NMR (CD3CN, 70C, 1.30): 42.92, 121.39, 128.50, 131.18, 150.63,

151.95, 169.49.

IR (KBr): 3060 (w), 2940 (w), 1825 (s), 1795 (s), 1735 (vs), 1600

(w), 1588 (m), 1490 (m), 1457 (m), 1375 (m), 1290 (m), 1225 (br,
vs), 1160 (m), 1115 (w), 1070 (s), 1020 (m), 1005 (m), 960 (m),

905 (w), 840 (w), 775 (m), 750 (m), 682 (m), 630 (m).









Elemental Analysis: Calcd. for C11H7N05: C, 56.66; H, 3.03; N, 6.01.

Found: C, 55.44; H, 3.11; N, 6.17.

Poly(N-Hydroxymaleimide) (50) from 48

To a 50 mL Erlenmeyer flask containing a stir bar was added 1.0 g

(0.0144 mol) of hydroxylamine hydrochloride and 20 mL of freshly dis-

tilled methanol. To the stirred solution was added 3.9 mL (0.0144

mol) of 3.7M sodium methoxide. After 0.5 h, the mixture was suction

filtered. To the filtrate was added a solution of 48 in CD3CN and

C12CHCHC12 (NMR sample -150 mg), the transfer aided by rinsing the

tube with acetone. The resulting mixture (pink ppt.) was stirred for

48 h, and the solvents were then removed in vacuo. Trituration of

the resulting solid with water gave pink solid which was suction fil-

tered and dried in vacuo.

C NMR (acetone-d6, 29.80): 42.03, 172.75.

IR (KBr): 3640-2300 (br, m), 3470 (br, m), 2920 (w), 2800 (w), 1785

(m), 1700 (br, vs), 1620 (m), 1470 (br, m), 1385 (w), 1340 (w),

1230 (s), 1120 (m), 1070 (m), 728 (m), 645 (m).

Poly(N-Hydroxymaleimide) (50) from 49

To a 50 mL round-bottomed flask containing a stir bar was added

1.411 g (6.05 mmnol of repeat units) of 49 and 20 mL of methanol. A

reflux condenser was attached, and the mixture was refluxed for 20 h.

The cooled solution was precipitated into 200 mL of benzene-pentane

(2:1). The solid was reprecipitated from acetone into ether, fil-

tered, and dried in vacuo, giving 0.605 g (88%) of tan powder (50).

The product decomposed above 2650C. The IR spectrum of this material

was identical to that of 50 derived from 48.









Elemental Analysis: Calcd. for C4H3N03: C, 42.49; H, 2.67; N, 12.39.

Found: C, 43.75; H, 3.40; N, 11.94.

Poly[N-(4-Carbethoxyphenyl)maleimidel (51)

To a heavy-walled polymerization tube was added 3.423 g (0.01396

mol) of 16, 0.0270 g (0.164 mmol) of AIBN, and 10 mL of freshly dis-

tilled DMF. When all the solid had dissolved, the tube was degassed

(3 freeze-pump-thaw cycles) and sealed at -10-5 mm. Polymerization

was carried out in an oil bath (750C) for 44 h. The tube was opened,

and most of the DMF was removed in vacuo. The resulting oil was dis-

solved in 5 mL of acetone and precipitated into ether. The solid was

reprecipitated from acetone into ether, collected, and dried in vacuo

to give 2.102 g (61% conversion) of pink solid (51).

1H NMR (acetone-d6, 500C, TMS): 1.36 (br, 3H), 4.33, 4.40 (br, 4H),

7.47, 8.08 (br, 4H).

C NMR (acetone-d6, 500C, 29.8): 14.55, 41.74, 45.64, 61.77, 127.47,

130.74, 136.44, 165.83, 175.82.

IR (KBr): 2985 (m), 2940 (w), 2910 (w), 1785 (sh, m), 1715 (vs),

1610 (m), 1510 (m), 1470 (w), 1445 (w), 1415 (sh, m), 1385 (s),

1280 (s), 1185 (s), 1110 (s), 1020 (m), 855 (m), 768 (m), 740

(m), 695 (m), 640 (m).

Elemental Analysis: Calcd. for C13H11N04: C, 63.67; H, 4.52; N, 5.71.

Found: C, 63.13; H, 4.67; N, 6.05.

Poly[N-(B-Vinyloxyethyl)imidazole](52)

All attempts to obtain homopolymer (52) of moderate molecular

weight and in good yield were unsuccessful. Low yields of oligomers

were generally obtained. Polymerization reaction conditions are de-

scribed in Chapter III, p. 97.









Copolymers
N-(B-Vinyloxyethyl)imidazole N-Hydroxymaleimide Alternating Copoly-
mer (53)

To a 100 mL round-bottomed flask was added 2.325 g (0.0168 mol)

of 28 and 39.95 mL (0.0168 mol) of 0.4 N HC1. Most of the water was

removed on a rotary evaporator at room temperature. The resultant

viscous oil was transferred to a heavy-walled polymerization tube

aided by a few mL of deionized water. Into a 5 mL volumetric flask

was placed 2.223 g (0.0143 mol) of 11, and the flask was diluted to

the mark with distilled THF. This solution was added to the polymeri-

zation tube (previously cooled to -780C), and the volumetric flask was

rinsed with 3 mL of THF. Finally, 0.0847 g (0.313 mmol) of K2S208 and

0.1237 g (0.315 mmol) of Fe (NH4)2(SO4)2.6H20 were added. The final

volume of solution was 22 mL. The tube was then degassed on a high-

vacuum line (3 freeze-pump-thaw cycles) and sealed at -10-5 mm. The

tube was placed in a 30.0C water bath for 91 h. The tube was opened

and the contents precipitated into CH3CN. The acetonitrile was de-

canted off, and the oily precipitate was taken up in 40 mL of 1 N HC1

and dialized (2000 MW retention) against deionized water for several

days. The precipitated solid was suction filtered and dried in vacuo

to afford 0.844 g (20% conversion) of light-brown solid (53).
H NMR: See Appendix, p. 122.

13C NMR: See Chapter III, p. 80.

IR (KBr): 3600-3320 (br, m), 3140 (m), 2940 (w), 1780 (m), 1705 (vs),

1575 (w), 1440 (w), 1400 (w), 1355 (w), 1290 (w), 1230 (s), 1105

(s), 1080 (s), 835 (w), 760 (w), 665 (w), 625 (w).









Elemental Analysis: Calcd. for C11H13N304: C, 52.59; H, 5.21; N,

16.73. Found: C, 49.78; H, 4.97; N, 14.68; S, 0.53.

VPO (DMSO): Mn = 488 g/mol.

Intrinsic Viscosity (0.1 N HC1, 30.0C): [n] = 0.112 dL/g.

Dichlorobis(1-[2-(ethenyloxy)ethyl]-1H-imidazole-N3) zinc-- N-Acetoxy-
maleimide Alternating Copolymer (54)

To a heavy-walled polymerization tube was added a solution of

0.327 g (2.40 mmol) of ZnC12 in 6 mL of distilled THF, followed by a

solution of 0.630 g (4.56 mmol) of 28 in THF (3 mL). To this solution

was added 0.703 g (4.53 mmol) of 11, 0.0075 g (0.046 mmol) of AIBN,

and 6 mL of THF. The solution was degassed on a vacuum line and
sealed at -10- mm. Polymerization was carried out at 700C for 3.5 h.

The white precipitate was filtered, washed with THF and dried in vacuo.

The material was extracted (Soxhelet) with THF for 3 days and dried in

vacuo, affording 1.110 g (67.5% conversion) of white solid (54) which

decomposed above 2200C.
13C NMR: See Chapter III, p. 89.

IR (KBr): 3640-3340 (br, m), 3135 (m), 2940 (m), 2880 (w), 1818 (s),

1785 (s), 1730 (vs), 1650 (br, w), 1522 (m), 1440 (m), 1370 (m),

1290 (w), 1220 (s), 1165 (s), 1110 (s), 1095 (s), 1065 (m), 950

(m), 830 (m), 755 (m), 655 (m), 625 (w).
Elemental Analysis: Calcd. for C26H30N6010'ZnCl2: C, 43.20; H, 4.18;

N, 11.63; C1, 9.81. Found: C, 42.35; H, 4.18; N, 10.98; C1,

9.22.
Intrinsic Viscosity (DMSO, 30.0C): [n] = 0.043 dL/g.









N-(B-Vinyloxyethyl)imidazole-- Fumaronitrile Copolymer (55)

To a heavy-walled glass polymerization tube was added 1.878 g

(0.0136 mol) of 28, 1.116 g (0.0143 mol) of 45, 0.0466 g (0.284 mmol)

of AIBN, and 25 mL of distilled CH2Cl2. The tube was transferred to

a high-vacuum line, degassed via several freeze-pump-thaw cycles and

sealed at 410-5 mm. The polymerization was carried out at 600C for

44 h, resulting in red solution containing an oily dark precipitate.

The tube contents were poured into ether. The oily precipitate was

taken up in acetone-methanol and precipitated into chloroform. The

solid was reprecipitated from acetone into carbon tetrachloride and

dried in vacuo (room temperature) overnight, affording 0.367 g of

mustard-brown powder. The mother liquors (from precipitations) were

combined and reduced in volume on a rotary evaporator. Precipitation

into chloroform gave an additional 0.525 g of dark-brown powder.

IR (KBr): 3150 (m), 2970 (m), 2940 (m), 2250 (m), 2200 (s), 2140 (m),

1620 (s), 1545 (m), 1440 (m), 1420 (m), 1355 (w), 1330 (m), 1290

(m), 1170 (m), 1080 (m), 1035 (w), 830 (m), 750 (m), 665 (m),

625 (m).

Elemental Analysis: Calcd. for C11H12N40: C, 61.10; H, 5.59; N,

25.91. Found: C, 60.53; H, 4.38; N, 28.62.

N-(B-Vinyloxyethyl)imidazole-- Diethylfumarate Copolymer (56)

To a polymerization tube was added 1.202 g (8.70 mmol) of 28,

1.199 g (6.96 mmol) of 44, 0.0114 g (0.0694 mmol) of AIBN and 25 mL

of distilled acetone. The tube contents were degassed (4 freeze-

pump-thaw cycles) and the tube sealed at 10-5 mm. Polymerization

was carried out at 600C for 90 h. The acetone solution was









precipitated into cold ether, and the gummy precipitate was dried in

a vacuum oven (50C, 48 h) to give 0.262 g of brittle solid (56).

1C NMR: See Appendix, p. 123.

IR (KBr): 3110 (w), 2980 (m), 2940 (m), 2905 (w), 2870 (w), 1730 (vs),

1595 (m), 1505 (m), 1465 (m), 1445 (m), 1370 (m), 1230 (br, s),

1175 (s), 1160 (s), 1095 (m), 1075 (m), 1025 (s), 905 (w), 855

(m), 815 (w), 740 (m), 660 (m), 620 (w).
Elemental Analysis: Calcd. for C15H22N205: C, 58.05; H, 7.14; N,

9.03. Found: C, 56.82; H, 7.11; N, 6.23.

Isoeugenol --Maleic Anhydride Copolymer (57)

To a dry heavy-walled polymerization tube was added 2.758 g

(0.0168 mol) of 41 and a solution of 1.652 g (0.0168 mol) of 47 and
0.0555 g (0.338 mmol) of AIBN in 10 mL of distilled acetone. The

solution immediately turned yellow in color. The tube contents were

degassed on a high-vacuum line and the tube sealed at -10-5 mm. Poly-

merization was carried out at 600C for 72 h. The viscous acetone

solution was added dropwise to a beaker of rigorously stirred CH2C12,

the precipitate filtered and dried in vacuo affording 2.725 g (62%

conversion) of white solid (57).
1C NMR: See Appendix, p. 124.

IR (KBr): 3580-3300 (m), 2965 (w), 2940 (w), 1855 (m), 1775 (vs),

1605 (m), 1515 (s), 1460 (m), 1430 (m), 1370 (m), 1275 (s), 1235

(s), 1215 (sh, s), 1155 (m), 1130 (m), 1080 (m), 1030 (m), 920

(s), 825 (m), 785 (w), 735 (w), 645 (w).
Elemental Analysis: Calcd. for C14H1405: C, 64.12; H, 5.38. Found:

C, 63.47; H, 5.61.









VPO (acetone): = 6950 g/mol.

Intrinsic Viscosity (acetone, 30.00C): [n] = 0.183 dL/g.

2-Propenylphenol -- Maleic Anhydride Copolymer (58)

To a dry heavy-walled polymerization tube was added 2.331 g

(0.0174 mol) of 40 and a solution of 1.703 g (0.0174 mol) of 47 and

0.0542 g (0.330 mmol) of AIBN in 10 mL of distilled acetone. The

solution became yellow, and the color persisted throughout polymeri-

zation. The tube contents were degassed and the tube sealed at ~10-5

mm. Polymerization was carried out at 600C for 44 h. The viscous

acetone solution was added dropwise to a beaker of vigorously stirred

CH2C12. The precipitate was filtered and dried in vacuo, affording

3.510 g (87% conversion) of white solid (58).

C NMR: See Appendix, p. 125.

IR (KBr): 3660-2500 (m, br), 1855 (m), 1770 (s, br), 1610 (m), 1585

(m), 1485 (m), 1455 (m), 1365 (m, br), 1225 (s), 1150 (s, br),

920 (m, br), 755 (s).

Elemental Analysis: Calcd. for C13H1204: C, 67.24; H, 5.21. Found:

C, 63.94; H, 5.69.
VPO (acetone): ~n = 21,200 g/mol.

Intrinsic Viscosity (acetone, 30.00C): [n] = 0.231 dL/g.

Isoeugenol -- N-[2-(4-Imidazolyl)ethyl]maleimide Copolymer (59)

A 25 mL three-necked round-bottomed flask fitted with a stir bar,

condenser, and gas inlet tube was assembled hot and cooled via flush-

ing with Ar. To the flask was introduced 0.3463 g (1.32 mmol of re-

peating units) of 57 and ~2 mL of distilled DMF. To this solution was

added 0.1707 g (1.54 mmol) of 20 in 0.5 mL of DMF. A white









precipitate was observed. The mixture was refluxed for 6 h and al-

lowed to cool. The viscous solution was added dropwise to a beaker

of rapidly stirred CHC13; the precipitate was filtered and dried in

vacuo. The product was subjected to Soxhelet extraction with CHC13

for 48 h and dried in vacuo, affording 0.473 g of off-white solid (59).

C NMR: See Appendix, p. 126.

IR (KBr): 3550-2500 (br, m), 3140 (m), 1765 (m), 1690 (s), 1615 (m),

1595 (m), 1510 (m), 1445 (m), 1400 (m), 1360 (m), 1270 (m), 1225

(br, m), 1160 (m), 1130 (m), 1080 (w), 1025 (m), 900 (br, w),

820 (m), 785 (m), 650 (w), 620 (m).

Elemental Analysis: Calcd. for C19H21N304: C, 64.21; H, 5.96; N,

11.82. Found: C, 58.75; H, 5.66; N, 10.68.

2-Propenylphenol--N-[2-(4-Imidazolyl)ethyl]maleirmide Copolymer (60)

Copolymer 60 was prepared from 58 by the same method as copoly-

mer 59 Thus, 0.383 g (1.65 mmol of repeat units) of 58 was com-

bined with 0.198 g (1.78 mmol) of 20 in refluxing DMF to give 0.470 g

of off-white product (60).


IR (KBr): 3650-2500 (br, m), 2960 (m), 1765 (m), 1690 (s), 1590 (m),

1483 (m), 1450 (m), 1400 (m), 1360 (m), 1255 (m), 1220 (m), 1160

(m), 1100 (m), 980 (w), 935 (w), 830 (w), 755 (m), 660 (w), 615

(w).
Elemental Analysis: Calcd. for C18H19N303: C, 66.45; H, 5.89; N,

12.91. Found: C, 62.00; H, 5.56; N, 10.55.









trans-Anethole-- Maleic Anhydride Copolymer (61)

To a polymerization tube was added 1.630 g (0.0166 mol) of 47,

0.0534 g (0.325 mmol) of AIBN, 2.464 g (0.0166 mol) of 42, and 10 mL

of distilled acetone. The tube contents were degassed in the usual

manner and sealed at -10- mm. Polymerization was carried out for

20 h at 600C. The gelatinous mass was dissolved in DMF and precipi-

tated into ether. The precipitate was filtered and dried in a vacuum

oven (900C, 1 mm) for 48 h, affording 2.065 g (50% conversion) of

white solid (61).
1C NMR: See Appendix, p. 127.

IR (KBr): 2960 (m), 2940 (m), 2840 (w), 1860 (m), 1780 (vs), 1610

(m), 1580 (w), 1510 (s), 1465 (m), 1440 (m), 1390 (w), 1335 (m),
1305 (m), 1255 (s), 1180 (s), 1080 (m), 1030 (m), 920 (s), 830

(m), 815 (sh, m), 738 (m).
Elemental Analysis: Calcd. for C14H1404: C, 68.28; H. 5.73. Found:

C, 68.11; H, 5.77.

trans-Anethole -- N-[2-(4-Imidazolyl)ethyl]maleimide Copolymer (62)

Copolymer 62 was prepared from 61 by the same method as copoly-
mers 59 and 60. Thus, 0.422 g (1.71 mmol of repeat units) of 61 was

combined with 0.200 g (1.80 mmol) of 20 in refluxing DMF to give 0.402

g of off-white product (62).


IR (KBr): 3440-2800 (br, m), 2940 (m), 2840 (m), 1770 (m), 1695 (s),
1610 (m), 1580 (w), 1510 (s), 1460 (sh, m), 1440 (m), 1400 (m),

1355 (m), 1300 (w), 1250 (m), 1180 (m), 1160 (m), 1105 (w), 1085

(w), 1030 (m), 975 (w), 930 (w), 830 (m), 730 (w), 660 (w), 615
(m).









Isoeugenol-- N-Ethylmaleimide Copolymer (63)

To a polymerization tube was added 1.5315 g (0.0122 mol) of 43,

0.0397 g (0.242 mmol) of AIBN, 2.010 g (0.0122 mol) of 41, and 10 mL

of distilled acetone. The tube contents were degassed and the tube

sealed at -10-5 mm. Polymerization was carried out at 600C for 38 h.

The acetone solution was added dropwise to a vigorously stirred beaker

of ether. The precipitate was filtered and dried in vacuo, affording

3.117 g (88% conversion) of white solid (63).
13C NMR: See Appendix, p. 128.

IR (KBr): 3680-3100 (br, m), 2970 (m), 2940 (m), 2880 (w), 2840 (w),

1770 (m), 1690 (vs), 1600 (m), 1510 (s), 1450 (m), 1405 (s),

1375 (m), 1350 (m), 1270 (m), 1225 (s), 1130 (m), 1030 (m), 940

(w), 895 (w), 860 (w), 810 (m), 790 (m), 770 (w), 730 (w), 650

(m).
Elemental Analysis: Calcd. for C16H19N04: C, 66.42; H, 6.62; N, 4.84.

Found: C, 65.66; H, 6.64; N, 5.03.

VPO (acetone): Mn = 25,200.

Intrinsic Viscosity (acetone, 30.00C): [n] = 0.276 dL/g.

2-Propenylphenol -- N-Ethylmaleimide Copolymer (64)

To a polymerization tube was added 1.8594 g (0.01486 mol) of 43,

0.0485 g (0.295 mmol) of AIBN, 1.994 g (0.01486 mol) of 40, and 10 mL

of distilled acetone. The tube contents were degassed in the usual

manner and the tube sealed (-10-5 mm). Polymerization was carried out

at 60C for 38 h. The acetone solution was added dropwise to ethyl

ether, the precipitate filtered and dried in vacuo, affording 1.286 g

(33% conversion) of white solid (64).








13C NMR: See Appendix, p. 129.

IR (KBr): 3660-3100 (br, m), 2975 (m), 2940 (m), 2880 (w), 1770 (m),

1695 (vs), 1605 (m), 1500 (m), 1485 (m), 1450 (s), 1405 (s),

1378 (m), 1350 (s), 1225 (s), 1135 (m), 1095 (m), 1040 (w), 935

(m), 850 (w), 830 (w), 810 (m), 755 (m), 680 (w).
Elemental Analysis: Calcd. for C15H17N03: C, 69.48; H, 6.61; N, 5.40.

Found: C, 67.01; H, 6.51; N, 6.25.
Intrinsic Viscosity (acetone, 30.00C): [n] = 0.083 dL/g.

Miscellaneous Reactions
Reaction of N-Acetoxymaleimide (11) and N-(B-Vinyloxyethyl)imidazole
(28). Preparation of N-Acetoxymaleimide Cyclotrimer (65)

To a 50 mL Erlenmeyer flask was added 4.038 g (0.0260 mol) of 11
and 10 mL of CH2Cl2. To this colorless solution was added a solution

of 0.0180 g (0.130 mmol) of 28 in 1 mL of CH2C12. Immediately a red

color became apparent which intensified with time. The flask was

allowed to stand at room temperature for 165 h. The dark-red solu-

tion was added dropwise to a beaker of vigorously stirred ether. The

precipitate was filtered and dried in vacuo at 100C to afford 0.66 g

(16.3%) of purple powder (65).
H NMR (CD3CN, TMS): 2.29 (br, ~3H), 3.00-4.60 (br-m, ~2H).
13C NMR: See Appendix, p. 130.

IR (KBr): 2945 (w), 1820 (s), 1790 (s), 1740 (vs), 1430 (w), 1375

(m), 1225 (s), 1160 (s), 1065 (m), 1005 (w), 820 (m), 670 (w),
645 (w).
Elemental Analysis: Calcd. for (C6H5N04)3: C, 46.46; H, 3.25; N,

9.03. Found: C, 46.40; H, 3.24; N, 9.03.









LRMS (m/e, rel. intensity): 465 (m 0.1), 423 (0.4), 113 (0.4), 60

(19.3), 45 (24.4), 44 (61.8), 43 (100).

VPO (acetone): Mn = 488 g/mol

Reaction of Maleic Anhydride (47) and N-(8-Vinyloxyethyl)imidazole (28)

To a 125 mL Erlenmeyer flask was added 0.967 g (7.00 mmol) of 28
and 20 mL of CH2Cl2. To this colorless solution was added 0.687 g

(7.00 mmol) of 47. The solution immediately turned yellow in color

and eventually became brown. The flask was allowed to stand for 11

days. The solution was decanted, leaving a black precipitate which

was removed from the flask and stirred with 100 mL of acetone for 3 h.

The solid was filtered and dried in vacuo, affording 0.897 g of brown

powder.

IR (KBr): 3650-2320 (br, m), 3140 (m), 2950 (w), 1770 (s), 1720 (br,

s), 1620 (m), 1580 (m), 1555 (m), 1445 (w), 1380 (br, m), 1220

(br, m), 1190 (m), 1135 (m), 1085 (m), 1035 (m), 935 (m), 830

(m), 750 (m), 665 (w), 625 (m).
Reaction of N-Hydroxymaleimide (14) and N-(B-Vinyloxyethyl)imidazole
(28)

To a 50 mL Erlenmeyer flask was added 0.326 g (2.88 mmol) of 14

and 10 mL of distilled acetone. To this pale yellow solution was

added 0.406 g (2.94 mmol) of 28. The solution immediately assumed a

darker yellow color, and a precipitate began to form. After stirring

for 20 h, the precipitate was filtered, washed with acetone and dried

in vacuo, affording 0.421 g of yellow solid which decomposed upon

heating to 1800C.









IR (KBr): 3140 (w), 3100 (w), 2940 (w), 1785 (m), 1695 (br, s), 1615

(m), 1570 (w), 1555 (w), 1540 (w), 1415 (w), 1360 (w), 1320 (w),

1235 (br, m), 1190 (m), 1080 (m), 955 (w), 830 (w), 740 (w),

690 (m).

Elemental Analysis: Calcd. for (C4H3NO3)3-C7H10N200H20: C, 46.06; H,

4.27; N, 14.14. Found: C, 45.92; H, 4.21, N, 13.96.

Kinetic Measurements

Equipment and Materials

Pseudo first-order kinetics were measured on Cary 17-D or Perkin-

Elmer 330 spectrophotometers. Temperature control was provided by a

Lauda K-2/R (40.0 0.20C) or a Haake A80 (25.0 0.20C) constant

temperature apparatus. A Corning-125 pH meter fitted with a Ag/AgCl

pH electrode was used to measure the pH of solutions before and after

the reaction with substrate. p-Nitrophenyl acetate (PNPA) was obtained

from the Aldrich Chemical Co. and was recrystallized from cyclohexane

before use, mp 77-78C (literature mp 81-820C).38 2,4-Dinitrophenyl

benzoate (DNPB) was kindly supplied by Ms. Ann Mobley.39 Deionized

water was distilled in glass before use. DMSO and THF were purified

as previously described. Tris(hydroxymethyl)aminomethane (Tris) was

obtained from Fisher Chemical Co. and was used without further purifi-

cation.

Kinetic measurements were carried out under two sets of condi-

tions: Method A for the catalysts imidazole, 50, and 53, and Method

B for catalysts 26, 59, 60, 62, 63 and 68.

Buffer Solutions

In Method A, two stock buffer solutions were prepared, 0.1M Tris









and 0.1M Tris-HC1, both having an ionic strength (y) of 0.1 (KC1).

The first solution was prepared by adding 12.114 g (0.100 mol) of Tris

and 7.455 g (0.100 mol) of KC1 to a 1 L volumetric flask and diluting

to the mark with distilled water. Tris*HCI was prepared by adding an

ampule of 0.1 N HC1 (Acculute), 12.114 g (0.100 mol) of Tris and 7.455 g

(0.100 mol) of KC1 to a 1 L volumetric flask and diluting to the mark

with distilled water. These two solutions were combined to give a

buffer solution of the desired pH. Thus a 2:1 volume ratio of Tris-

HCl:Tris gave a pH of 7.86 and a 3:1 ratio of Tris-HCl:Tris gave a pH

of 7.68 at 250C.

In Method B, two 80% DMSO:H20 (v/v) stock solutions were prepared,

both 0.02M in Tris or Tris-HC1, i = 0.02 (KC1). The first solution

was prepared by adding 1.2114 g (0.010 mol) of Tris, 0.7455 g (0.010

mol) of KC1, and 100 mL of distilled water to a 500 mL volumetric

flask and diluting to the mark with distilled DMSO. The second solu-

tion was prepared in the same manner, substituting 100 mL of 0.1N HC1

(aq) for 100 mL of distilled water. Again, the solutions were com-

bined to give buffer solution of the desired pH. Thus, a 4:1 volume

ratio of Tris-HC1:Tris gave a pH of 8.9.

Substrate Solutions

In Method A, a stock solution of PNPA (2.69 x 10 M) in aceto-

nitrile was used. In Method B, stock solutions of PNPA (1.60 x 10-3M)

in DMSO and DNPB (1.60 x 10-3M) in THF were employed.

Catalyst Solutions

In both Methods A and B, catalyst solutions were prepared accord-

ing to the concentration of functional groups. Due to difficulty in









determining the exact composition of copolymers, it was assumed that

the copolymers studied were strictly 1:1 alternating copolymers. The

contribution to the molecular weight by endgroups was also neglected

in all polymer catalysts. Thus, stock solutions of all copolymer

catalysts studied in Method B were -5.33 x 10-3N in repeat units dis-

solved in 0.02M Tris buffer of the desired pH.

Kinetic Method

The following paragraph describes the kinetic method using the

Cary 17-D spectrophotometer. The same procedure was used in conjunc-

tion with the Perkin-Elmer 330 spectrophotometer with the exception

that each sample cell required a corresponding reference cell. To

each of 6 -one cm path length quartz cells was added 3.0 mL of buffer

solution via pipet. To 4 of the cuvettes was added 150 pl of catalyst

solution via micropipet; to the other 2 cuvettes was added 150 i1 of

buffer solution. To one of the latter cuvettes was added 50 pl of

substrate solvent (CH3CN, DMSO, or THF), and it was placed in the

reference beam of the spectrophotometer. The remaining 5 cuvettes

were placed in the sample compartment to equilibrate thermally. The

sample cuvettes were then each charged with 50 pi of substrate solu-

tion, agitated by inverting the sample holder, and replaced in the

sample compartment. The release of p-nitrophenolate ion (Method A -

400 nm, Method B 416 nm) or 2,4-dinitrophenolate ion (Method B -

370 nm) was observed at constant wavelength at constant time intervals.

The reaction was followed for at least 10 half-lives as judged by

the constancy of the absorbance readings (A_). A plot of In (A~-At)

vs time (t) was constructed, and the negative slope of the best






59


straight line as determined by the least squares program of a Texas

Instruments TI-55-II calculator gave the desired rate constants

(kmeas). As kmeas is the sum of the catalyzed (kobs) and uncatalyzed
(kblank) rate constants, it was necessary to subtract kblank from

k means to obtain kobs. Furthermore, the second-order rate constant

(kcat) was calculated from the relation kcat = kobs/[catalyst]. In

the case of slow reactions where A_ was not obtained in a reasonable

time, kmeas was determined by the method of Kezdy and Swinbourne,

which is described in a monograph by Espenson.41















CHAPTER III

RESULTS AND DISCUSSION

As was stated in Chapter I, alternating copolymers containing

pendant groups which would exhibit cooperative behavior in the hydrol-

ysis of an ester substrate were sought. It was decided to utilize

substituted vinyl ether and maleimide monomer pairs in order to achieve

the desired alternation of pendant functional groups, as this combina-

tion of monomers is known to give regularly alternating copolymers

under free-radical initiation conditions.1 The selection of catalyt-

ically active functional groups was made possible by the work of

Kunitake et al.6'4244 In these studies, it was shown that the hydrox-

amic acid group is an excellent acylation catalyst for activated ester

substrates. However, decomposition of an acylhydroxamate is a slow

process. In order to obtain a useful catalyst, i.e., one with effi-

cient turnover of the catalytic group, the deacylation rate must be

comparable to the acylation rate. Kunitake and Okahata6 found that

introduction of an imidazole group into the polymer will accelerate

the deacylation process. It was concluded that the imidazole group

assists deacylation of the acylhydroxamate intermediate either by

acting as a general base or as a nucleophilic catalyst as depicted

below.





61




0 H 0
4N O-0-H,_: H N H +. H
Ph OCH3 Ph O-
0 + CH COOH

or




O 0
N \ 1-- 4 H N CH3 X+.>H
Ph OCCH Ph 0 0
11 3
0


H2O


CH3COOH + N 0 N H

Ph OH



With this information in mind, the synthesis of maleimide and

vinyl ether monomers substituted with imidazole and hydroxamic acid

functionalities was initiated. Initial effort was directed at attach-

ing an imidazole group to a maleimide; however, due to the base sensi-

tive nature of maleimides,45 it was decided that the hydroxamic acid-
maleimide combination would be more comparable. This logic dictated
that the complementary vinyl ether monomer should contain an imidazole

group. In the next section are described several strategies to carry


out this objective.









Imidazole --Maleimides
Our initial attempt to prepare an imidazole maleimide is out-
lined schematically below.


02N H2N
N HNO N H
r{\ ^ -, -- _"._ n
H2SO4 2
H H H
39

47

0 0 0 H 0
-H20 /


H H



34
Imidazole was nitrated via a literature procedure34 to afford 4-
nitroimidazole (39). We envisioned obtaining the desired N-(4-imida-
zolyl ) maleimide via reaction of 4-aminoimidazole with maleic anhy-
dride (47) followed by dehydration of the resulting maleamic acid.
This attempt was thwarted by the inability to obtain 4-aminoimidazole
from reduction of 39. Indeed, 4-aminoimidazole is very unstable and
has been isolated only as dihydrochloride and sesquipicrate salts.46
Our attempts to convert 39 to 4-aminoimidazole are outlined in Table II.
In lieu of 4-aminoimidazole, the reactions of histamine (20) and
2-aminothiazole with maleic anhydride were carried out. Although the
maleamic acids were obtained in reasonable yield, attempts to effect










TABLE II

Hydrogenation of 4-Nitroimidazole (39)


Reaction Conditions Work Up Comments


H2/5% Pd on C DMSO solution diluted black tar obtained
DMSO/1 atm. with ether, treated
with anhy. HC1

H2/10% Pd on C DMSO solution diluted black tar obtained
DMSO/-4 atm. with benzene, treated
with anhy. HC1

Fe/HC147 benzene solution black tar obtained
benzene treated with anhy. HC1

3% Na(Hg)48 added Hg(OAc)246 gray solid obtained
methanol



dehydration to the corresponding maleimides by the method of Searle49

were unsuccessful.


H2N N

20





H2N + 47
2-


+ 47


0
OH


0 S









Another strategy to synthesize N-[2-(4-imidazolyl)ethyl]malei-
mide is outlined below.


0 0
H

H H
8 0


SI-H20
0 0 0

0 ~HN H







Reaction of the furan-maleic anhydride Diels-Alder adduct (8) with
20 afforded compound 24 in good yield. Dehydration of this succinamic
acid derivative was also unsuccessful using the Ac20/NaOAc49 and N,N-
dicyclohexylcarbodiimide (DCC)/DMF50 procedures.
Hydroxamic Acid --Maleimides
The simplest hydroxamic acid --maleimide is N-hydroxymaleimide
(14). The acidity of hydroxamic acids is comparable to the acidity of
carboxylic acids;51 thus, one would expect hydroxamic acid groups in-
corporated into a polymer to be significantly ionized in neutral or
basic media. As N-hydroxysuccinimide has a pka of -6.0,52 it was be-
lieved copolymerization of 14 would fulfill the hydroxamic acid re-
quirement.









Ivanov et al.53 reported the synthesis of 14, and we attempted to

duplicate this synthesis as outlined below:




OH
0 0 NH OH I 14


47 17 ON
C N-OH

66

Treatment of maleic anhydride (47) with hydroxylamine afforded

N-hydroxymaleamic acid (17) in 60% yield. We attempted dehydration

of 17 using the Ac20/NaOAc49 and P20 /DMF50 methods, but were unable

to isolate 14. Narita et al.50 had also studied the dehydration of

17 using the following reagents: P205, SOC12, Ac20, p-toluenesulfonic

acid, DCC, and acetyl chloride in pyridine. Reaction of 17 with P205

in DMF gave N-hydroxyisomaleimide (66) and not 14 as reported by

Ivanov et al. Neither 14 or 66 was obtained by Narita et al. using

the other above mentioned dehydration reagents.

In another publication by Narita et al.15 was described the syn-

thesis of N-acetoxymaleimide (11). We felt this monomer would better

suit our needs than 14 itself. It has been observed by Kunitake

et a.43 that polymerization of monomers containing unprotected hydrox-

amic acid groups is difficult, because the hydroxamic acid group is

tautomeric with the nitrone structure, and nitrones are efficient

free-radical trapping agents.










/OH OH 0
-C-N = -C=N
R R

hydroxamic acid nitrone

Therefore, it seemed advisable to use a maleimide containing a
protected hydroxamic acid group for polymerizations. Protected male-

imide (11) was synthesized via the steps outlined below. The yields
indicated are those obtained in this laboratory.

0 0

+ 0 +- OH 88%

47 8
NH20H
MeOH
0 0 75%

d)-OAc Ac20 -OH 65%

10 0 9 0



25 mm 82%
82%
N
OAc
11
The reverse Diels-Alder reaction of N-substituted maleimide
adducts of furan is a powerful method for synthesis of N-substituted
maleimides which cannot be obtained from the direct dehydration of the
corresponding maleamic acids. Indeed, isomaleimide formation was not

a side reaction in this synthesis.









The preparation of N-hydroxymaleimide (14) itself was described

in two publications by Akiyama et al.17,54 This synthesis also em-

ployed the furan-maleic anhydride Diels-Alder adduct as a means to

obtain maleimide (13), the methanolysis of which gave 14. The reac-

tion scheme along with yields obtained in this laboratory is outlined

below.




0 0 0 0

-OH OCOCl
OY-oH -00COCOCOPh 56%
DMF, EtN h 56%

9 0 12


bromo-
benzene
0 1600C

OH MeH -OCOPh
0-H -H-- I-0 OPh-
0 43% 0 82%

14 13



Carboxylic Acid --Maleimides

The carboxylic acid group has been incorporated into synzymes55,56

and also plays a key role in the "charge-relay system" of the natural

enzyme chymotrypsin.57 We attempted the synthesis of carboxylic acid

containing maleimide monomers for two reasons: evaluation of bifunc-

tional synzymes containing the carboxylic acid residue, and conversion
58
of the carboxylic acid group via its N-hydroxysuccinimide ester5 to a

hydroxamic acid group.







The direct dehydration of maleanilic acids 22 and 23 were unsuc-
cessfully carried out using the following reagents: Ac20/NaOAc,49
DCC/DMF,50 DCC/CH2C2 59 and refluxing xylene.60 On the other hand,
maleanilic acid 15 was cleanly dehydrated to maleimide 16 in 83% yield
using Ac20/NaOAc.



0 0 0 1 O 00
OH NH 0 H H H

0 0 0 0
CO2H CH2CO2H CO2Et CO2Et
22 23 15 16


Clearly, the presence of the second carboxyl group in 22 and 23
is in some way responsible for the inability to effect dehydration.
Other workers61 have reported on the inability to dehydrate amino acid-
maleamic acids, and the synthesis of maleoylamino acids by modification
of maleimide itself has only recently been reported.20'62 Using this
former procedure, N-carbethoxymaleimide (18) was synthesized in 44%
yield.



C C02C2Et
0 Et O, 0C o0
H C02Et








Imidazole -- Vinyl Ethers
Although imidazole substituted vinyl ethers have not been re-
ported in the literature, we were able to synthesize these compounds
in some cases via modification of standard procedures. Our first
attempt involved the vinyl transetherification reaction as reported
by Watanabe and Conlon.63

or N

cat. Hg(OAc)2 ( )
H H


Thus, 2-benzimidazole methanol was treated with an excess of ethyl
vinyl ether or n-butyl vinyl ether at reflux in the presence of a
catalytic amount of mercuric acetate. 1H NMR analysis of the reaction
mixtures (upon removal of excess vinyl ether) indicated that no reac-
tion had taken place. A possible explanation for the failure of the
desired reaction to work was the observation that 2-benzimidazole
methanol was largely insoluble in both ethyl vinyl ether and n-butyl
vinyl ether.
A different approach to this class of compound was more fruitful.


1) K, THF
0 2)
H CDMSO
28

Alkylation of the potassium salt of imidazole with 2-chloroethyl vinyl
ether (CEVE) in DMSO afforded desired N-(B-vinyloxyethyl)imidazole (28)








as a colorless oil in 46% yield. Vinyl ether (28) was also synthesized
via the sodium salt (NaH) of imidazole, albeit in lower yield (25-30%).
Although 28 is a tertiary (N-substituted) imidazole, it was believed
that the position of substitution would not significantly hinder this
compound's ability to catalyze deacylation of the acylhydroxamate in-
termediate in esterolysis reactions.42
A 4(5)-substituted imidazole --vinyl ether, B-vinyloxyethyl(imida-
zol-4ylmethyl)piperidinium chloride (30), was synthesized, and its
ability to copolymerize with maleimide (16) was studied.


Cl-

Cla N I MeOH
Cl 1 -HC1 + 2 H
H N


31 29 30

Reaction of N-(B-vinyloxyethyl)piperidine (29) and 4-(chloromethyl)-
imidazole hydrochloride (31) gave 30 in yields of 70-80%. Vinyl ether
30 proved very difficult to purify, requiring repeated treatment with
Na2CO3 in methanol and precipitation into ethyl ether to remove excess
29 as its free base. Furthermore, 30 was isolated as a gummy hygro-
scopic solid, and attempts to isolate 30 as its hydrochloride salt re-
sulted in rapid hydrolysis of the vinyl ether group. Vinyl ether 30
was consequently used for copolymerization studies in free base form.
Despite prolonged drying in vacuo, a major contaminant in 30 was
ethyl ether as determined from 1H NMR.








Another attempt at preparation of a 4(5)-substituted imidazole--

vinyl ether is outlined below.




1) Mg, THF V N
SO C1 72) 31

H
67

The covalently bound chlorine atom in 31 is extremely labile to nucleo-

philes as reported by Turner et al.29 It was postulated that vinyl

ether 67 could be obtained by slowly adding 31 to a solution of 2-

chloroethylmagnesium chloride. The free base of 31 is not stable,

presumably due to self-condensation, which necessitated the use of 31.

However, CEVE reacted with Mg turnings in THF to give an insoluble

Grignard reagent. Addition of 31 resulted in no 67 being formed.

Other Imidazole Monomers

A search for other imidazole containing monomers which might

alternately copolymerize with N-substituted maleimides was conducted.

Convinced that the reaction of a Grignard reagent with 31 as described

above should work, the reaction of vinylmagnesium bromide with 31

afforded 4-allylimidazole (38) in 45% yield.


1) Mg, THF
SBr 2) 31 /









This compound had previously been synthesized and characterized by

Begg etal.33 from the pyrolysis of N-allylimidazole, giving approxi-

mately equal amounts of 2- and 4-allylimidazole. Our synthesis thus

represents a new and regiospecific method of obtaining 38. In view of

the report that allylphenols and N-substituted maleimides copolymerize

in alternate fashion,11 copolymerization studies with 38 were carried

out.

It was postulated that N-substituted maleimides might also alter-

nately copolymerize with vinyloxycarbonyl-substituted imidazoles, due

to similarities in structure between vinyl ethers, vinyl esters, and

vinyl carbamates. An empirical comparison of monomer reactivities can

be found in the Q-e scheme introduced by Alfrey and Price.64 The e

value, which is a measure of monomer polarity, is positive for elec-

tron-deficient olefins such as N-phenylmaleimide (e = +3.24) and nega-

tive for electron-rich olefins such as CEVE (e = -1.58), vinyl acetate

(e = -0.88), and vinyl N,N-diethylcarbamate (e = -1.10).65 The reac-

tion of histamine (20) and vinylchloroformate (VOC-C1) was therefore

studied.

The reaction of 20 and VOC-Cl was carried out in organic solvents

in the presence of an organic base over a range of temperatures.




VOC-C1 0 0
solvent, RN 6-38%
20 -_430 15C 3 H 76-38%

37









In each case, the major isolable product was a diacylated hista-

mine as evidenced by mass spectrometry (M = 251), 1H NMR (presence

of 2 ABX patterns), and 13C NMR (11 resonances). In the IR spectrum,

carbonyl stretching frequencies were observed at 1775 and 1735 cm-1

There are three sites on 20 which might be acylated, N N and

N 66




H


Difficulty was encountered in determining the sites of substitution.

Structure 37 was tentatively assigned as the Na, NT isomer, although

the N", N' and N", Na structures cannot be ruled out. The IR carbonyl

stretching frequencies were especially disturbing in view of the car-

bonyl stretch (1710 cm- ) observed for the monoacylated histamine (35).

In Table III is reported the conditions and yields obtained in the

reaction of 20 with VOC-C1.

TABLE III
Acylation of Histamine (20) with VOC-C1

20(equiv) VOC-C1 (equiv) Solvent Base (equiv) T (C) %Yield 37a

1.0 1.0 dioxane Et3N (1.0) 12-14 6.2

1.0 0.95 CHC13b Et3N (0.95) 0-5 38

1.0 0.95 CHC13 0 22

1.0 0.95 CHC3b Et3N (0.95) -43 33

1.0 0.95 CHCI3 pyridine (XS) -43
a yield based on VOC-C1
bethanol-free CHC13









When the reaction of 20 and VOC-C1 was carried out under aqueous

conditions, the monoacylated histamine 35 was obtained in low yield.


3.0 equiv.NaHCO3 0-
202HC1 H-dioxane NH
VOC-C1, 00C N
2%
35
H
Evidence for structure assignment is based on mass spectrometry (M =

181), 1H NMR (broad one proton signals at 5.67 and 9.19 ppm), and 13C
NMR (8 resonances). When 35 was heated above its melting point, a

reaction involving displacement of a vinyloxy group took place.


H 0 2 S 2
N-"N\ N



36 zapotidine

This compound was assigned structure 36 on the basis of mass spectro-

metry (M+ = 137), 1H NMR (loss of vinyl signals), and 13C NMR (6 reso-

nances). Furthermore, H-2 (the proton flanked by both nitrogen atoms

of the imidazole ring) appears further downfield (8.04 ppm) than usual.

Comparison with the 1H NMR spectrum of zapotidine (H-2 = 8.42 ppm)

confirms that the downfield resonance of H-2 can be attributed to the

deshielding effect of the carbonyl group.67 No copolymerization stud-

ies were conducted with 35 due to difficulties in obtaining sufficient

quantities to work with. It was also suspected that 35 rearranged to

36 while being chromatographed on silica gel.









Copolymerization of Maleimides with N-(B-Vinyloxyethyl )imidazole (28)

Addition of 28 to a CH2C 2 solution of 11 resulted in the imme-

diate appearance of a blood-red color which intensified with time. No

color change occurred when CEVE was added to a solution of 11. The

red color was also apparent in solutions of N-vinylimidazole (46)--

11 and N-methylimidazole-- 11, suggesting that the imidazole group was

responsible for the red coloration. After appreciable reaction times,

the red solutions were precipitated into hexanes or ether-giving pale-

red solids in each case. Evaporation of the filtrate in vacuo gave an

oil whose 1H NMR spectrum revealed a preponderance of N-substituted

imidazole over 11. The red solids appeared to be the same substance

as judged from their IR spectra (1820, 1790, 1740, 1225, 1160 cm-')

and appeared to be the homopolymer of 11. The belief that N-substi-

tuted imidazoles were catalyzing homopolymerization of 11 was demon-

strated by carrying out the reaction using 0.5 mol% of 28.



OAc

0
0 0 0.005 equiv. 28. AcO- 16%

1 0
S3 N0
0
OAc
11 65

Further insight as to the structure of 65 was gained by determin-

ing the molecular weight by VPO (fn = 488). This information revealed

that 65 was most likely a trimer of 11.









A search of the literature revealed that this reaction had been

reported previously, and the major product was a maleimide cyclotri-

mer.68 Wagner-Jauregg and Ahmed69 invoked a zwitterionic mechanism

to account for the observed product.






R1 R R R
N.
0 0-




+ 2 x iR

0


0 R R
0 0


R0 R


0 R 0
R

Furthermore, in addition to the desired Michael adduct, 1-25% of male-

imide cyclotrimer was formed when imidazole was reacted with N-substi-

tuted maleimides in stoichiometric amounts.68











=Lmaleimide
H + 0 0 R cyclotrimer

R 0N



Although this information was disconcerting as far as our copoly-

merization strategy was concerned, we nevertheless attempted the co-

polymerization of 11 and 28 using AIBN as initiator. Not surprizing-

ly, only homopolymers of 11 were obtained. Direct copolymerization

of maleimides 13 and 14 with 28 were also unsuccessful.

Recognizing that the cyclotrimerization reaction was responsible

for the inability to obtain alternating copolymer, ways were sought to

circumvent this side reaction. It was reasoned that reaction of 28

with a Lewis acid would effectively retard the imidazole residue's

ability to catalyze cyclotrimerization.



PG N-PG

28

AIBN



n n

-PG









The ideal protecting group (PG) would coordinate strongly enough with

the imidazole moiety to preclude cyclotrimerization yet be easily re-

moved following copolymerization. The hydrochloride salt of 28 might

afford adequate protection, however when 28 was treated with anhydrous

HC1 in ether or THF solution, oligomerization of 28 occurred with con-

comitant cleavage of the vinyl ether.




n OH
anhyd. HC1 or C1
28 -
S THF or Et20



+ C
N
H


Reaction of 28 with chlorotrimethylsilane (Me3SiC1) in THF might

also be expected to provide protection.


Me3SiCI N
28 Me3SF ) "N- SiMe3
THF
C1


In these experiments, either 28 or 46 was allowed to react with 1.0

equivalent of Me3SiC1 in THF in a polymerization tube under N2. A

solution of 11 or 13 and AIBN in THF was subsequently added. The

appearance of a pink color probably indicated that the N-Si bond was

too labile to afford adequate protection. Homopolymers of 11 and 13

were obtained in low yields.









Vinyl ether 28 and maleimide 11 were successfully copolymerized

when 28 was pretreated with 1.0 equivalent of aqueous HC1. Maleimide

11 was added in acetone or THF solution to give a homogeneous mixture.

Polymerization was initiated via redox conditions, K2S208 and an Fe(II)

salt.


n
28 + 11 1.0 equiv. HC1 (aq)
H 0-THF
K2208,,Fe(NH4)2(SO4)2-6H20 0 -20%
30C, 90 h
0- N


53 H
The copolymer was purified by precipitating the reaction mixture into

acetone (to remove maleimide homopolymer), redissolving the oily pre-

cipitate in aqueous HC1 and dialyzing this solution against deionized

water. Copolymer 53 precipitated from solution during dialysis. The

IR spectrum of 53 indicated the presence of both monomers, carbonyl

stretching frequencies at 1780 and 1705 cm-1 (indicating that the N-

acetoxy group had been hydrolyzed) and C-O-C ether stretch at 1105

cm-1 The carbonyl absorbances for 53 are identical to those reported

for N-hydroxymaleimide --styrene copolymer.70 Evidence for alterna-

tion can be found in 13C NMR spectrum of 53 (Figure 1). In the carb-

onyl region appear 3 peaks in area ratios of ~2:1:1. This is consist-

ent with an alternating copolymer with a homogeneous sequence distribu-

tion whose stereochemistry at the succinimide unit is exclusively cis

or trans and whose carbonyls can "see" relative stereochemistry two

bonds distant. Carbon 10 can be assigned as the upfield doublet










E
CL







.J



o









0
S r-
i

o
O









0
Co


































u
0L
Cn













Ci




















Ss-
U
C




0

CL
0









4 -










u-
U-








0 j









reflecting random relative stereochemistry between C-2andC-3. Carbon

11 then appears as a singlet as a result of its inability to "see"

relative stereochemistry three bonds distant. The carbonyl region of

53 is analogous to the carbonyl region of N-phenylmaleimide --2-chloro

ethyl vinyl ether alternating copolymer as reported by Olson.12 In-

deed, a more complete explanation of this reasoning can be found in

this work.12

The assignment given carbonyl carbons 10 and 11 can also be ra-

tionalized by empirical chemical shift parameters first reported by

Grant and Paul.71 Substituents other than protons which are situated

a or B to a carbon of interest cause a downfield shift (-9 ppm) rela-

tive to a similar compound without substitution. Substituents other

than protons which are situated y to a carbon of interest cause an

upfield shift (~2 ppm). Examination of the copolymer structure re-

veals that carbons 10 and 11 have equal numbers of a and 3 substituents.

Carbonyl 10, however, has an addition y substituent by virtue of

branching at C-2. Therefore, C-10 should appear further upfield than

C-11.

The resonances between 120 and 140 ppm were assigned to the car-

bons of the imidazole ring. The signal appearing furthest downfield

was assigned to C-9, while no distinction could be made between C-7

and C-8.

The resonances between 70 and 80 ppm are typical for carbon atoms

alpha to an oxygen atom. Differentiation between C-2 and C-5 could be

made after examination of an off-resonance spectrum (Figure 2). The

signal furthest upfield appeared as a triplet (C-5) and the downfield






















C-)

CD




CD


.0
U3
rL
0
O










Co

Q.-


C-
U

-1 -


E

-


a


Ji
Co









signal as a doublet (C-2). Carbon-6 also appeared as a triplet in the

off-resonance 1C spectrum.

Further evidence for alternation can be obtained from the chemi-

cal shifts of the succinimide backbone carbons, C-3 and C-4. In the

1C NMR spectrum of N-hydroxymaleimide homopolymer (50), the backbone

carbons appear as a broad singlet centered at -42 ppm. In copolymer

53 the succinimide backbone carbons appear as two signals at -39 and

-48 ppm. Carbon-4 was assigned to the upfield signal on the basis of

having one additional y substituent vs. C-3. In addition, C-3 has one

additional 6 substituent than does C-4. The broad hump appearing be-

tween C-3 and C-4 at -42 ppm is probably attributable to the methine

carbons of homomaleimide sequences. The methylene backbone carbon

atom (C-1) was assigned to the signal appearing furthest upfield.

Copolymer 53 possesses very interesting solubility characteris-

tics. As isolated, 53 is virtually insoluble in all common organic

solvents, although it will dissolve in DMSO at elevated temperatures.

Interestingly, 53 is water soluble at pH <3.6 and pH >7.1 but insoluble

between these limits. This solution behavior led us to believe that

53 is a polyampholyte.





n n n


N N 0 N N
I II-
OH 0 0

H H
H H










Solubility is attained when the copolymer is protonated or deprotonated

giving rise to net positive or negative charges. Under these condi-

tions, 53 might be expected to behave as a polyelectrolyte. At the

isoelectric point, however, the attraction between oppositely charged

side chains should result in tight coiling, hence a lack of solubility.

In this case, an increase in the ionic strength of the medium should

lead to expansion of the chains and impart water solubility. Such be-

havior has been noted for poly(vinyl imidazolium sulphobetaine) (PVISB)

by Salamone et al.72

The solubility of 53 in various salt solutions is shown in Table

IV. It can be seen that certain salts are more effective than others

with respect to dissolving power. Interestingly, both sat. LiC1 and

sat. LiBr completely dissolve 53, while 5.0 M LiC1 only partially dis-

solves 53. It is also not clear why 53 is soluble in sat. Nal, par-

tially soluble in sat. NaC1, and apparently insoluble in sat. NaBr.

TABLE IV

Solubility of 53 in Salt Solutions

Anion ....
Cation ion C1 Br I BF4

.+ sat. +
Li+ sat. + sat. +
5.0M P

Na sat. P sat. sat. +
3.0M P

K sat. P sat. sat. -

sat. = saturated solution
+ = soluble
= insoluble
P = partially soluble










Salamone et al.72 found that large cations, e.g. K and large anions,

e.g. C104 were more effective solubilizing ions than were smaller

ions. Minimum salt concentrations were of the order of 0.03-0.52M

for PVISB, while saturated salt solutions were necessary to impart

solubility to 53.

Determination of the molecular weight of 53 proved difficult, and

the results were ambiguous. VPO analysis in DMSO at 1000C gave M n

500 g/mol. It is believed that this number represents a minimum value

as 53 was observed to decompose under similar conditions in the NMR

probe. As VPO is a colligative technique, the presence of decomposi-

tion fragments would result in a lower Mn than expected. A maximum

molecular weight value was calculated from end group analysis (elemen-

tal analysis for S). Presumably the initiating species in the redox

system employed is the sulfate radical anion.73

52082- + Fe+2 S042- + s04 + Fe+3


Assuming the incorporation of one sulfate group per polymer chain,

from calculation of an empirical formula a molecular weight of s 6000

g/mol was derived.

The intrinsic viscosity [n] of 53 was determined in 0.1N HC1 at

30.0C to be 0.112 dL/g. Although this value cannot be directly re-

lated to molecular weight, it is an indication of the hydrodynamic

volume of 53. Of course the size of the polymer chains should vary

with the pH of the medium, and one would expect a change in [n] de-

pendent on the degree of ionization of imidazole groups.









Gel permeation chromatography of 53 revealed two components in a

3:1 area ratio, the larger component having the shorter retention

volume. The presence of two components precluded accurate molecular

weight determination, as the individual viscosities could not be de-

termined independently. It was suspected that the minor component was

attributable to N-hydroxymaleimide homopolymer (50), which we were un-

able to separate from 53.

In another set of experiments, 28 was mixed with ZnCl2 in THF

before addition of AIBN and 11. In this case, a white-THF insoluble

powder was obtained after only a few hours at 60C. The IR spectrum

of this material indicated that both 11 and 28 had been incorporated

as evidenced by carbonyl stretching frequencies at 1818, 1785 and 1730
-1
cm and C-O-C ether stretch at 1110 and 1095 cm-. The incorporation

of ZnC12 into this material was inferred by elemental analysis for C1

(9.22%). Elemental analysis was reasonably consistent with a struc-

ture containing two equivalents of 28 and two equivalents of 11 per

equivalent of ZnCl2.

Reaction of 28 with four equivalents of ZnC12 in ethanol gave,

after dilution with ether, an 89% yield of 33, mp 78.5-80C.


4.0 equiv. ZnC12 ZnC

-2
28 EtOH < 0 ZnC2

33


The stoichiometry of this complex was determined from elemental analy-

sis and is consistent with N-alkylimidazole -- ZnCl2 complexes studied

by Welleman et al.32 On the basis of the structure of 33 and the









elemental analysis data for the ZnCl2 copolymer, the latter's repeat-

ing unit was assigned structure (54).


54

This crosslinked structure accounts for the insolubility of 54 in
common organic solvents. However, 54 dissolves in warm DMSO (~600C),

presumably giving a DMSO-ZnC274 complex and free copolymer. The [n]
of a DMSO solution of 54 at 30.00C was equal to 0.043 dL/g. Copolymer
54 is also soluble in water at pH >13 (NaOH) and pH <3.5 (HC1).


\ *Cl









The proton decoupled 13C NMR spectrum of 54 is shown in Figure 3.

Similarities to the 13C NMR spectrum of 53 (Figure 1) are apparent,

and the assignment of carbon atoms is the same as in 53. Two addi-

tional peaks one in the carbonyl region and one at -22 ppm can

probably be assigned to acetic acid (from hydrolysis of the N-acetoxy

group). The resonance at -42 ppm most likely indicates the presence

of homomaleimide sequences.

Copolymerization of Fumaronitrile (45) and
Diethylfumarate (44) With N-(3-Vinyloxyethyl)imidazole (28)

In view of the fact that 28 would not cleanly copolymerize with

11 or 13, it was decided to attempt copolymerization of 28 with fuma-

ronitrile (45) and diethylfumarate (44). As both latter monomers are

electron deficient, 45 (e = +2.73)65 and 44 (e = +2.26),65 it was be-

lieved copolymerization with vinyl ether (28) might afford alternating

copolymers. Indeed, alternating copolymers have been obtained from

copolymerization of both 45 and 44 with N-vinylcarbazole (e =-1.29).65

It was envisioned that hydroxamic acid groups could be introduced

following copolymerization via transformation of the nitrile and es-

ter groups.

Copolymerizations of 28 with 44 and 45 were carried out in solu-

tion at 600C using AIBN as initiator. Low yields of low molecular

weight copolymers were obtained in each case. The 1H NMR spectrum of

56 indicated that the copolymer was rich in diethylfumarate (-2.3:1)

as determined by comparing the integration of methyl protons to imida-

zole protons. These data are supported by elemental analysis for ni-

trogen, the value obtained being -2.8% lower than expected for a 1:1
















Q.











0
o

0 D









0
co

---











- '-








0


4-
0






.-
O
O













4U
0
u
4,





0









S..
1 U
N0




+-
01
s-
0











14















Sacetone
28 + 44
AIBN
600C, 90 h







CH2C12
28 + 45 A
60C, 44 h
60C, 44 h


CO2Et
m
fn CO2Et




N
0 56
NC




CN




55


copolymer. Copolymer 55 was suspected of being rich in fumaronitrile

on the basis of nitrogen analysis, found to be -2.7% higher than ex-

pected for a 1:1 alternating copolymer. Since alternating copolymers

were not obtained in either case, no attempt was made to transform

either the nitrile or ester group to a hydroxamic acid group.

Copolymerization of Maleimide (16) With
B-Vinyloxyethyl(imidazol-4ylmethyl)piperidinium Chloride (30)

After it had been established that copolymer (53) was not an

efficient catalyst, new catalysts were sought. It was proposed that

a better catalyst could be obtained by changing the nature of the hy-

droxamic acid group and by varying the position of substitution on

the imidazole ring. Our strategy involved copolymerizing a 4(5)-

imidazole-substituted vinyl ether with an ester-maleimide and convert-

ing the ester group to a hydroxamic acid group following the copoly-


merization step.




Full Text

PAGE 1

BIFUNCTIONAL SYNZYMES VIA ALTERNATING COPOLYMERIZATION BY DAVID PAUL VANDERBILT A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1982

PAGE 2

To my parents: John and Betty Vanderbilt who made it all possible. To my aunt and uncle: John and Helene Taras who instilled in me an appreciation of chemistry.

PAGE 3

ACKNOWLEDGEMENTS I would like to thank Dr. George B. Butler for the opportunity to work under his tutelage for the past three years. His encouragement and guidance is sincerely appreciated. I also thank the members of my supervisory committee. Special thanks are extended to Dr. Kurt G. Olson, Dr. Huey Pledger, Jr., Dr. Roy King and Dr. Thomas Baugh for invaluable advice and assistance. I also thank Ms. Patty Hickerson for the skillful typing of this manuscript. I am especially indebted to my friends outside of chemistry for keeping me sane. Financial support for this work from the National Science Foundation (Grant DMR 80-20206) is gratefully acknowledged. in

PAGE 4

TABLE OF CONTENTS PAGE ACKNOWLEDGEMENTS iii LIST OF TABLES vi LIST OF FIGURES vi i ABSTRACT ix CHAPTER I. INTRODUCTION 1 Kinetic Scheme for Esterolysis 1 Effective Binding 2 Chemistry at the Active Site -Cooperativity 4 Choice of Catalytic Functional Groups 7 Proposal of Research 9 II. EXPERIMENTAL 12 General 12 Solvents 13 Reagents 14 Maleimide and Maleamic Acid Synthesis 14 Succinimides and Succinamic Acids 25 Vinyl Ethers 28 Imidazole and Histamine Derivatives 31 Other Monomers 40 Homopolymers 42 Copolymers 46 Miscellaneous Reactions 54 Kinetic Measurements 56 III. RESULTS AND DISCUSSION 60 Imidazole -Maleimides 62 Hydroxamic Acid -Maleimides 64 Carboxylic Acid -Maleimides 67 Imidazole -Vinyl Ethers 69 Other Imidazole Monomers 71 TV

PAGE 5

PAGE Copolymerization of Maleimides with N-( 8-Vinyloxyethyl )imidazole (28) 75 Copolymerization of Fumaronitrile (45) and Diethyl fumarate (44) With N-(B-Vinyloxyethyl imidazole (28) ... 88 Copolymerization of Maleimide (_16) With B-Vinyloxyethyl(imidazol-4ylmethyl )piperidinium Chloride (30) 90 Copolymerization of Maleimide (_U) with 4-Allyl imidazole (38) 93 Homopolymers 93 Copolymerization of Propenyl phenols With Maleic Anhydride (47) and N-Ethylmaleimide (43) 98 Kinetic Studies With Imidazole, 50, and 53 102 Kinetic Studies With Copolymers 59, 60, 62, 63 and 68 and Model Compound 26 104 Conclusion 112 APPENDIX: SELECTED l H AND 13 C NMR SPECTRA 114 REFERENCES 131 BIOGRAPHICAL SKETCH 136

PAGE 6

LIST OF TABLES TABLE PAGE I Functional Groups Involved in the Catalytic Action of Some Hydrolytic Enzymes 8 II Hydrogenation of 4-Nitroimidazole (39) 63 III Acylation of Histamine (20) with V0C-C1 73 IV Solubility of 53 in Salt Solutions 84 V Copolymerization of B-Vinyloxyethyl (imidazol-4ylmethyl )piperidinium Chloride (30) 92 VI Copolymerization of 4-Allylimidazole (38) 94 VII Homopolymerization of N-(6-Vinyloxyethyl )imidazole (28) . 97 VIII Properties of Copolymers _57 > 64 102 IX Esterolysis of PNPA with Imidazole, 50, and 53 103 X Esterolysis of DNPB with 26, 59, 60, 62, 63 and 68. . . . 105 VI

PAGE 7

LIST OF FIGURES FIGURE 13, acetone-d. PAGE 1 Proton decoupled C NMR spectrum of copolymer S3 in D 2 0-HC1, 70°C 80 13 2 Off-resonance decoupled C NMR spectrum of copolymer _53 in D 2 0-HC1, 60°C 82 13 3 Proton decoupled C NMR spectrum of copolymer 5_4 in DpO-HCl, 80°C 89 13 4 Proton decoupled C NMR spectrum of copolymer 50 in 96 5 pH-rate profile for the esterolysis of DNPB using 59 Q , 60 A , and 62 Das catalysts 107 6 Plot of Hsp/C vs. C for copolymer 62_, 0.02M Tris buffer, u = 0.02 (KC1), pH = 9.5 110 7 pH-rate profile for the esterolysis of DNPB using 26 Q and 68 A as catalysts Ill 8 H NMR spectrum of N-(3-Vinyloxyethyl )imidazole ( 28 ) in CDC1 3 114 9 H NMR spectrum of N-(3-Vinyloxyethyl )piperidine (29) in CDC1 3 115 10 H NMR spectrum of 3-Vinyloxyethyl (imidazol-4ylmethyl )piperidinium Chloride (30) in D„0 116 11 H NMR spectrum of N-[(Ethenyloxy)carbonyl]-lH-imidazol-4-ethanamine (35) in CDC1 3 117 12 *H NMR spectrum of 4-Allylimidazole (38) in CDC1 3 118 1 13 13 H decoupled C NMR spectrum of Poly(N-Acetoxymaleimide) (48) in CDgCMCHClJ.at 60°C 119 14 H decoupled 3 C NMR spectrum of Poly(Phenyl N-Maleimidyl Carbonate) (49) in CD 3 CN at 70°C 120 vn

PAGE 8

FIGURE 15 16 17 18 19 20 21 22 23 24 PAGE 13 H decoupled C NMR spectrum of Poly[N-(4-Carbethoxyphenyl )maleimide] (51) in acetone-d, at 50°C 121 — b H NMR spectrum of N-(3-Vinyloxyethyl )imidazole-NHydroxymaleimide alternating copolymer (53) in DMS0d 5 at 120°C 122 13 H decoupled C NMR spectrum of N-(g-Vinyloxyethyl )imidazole-Di ethyl fumarate copolymer (56) in CDC1 ? . . . 123 13 H decoupled C NMR spectrum of Isoeugenol — Maleic Anhydride copolymer (5_7) in acetone-d g at 45°C 124 13 H decoupled C NMR spectrum of 2-Propenyl phenol -Maleic Anhydride copolymer (58) in DMSO-dg at 120°C . . 125 13 H decoupled C NMR spectrum of Isoeugenol -N-[2(4Imidazolyl )ethyl] maleimide copolymer (59) in DMSO-d,at 110°C ? . 126 13 H decoupled C NMR spectrum of trans-Anethole -Maleic Anhydride copolymer (61) in DMSO-dg at 110°C 127 13 H decoupled C NMR spectrum of Isoeugenol --N-Ethylmaleimide copolymer (63) in DMSO-dg at 110°C 128 13 H decoupled C NMR spectrum of 2-Propenyl phenol -NEthylmaleimide copolymer (64) in DMS0-d g at 110°C ... 129 13 H decoupled C NMR spectrum of N-Acetoxymaleimide cyclotrimer (65) in CD 3 CN at 70°C 130 vm

PAGE 9

Abstract of Dissertation Presented to the Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy BIFUNCTIONAL SYNZYMES VIA ALTERNATING COPOLYMERIZATION By David Paul Vanderbilt December 1982 Chairman: Dr. George B. Butler Major Department: Chemistry The synthesis, characterization and evaluation of bifunctional synthetic enzymes (synzymes) via alternating copolymerization was carried out. It was desired to obtain copolymers containing alternating placements of complementary functional groups to see if "cooperativity" between the groups (in the hydrolysis of ester substrates) could be greater than in a random copolymer containing the same groups. To this end, the following bifunctional alternating copolymers were synthesized: N-(3-vinyloxyethyl )imidazole -N-hydroxymaleimide (53.), isoeugenol -N-[2-(4-imidazolyl)ethyl] maleimide (59), and 2propenyl phenol -N-[2-(4-imidazolyl )ethyl] maleimide (60). These copolymers were evaluated as catalysts in the hydrolysis of p-nitrophenyl acetate (PNPA) or 2,4-dinitrophenyl benzoate (DNPB). No cooperativity between imidazole and hydroxamic acid or imidazole and phenol groups was observed in the hydrolysis of activated esters, leaving unresolved ix

PAGE 10

the premise that bifunctional alternating copolymers should make better catalysts than bifunctional random copolymers.

PAGE 11

CHAPTER I INTRODUCTION A great deal of attention has been given to the understanding of the catalytic properties of enzymes. Enzymes are globular proteins (polyamino acids) which catalyze most of the chemical reactions in living organisms. Recently, we have begun to understand the mechanisms by which enzymes catalyze organic reactions in terms of the transition state theory. As man's knowledge of enzyme mechanism has grown, so too has his wish to synthesize artificial enzymes or "synzymes." Synzymes have shown considerable utility as probes of enzyme 2 kinetics. These synthetic enzymes should emulate the desirable characteristics of natural enzymes, i.e., show high selectivity and high efficiency (rate enhancement) toward the substrate molecule. To date, both characteristics have been incorporated into synthetic polymers to some degree. As this work deals with the synthesis and evaluation of synzymes, a brief discussion of recent developments in the field follows. Kinetic Scheme for Esterolysis Enzymes are capable of catalyzing a great variety of chemical reactions; one of the most studied of these is the esterolysis (ester hydrolysis) reaction. In general, the kinetic scheme for the hydrolysis of an activated ester by a catalyst can be represented as follows:

PAGE 12

Cat + RC0 2 R' k -i ' k ' III a Cat -RC0 2 R' k II a Cat-CR + OR II IV *Cat + RC0 2 H H 2 where Cat is the catalyst, and RC0 ? R' is the ester substrate. Step I represents an equilibrium between free catalyst and free substrate and a catalyst-substrate complex or Michael is complex. This step is assumed to be rapid and reversible with non-covalent binding forces holding the complex together. The actual hydrolysis steps then take place via acylation of the catalyst (II) and subsequent deacylation (IV). This pathway is believed to be important in the case where the catalyst is a natural enzyme. Alternatively, acylation of the catalyst may occur via a bimolecular reaction (III), in which no preassociation of catalyst and substrate has taken place. This pathway is followed in the case of small molecule catalysts and many synzymes. Catalysis by a synzyme might follow both reaction pathways simultaneously. Effective Binding Effective binding between catalyst and substrate prior to the acylation step plays a key role in providing high catalytic activity. This pre-association step greatly increases the esterolysis rate by increasing the concentration of substrate at the active site of the

PAGE 13

catalyst. Furthermore, acylation can take place via an intramolecular reaction (II) rather than by the much slower intermolecular pathway (III). At least four types of binding forces have been identified in the pre-association process: coulombic interactions, hydrophobic interactions, hydrogen bond formation, and charge-transfer interactions. The most important factor determining the catalyst's effectiveness, however, is that the binding take place at a site which is favorable for the subsequent acylation reaction to occur. An example of coulombic interactions as the mode of polymer-substrate binding has been demonstrated by Overberger and flaki. 3 Poly[4 (5)-vinylimidazole-co-acrylic acid] (1 ) , containing an excess of acrylic acid units (53.7 mol%) and therefore having an excess of anionic sites, hydrolyzed positively-charged 3-acetoxy-N-trimethylanilinium iodide (ANTI) faster than neutral p-nitrophenyl acetate (PNPA), which in turn was hydrolyzed faster than the negativelycharged substrate 3-nitro-4-acetoxybenzoic acid (NABA). N(CH 3 ) 3 I PNPA ANTI II COH ^fl 3 N0 2 NABA

PAGE 14

This study also demonstrates a certain degree of selectivity shown by the catalyst toward the substrate. Favorable binding by hydrophobic interactions has been demonstrated by Klotz and Stryker. a They found that partially lauroylated poly(ethylenimine) catalyzed the hydrolysis of PNPA at a faster rate than did poly(ethylenimine) itself. Indeed, the most effective synzyme studied to date is a dodecylated poly(ethylenimine) containing imidazole residues. This derivative was found to approach a-chymotrypsin in 4b S catalytic activity. On the other hand, Overberger and Smith studied the effect of varying the chain length of substrate (2) using poly(lbutyl-5-vinylimidazole) (3_) and poly(l-methyl-5-vinylimidazole) (4) as catalysts. CH 3 (CH 2 ) n C0 2 ^QK0 2 H /=4 2 N 2 n = 0, 5, 10, 16 It was found for both (_3) and (_4) that (2, n = 16) was hydrolyzed at a faster rate than {2, n = 0). Chemistry at the Active Site--Cooperativity As we have seen above, in order to observe a significant rate enhancement in esterolysis reactions the substrate must first be bound to the polymer near or at the active site. Only after complexation has occurred do the actual hydrolysis steps take place. Synzyme esterolysis has been observed to proceed with or without a complexation step. Studies with a-chymotrypsin (a serine proteinase consisting of 245 amino acid residues) have shown that a serine 0~ anion is responsible for catalytic acylation of substrate.

PAGE 15

H-N N...H-0 0-H....N N-H X=l ~0-(Ser 195) Asp(102) His(57) Ser(195) The serine hydroxyl group is activated for the acylation reaction by the scheme shown above, dubbed a "charge relay system," in which the imidazole moiety plays an integral role in lowering the activation energy for catalysis. A variety of cooperative effects among the functional groups responsible for catalytic action is common in natural enzymes. The synthetic chemist has also sought to take advantage of cooperativity in order to produce more efficient synzymes. A good example of Afunctional cooperation utilizing a molecular relay system was demonstrated by Kunitake and Okahata. These workers found that the rate of hydrolysis of PNPA was 1000 times faster using a terpolymer N-phenylacrylohydroxamate : 4(5) -vinyl imidazole : acryl amide (_5) compared with N-phenylacrylohydroxamate : acrylamide copolymer (6) as catalysts. ?\/ \)H A Ph OH

PAGE 16

The acylation step was demonstrated to occur primarily via the hydroxamate anion, which is known to be a highly nucleophilic species. It is also known that decomposition of an acyl hydroxamate is a slow process; the fact that _5_ is a much better catalyst than 6 implies that imidazole is catalyzing deacylation of the acyl hydroxamate intermediate either acting as a nucleophile or general base. Another example of a Afunctional catalyst exhibiting cooperativity is a 1:1.95 copolymer of 4(5)-vinylimidazole and p-vinylphenol (_7). This copolymer was 63 times as efficient as imidazole for the hydrolysis of ANTI at pH 9.1, and 10.6 times as effective as imidazole vs. PNPA at the same pH. Phenol, poly(p-vinylphenol ) , poly[4(5)vinylimidazole] and a 1:0.48 copolymer of 4(5)-vinylimidazole and pmethoxystyrene gave no significant rate enhancement under the same conditions. "" '1.95 o OH 7 This great rate enhancement was attributed to cooperativity between imidazole and phenolate ion, which might involve (i) phenol anion acting as a general base assisting the decomposition of the tetrahedral intermediate and/or (ii) the phenol anion activating a neutral imidazole for nucleophilic attack on the substrate. Cooperative interactions have been demonstrated in small molecules by Bender etal. 7b

PAGE 17

W N-C-.O-H OR CH H-N X N *C=0 OR i ii Polymer Configuration Catalytic properties of polymers are influenced to a large extent by the configuration (conformation) of the polymer in solution. Vinyl polymers are rather flexible as compared with enzymes, i.e., they usually lack specific secondary and unique tertiary structure. As a result, synthetic polymers lack the specific binding pocket which is typical of enzymes. Therefore, the catalytic efficiency of synzymes will depend to a large extent on the pH, ionic strength and composition of the medium, distance of the catalytic group from the polymer backbone, degree of dissociation of catalytic groups, and many other considerations. Choice of Catalytic Functional Groups As we have seen above, combinations of cooperative and/or complementary functional groups are necessary to achieve high catalytic efficiency. Catalysis by hydrolytic enzymes is of the nucleophilic and acid-base type. Table I contains a list of functional groups which are directly involved in the catalytic action of some hydrolytic enzymes.

PAGE 18

TABLE I "oups In Catalytic Action of Some Hydrolytic Enzymes Functional Groups Involved in the 9 _ Enzyme Functional Group Serine protease Chymotrypsin Trypsin -OH(Ser), >» — N (His), -C00H (Asp) a-Lytic protease Elastase Subtilisin Papain -SH(Cys), >, — n (His) Ribonuclease V-N y« NH (HiSj protonated ) (H,sK o H H Lysozyme -C00H (Glu), -COO" (Asp) Carboxypeptidase /^v 2+ D)~ 0H (T ^ r) ' Zn '

PAGE 19

Proposal of Research As was stated previously, synthetic vinyl macromolecules containing bior multi-functionalities have been studied in other laboratories and have shown enzyme-like catalytic activity. These studies have shown a cooperativity between the functionalities leading to a rate enhancement for esterolysis reactions. However, up to this time, functionalities have been introduced into copolymers in random fashion. This ensures a degree of cooperation between the functionalities which is dependent on the degree of alternation (i) or upon the conformation of the polymer chain (ii) as depicted below. '©' © YD It appeared to us that the degree of cooperativity between functional groups could be maximized by preparing regular alternating copolymers. This would assure that each functional group of a given type would be flanked on either side by a functional group of the complementary type.

PAGE 20

10 Fundamental to this proposed research is the selection of monomer pairs which undergo regular alternating copolymerization under freeradical conditions. This type of copolymerization is generally thought to result from the formation of a 1:1 charge-transfer complex between electron-rich (donor) and electron-deficient (acceptor) monomer pairs. Some examples of monomer pairs which give regularly alternating coo polymers include styrene -N-phenylmaleimide, 2-chloroethyl vinyl 9 10 ether -maleic anhydride, styrene -maleic anhydride, 2-allyl phenol -maleic anhydride, and 2-allylphenol -N-phenylmaleimide. In these laboratories, the alternating copolymerization of N-phenylmaleimide and 2-chloroethylvinyl ether has been studied extensively k m 12 by Olson. It was concluded in this study that the predominant propagation mechanism is homopolymerization of a 1:1 donor-acceptor complex. An excellent review of the role of the charge-transfer complex in alter12 nating copolymerization can be found in this work. Our goal of producing Afunctional synzymes via alternating copolymerization could be approached by at least two methods. The first method, which we believed would result in fully functional ized copolymer, is the direct polymerization of monomer pairs containing the

PAGE 21

11 desired functional groups (or the desired functional groups in masked or protected forms) . A A B The second method involves derivatization of a pre-existing alternating copolymer. This method suffers from the fact that polymers can be difficult to functional ize completely and resultant difficulties associated with characterization of a partially functionalized polymer. We have approached the problem via both methods. Our initial efforts were aimed at direct polymerization of appropriately substituted monomer pairs. Difficulty was encountered effecting copolymeri zation due to side reactions caused by one of the unprotected functionalities. Hence, derivatization of a pre-existing alternating copolymer was also attempted.

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CHAPTER II EXPERIMENTAL General Melting points were determined on a Thomas-Hoover Capillary Melting Point Apparatus or a Fisher-Johns Melting Point Apparatus and are given in degrees Celsius (uncorrected). Pressures are expressed in millimeters (mm) of mercury. Elemental analyses were performed by Atlantic Microlabs, Inc., Atlanta, Georgia, and Schwarzkopf Microanalytical Laboratories, Inc., Woodside, New York. Proton nuclear magnetic resonance (NMR) spectra (60 MHz) were recorded on Varian A-60A or Jeol JNM-PMX-60 instruments. Carbon-13 NMR (25 MHz) and 100 MHz proton NMR spectra were recorded on a JeolJNM-FX-100 spectrometer. Chemical shifts are expressed in parts per million (ppm) on the 6 scale downfield from tetramethylsilane (TMS) or sodium 2,2-dimethyl-2-silapentane-5-sulfonate (DSS) unless otherwise indicated. In cases where no internal reference was added, spectra were calibrated via a characteristic signal of the deuterated 13 solvent used. The solvent used and calibration information are given in parentheses for each spectrum reported. Multiplicities of proton and off-resonance decoupled carbon resonances are designated as singlet (s), doublet (d), triplet (t), quartet (q), multiplet (m), or broad (br) . 12

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13 Infrared (IR) spectra were recorded on a Perkin-Elmer 281 spectrophotometer. Absorbances are expressed in wavenumbers (cm" ) using polystyrene (1601 cm" ) calibration. Solid samples were run as a KBr pellet; liquid samples were analyzed neat as a thin film between NaCl plates. Absorption bands are assigned the classifications: weak (w), medium (m), strong (s), very strong (vs), broad (br), and shoulder (sh) Low resolution mass spectra (LRMS) and high resolution mass spectra (HRMS) were recorded on an Associated Electronic Industries (AEI) Model MS-30 spectrometer. Number average molecular weights (M ) of polymers were determined by vapor pressure osmometry (VPO) on a Wescan 233 Molecular Weight Apparatus. Benzil was used as a calibration standard. Intrinsic viscosities were measured with a Ubbelohde viscometer (dilution viscometer). Gel Permeation Chromatography (GPC) of polymers was carried out on a Waters Associates Liquid Chromatograph using glycerated porous glass columns and both ultraviolet (UV) and differential refractometer detectors. Compound headings appear with the common name(s) listed first, followed by the systematic name as found in Chemical Abstracts (CA). CA registry numbers of known compounds are given in brackets. Solvents Deuterated NMR solvents were obtained from the Aldrich Chemical Co. and Merck and Co., Inc. All solvents used for general applications were of Reagent grade or ACS grade quality. For special applications, solvents were distilled. Reference to a distilled solvent

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14 in this chapter indicates that the solvent was purified in the manner 14 described below. Methanol was distilled from Mg(0CH 3 ) 2 . Tetrahydrofuran (THF) was distilled from CahL. Dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) were allowed to stand over KOH and were distilled from CaO. Dioxane was refluxed with aqueous HC1 , dried over KOH and distilled from sodium metal. Ethanol-free chloroform (CHC1-) was obtained by extraction of reagent grade CHClg with cone. FLSO, and water, followed by distillation from P^Aq. Dichloromethane (ClLCl-) was distilled from P^q. Acetone was distilled from Nal. Reagents Starting materials and reagents were obtained from the following suppliers: Aldrich Chemical Co., Fisher Scientific Co., Mallinckrodt, Inc., Eastman Kodak Co., and Polysciences, Inc. Maleimide and Maleamic Acid Synthesis 3,6-Endoxo-l,2,3,6-tetrahydrophthalic Anhydride/3a,4,7,7a-Tetrahydro4,7-epoxyisobenzofuran-l,3-dione [5426-0905] (8) The following procedure was modified from the procedure of Narita 15 et al. To a 1 L three-necked round-bottomed flask equipped with a mechanical stirrer and reflux condenser was added 109.2 g (1.604 mol) of freshly distilled furan and 200 mL of benzene. The solution was cooled via an external ice bath to 0-5°C, after which 157.3 g (1.604 mol) of maleic anhydride was added portionwise. The ice bath was removed after refluxing had slowed, and the mixture was stirred at room temperature for 24 h. Additional benzene was added to facilitate stirring. The mixture was filtered and dried in vacuo to give 235.9 g (88.5%) of white crystalline product (8), mp 115-116°C (dec) [literature mp 118°C (dec)]. 16

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15 X H NMR (DMS0-d 6 , TMS): 3.32 (s, 2H), 5.35 (s, 2H), 6.57 (s, 2H). 13 C NMR (DMSO-d 5 , 39.5): 49.10, 81.75, 136.90, 171.53. IR (KBr): 3195 (w), 3162 (w), 3136 (w), 3102 (w), 2995 (w), 1860 (s), 1787 (vs, br), 1640 (w), 1595 (w), 1567 (w), 1380 (w), 1321 (m, sh), 1310 (m) , 1282 (m), 1242 (m, sh), 1230 (s), 1218 (s), 1193 (m), 1145 (m), 1086 (s), 1020 (s), 1000 (m), 950 (s), 920 (s), 903 (s), 878 (s), 848 (s), 820 (m), 798 (m) , 731 (m), 689 (m), 672 (m), 633 (m), 620 (w). N-Hydroxy-3,6-epoxy-l,2,3,6-tetrahydrophthalimide/3a,4,7,7a-Tetrah,ydro-2-hydroxy-4,7-epoxy-lH-isoindole-l,3(2H)-dione L5596-17-8J M 15 The following procedure was obtained from Narita et al . To a 1 L round-bottomed flask equipped with a mechanical stirrer and a 250 mL addition funnel was added 75.3 g (1.083 mol ) of hydroxylamine hydrochloride (dried in a vacuum oven at 60°C overnight) and 400 mL of freshly distilled methanol. After dissolution, the flask was cooled to 0-5°C. The addition funnel was charged with a solution of 60.8 g (1.083 mol) of potassium hydroxide in 150 mL of freshly distilled methanol and the solution added dropwise with vigorous stirring. After addition, the mixture was stirred an additional 0.5 h, and subsequently suction-filtered into a second 1 L three-necked round-bottomed flask fitted with a mechanical stirrer and reflux condenser. To the stirring hydroxylamine solution was added portionwise 180 g (1.083 mol) of 3,6-endoxo-l,2,3,6-tetrahydrophthalic anhydride (8). The mixture was refluxed for 8 h and then allowed to stir for 13 h at room temperature. The flask was cooled in an ice bath, and

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16 the precipitate was filtered and dried in vacuo to yield 128.6 g (65.5%) of white solid (9), mp 189-195°C (dec) [literature mp 187188°C (dec)]. 15 l H NMR (DMS0-d 6 , TMS): 2.86 (s, 2H), 5.13 (s, 2H), 6.53 (s, 2H). 13 C NMR (DMS0-d 6 , 39.5): 43.91, 80.00, 136.24, 172.50. IR (KBr): 3300 (s, br), 3095 (w), 3085 (w), 3050 (w), 3022 (m), 2998 (m), 1787 (s), 1730 (vs, br) , 1567 (w), 1437 (s), 1338 (w), 1305 (m), 1283 (m), 1264 (m) , 1240 (s), 1227 (m, sh), 1207 (m), 1196 (m), 1150 (s), 1089 (s), 1070 (m), 1010 (m), 951 (m) , 916 (m), 881 (s), 846 (m), 823 (m), 803 (m), 792 (m), 720 (s), 644 (s). N-Acetoxy-3,6-epoxy-l,2,3,6-tetrahydrophthalimide/2-(Acetyloxy)-3a, 4,7,7a-tetrah.ydro-4,7-epox,y-lH-isoindole-l,3(2H)-dione [3246366-4J (10) To a 250 mL three-necked round-bottomed flask fitted with a mechanical stirrer and reflux condenser was added 47.7 g (0.263 mol ) of 9_ and 135 mL of acetic anhydride. The stirred mixture was heated to 89-90°C via an oil bath and maintained at this temperature for 3 h. The resulting solution was cooled to room temperature and placed in a refrigerator overnight. The precipitate was filtered and washed with cold benzene. A second crop of crystals was obtained by concentration of the combined mother liquors in vacuo, followed by precipitation into water. The combined products were recrystallized from benzene and dried in vacuo to afford 34.14 g of white crystals. An additional 10.17 g fraction was obtained from concentration of the benzene mother liquor (75.4%), mp 139-143°C (dec) [literature mp 137138°C (dec)]. 15

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17 L H NMR (CDC1 3 , TMS): 2.30 (s, 3H), 2.87 (s, 2H), 5.27 (s, 2H), 6.47 (s, 2H). 13 C NMR (DMS0-d 6 , 39.5): 17.08, 44.03, 79.85, 135.02, 165.46, 169.26. IR (KBr): 3095 (w), 3020 (w, sh), 2998 (m) , 1810 (s), 1783 (s), 1735 (s), 1430 (w), 1375 (s), 1350 (m), 1284 (m) , 1272 (m) , 1230 (s), 1218 (s, sh), 1192 (s), 1168 (s), 1139 (s), 1092 (s), 1060 (s), 1012 (m), 992 (m), 985 (m), 915 (m), 878 (s), 845 (m, sh), 836 (m), 817 (m), 800 (s), 739 (m), 710 (m), 693 (m), 637 (m), 629 (m) N-Acetoxymalei mi de/l-( Acetyl oxy)-lH-pyrrole-2,5-di one (11) To a 100 mL one-necked round-bottomed flask was added 49.47 g of 10 and a Telfon-coated stir bar. A short path vacuum distillation head was fitted to the flask, and the pressure of the system was reduced to 25 mm. The flask was heated slowly to approximately 180°C. Decomposition of the solid occurred before 140°C and was accompanied by the evolution of furan. The product was then distilled, bp 140146°C (24 mm Hg), and collected by cooling the receiving flask. Two recrystallizations from CC1. gave 28.36 g (82.5%) of white crystalline product Ul), mp 70.5-71.5°C (literature mp 70.5-71.5°C) . 15 l H NMR (CDC1 3 , TMS): 2.32 (s, 3H), 6.70 (s, 2H). (DMS0-d 6 , TMS): 2.38 (s, 3H), 7.18 (s, 2H). 13 C NMR (CDC1 3 , TMS): 17.33, 132.44, 164.22, 166.80. (DMS0-d 6 , 39.5): 17.03, 133.08, 165.05, 167.49. IR (KBr): 3080 (w), 3057 (m) , 3048 (m) , 3003 (w), 2950 (w), 2880 (w), 1818 (s), 1782 (s), 1740 (vs), 1577 (w), 1432 (w), 1380 (s), 1341 (w), 1317 (w), 1177 (s), 1123 (s), 1048 (s), 1007 (w), 820 (s), 778 (m), 670 (s).

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18 Elemental Analysis: Calcd. for C c H c N0 o : C, 46.46; H, 3.25; N, 9.03. b b J Found: C, 46.49; H, 3.28, N, 9.04. Phenyl N-(3 ,6-Epoxy-l ,2 ,3 ,6-tetrahydrophthal imidyl ) Carbonate/3a ,4 , 7,7a-Tetrahydro-2-[(phenoxycarbonyl )oxy]-4,7-epoxy-lH-isoindolel,3(2H)-dione [60361-88-8] (12) The following procedure was adopted from Akiyama et al . To a 500 mL three-necked round-bottomed flask fitted with a mechanical stirrer and addition funnel was added 76.4 g (0.422 mol ) of 9 and 210 mL of freshly distilled DMF. The flask was cooled to 0-5°C via an external ice bath, and 58.8 mL (0.422 mol) of dry triethylamine was added. The addition funnel was charged with 66.03 g (0.422 mol) of phenyl chloroformate which was added to the stirred solution over a 1 h period. The ice bath was removed and the mixture allowed to stir an additional 3 h. Triethylamine hydrochloride was filtered out and the filtrate precipitated into 2 L of water. Additional product was obtained by dissolving the filtered Et^N-HCl in 1 L of water. Both precipitates were suction filtered and dried in vacuo giving 126.3 g of crude product. Recrystallization from isopropanol afforded 71.4 g (56.3%) of white needles, mp 137-139°C (literature mp 135-136°C) . 17 X H NMR (CDC1 3 , TMS): 2.88 (s, 2H), 5.32 (s, 2H), 6.48 (s, 2H), 7.207.45 (m, 5H). 13 C NMR (CDC1 3 , TMS): 44.25, 80.47, 120.28, 126.96, 129.74, 136.22, 149.97, 150.70, 168.29. IR (KBr): 3095 (w), 3075 (w), 3060 (m) , 3022 (w), 3003 (w), 1817 (s), 1790 (s), 1740 (vs), 1600 (w), 1585 (m), 1485 (m), 1460 (m) , 1360 (m), 1310 (m), 1272 (s), 1230 (vs, br), 1148 (s), 1092 (s), 1068

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19 (s), 1019 (m), 1005 (m, sh), 998 (m), 973 (m) , 954 (m) , 917 (m) , 882 (s), 850 (m), 817 (m), 803 (m), 788 (m) , 774 (m), 753 (m) , 730 (m), 713 (m), 686 (m) , 660 (w), 629 (m), 622 (m). Phenyl N-Maleimidyl Carbonate/l-[(Phenoxycarbony1 )oxy]-lH-pyrrole-2, 5-dione [60361-89-9] (13) " — Into a 250 mL Erlenmeyer flask was placed 38.68 g (0.128 mol ) of 12, 0.428 g (2.57 mmol ) of 4-tert-butyl catechol , 70 mL of bromobenzene, and a few boiling chips. The mixture was heated on a hot plate at such a rate as to allow bromobenzene vapors to condense in the neck of the flask (~160°C inside the flask) for 1.5 h. Bromobenzene was then removed in vacuo and the resulting solid recrystallized from cyclohexane and dried in vacuo giving 24.51 g (81.8%) of maleimide ( 13 ) as a pale-yellow solid, mp 99-102. 5°C (literature mp 98-99°C). 17 A quantity of J_3 was sublimed at 1 mm (100°C) affording white crystals, mp 101-104°C. *H NMR (CDC1 3 , TMS): 6.77 (s, 2H), 7.20-7.45 (m, 5H). 13 C NMR (CDC1 3 , TMS): 120.33, 127.06, 129.84, 132.62, 150.75, 163.47. IR (KBr): 3160 (w), 3100 (m), 3070 (w) , 1818 (s), 1783 (s), 1740 (vs), 1587 (m), 1578 (m) , 1492 (m) , 1482 (m), 1456 (w) , 1375 (m), 1220 (vs), 1162 (m), 1155 (m), 1126 (s), 1050 (m), 1023 (m) , 1004 (m), 974 (m), 910 (w), 860 (w), 815 (s), 778 (w), 765 (m), 752 (m), 743 (in), 715 (m) , 685 (m) , 667 (s), 638 (m). N-Hydroxymaleimide/l-Hydroxy-lH-pyrrole-2, 5-dione [4814-74-8] (14) N-Hydroxymaleimide was prepared via the procedure of Akiyama et al . Thus, to a 100 mL three-necked round-bottomed flask fitted with a reflux condenser and magnetic stir bar was added 7.358 g

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20 (0.0316 mol) of 13 and 40 mL of freshly distilled methanol. The solution was refluxed for 2 h, after which the methanol was removed in vacuo. The residual oil was triturated with a solution of 7:5 hexanes: benzene, and the resulting solid was recrystallized from toluene and dried in vacuo to give 1.55 g (43.4%) of an off-white crystalline solid (.14), mp 126-130°C (literature mp 125-126°C) . 17 Spectral properties were in agreement with those of an authentic sample kindly supplied by Dr. M. Akiyama. *H NMR (acetone-d 5 , TMS): 6.76 (s, 2H), 9.20 (br, 1H). (DMS0-d 6 , TMS): 6.92 (s, 2H), 10.29 (br, 1H). 13 C NMR (acetone-d 6 , TMS): 125.50, 160.05. (DMS0-d 6 , 39.5): 131.91, 167.00. IR (KBr): 3150 (m, br), 3100 (m), 2950 (w), 2850 (w), 1785 (m), 1730 (vs), 1572 (w), 1488 (m), 1306 (w), 1230 (w), 1175 (s), 1130 (m), 1047 (m), 1041 (m), 822 (s), 773 (w), 735 (m), 670 (s). N-(4-Carbethox,yphenyl)maleani1ic Acid/(Z)-4-[(3-Carbox,y-l-oxo-2-propenyl)amino]benzoic acid, 1-ethyl ester L53616-17-4] (15) To a 500 rnL Erlenmeyer flask was added 24.4 g (0.148 mol) of ethyl p-aminobenzoate and 250 mL of chloroform. The stirred solution was cooled in an ice bath, and 14.5 g (0.148 mol) of maleic anhydride was added portionwise. After 1 h, the mixture was warmed to room temperature and stirred overnight. The white precipitate was filtered, washed with CHC1 3 , and dried in vacuo, affording 38.1 g (98%) of maleanilic acid (V5) . A portion of the product was recrystallized from CH 3 CN, mp 190-192°C.

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21 ! H NMR (DMS0-d 6 , 2.49): 1.28 (t, 3H), 4.25 (q, 2H), 6.41 (AB q, 2H), 7.84 (AB q, 4H), 10.62 (s, 1H). 13 C NMR (DMSO-d 6 , 39.5): 14.20, 60.51, 118.89, 124.74, 130.30, 131.71, 143.07, 163.78, 165.34, 166.95. IR (KBr): 3300 (m), 3205 (m), 3110 (m), 2975 (w) , 1710 (s), 1635 (m), 1610 (m), 1580 (s), 1540 (s), 1470 (m) , 1415 (w), 1405 (m), 1365 (m), 1330 (m), 1310 (m), 1270 (s), 1225 (w), 1175 (m), 1120 (m), 1105 (m), 1025 (m), 1010 (w), 970 (m), 900 (w), 865 (m), 850 (m), 770 (m), 695 (w), 680 (w), 610 (m). N-(4-Carbethoxypheny1 )ma1eimide/[4-(2,5-Dihydro-2,5-dioxo-lH-pyrroll-y1)benzoic acid, ethyl ester] [14794-06-1] (16) To a 500 mL one-necked round-bottomed flask was added 38.1 g (0.145 mol) of _15_ , 1.2 g (0.015 mol ) of anhydrous sodium acetate, and 100 mL of acetic anhydride. A magnetic stir bar was added, and a reflux condenser was fitted. The stirring mixture was brought to 90°C over a 1.0 h period, and then allowed to cool to room temperature. The resulting solution was precipitated into 1.5 L of ice-water and allowed to stir overnight. The yellow solid was collected by filtration, recrystallized from ethanol -water, and dried in vacuo, giving 29.57 g (83.4%) of yellow plates, mp 112-113°C (literature mp 113°C). 18 l H NMR (CDC1 3 , TMS): 1.38 (t, 3H), 4.37 (q, 2H), 6.84 (s, 2H), 7.80 (AB q, 4H). 13 C NMR (CDC1 3 , 77.0): 13.94, 60.77, 124.86, 129.00, 129.93, 133.97, 135.10, 165.26, 168.63. IR (KBr): 3470 (w), 3090 (w), 2995 (w), 2900 (w), 1718 (vs), 1710 (vs), 1603 (m), 1507 (m), 1472 (w), 1442 (w), 1405 (m, sh), 1395

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22 (s), 1382 (s), 1365 (m, sh), 1307 (m, sh), 1282 (s), 1213 (w) , 1175 (m), 1142 (m), 1128 (m) , 1108 (m), 1068 (w), 1022 (m) , 948 (w), 853 (m), 830 (m), 764 (in), 699 (m), 684 (m) , 638 (w). N-Hydrox,ymaleamic Acid [4296-73-5] (17) N-Hydroxymaleamic acid Q7) was prepared from the addition of hydroxyl amine [from 61.5 g (0.885 mol ) of hydroxy! amine hydrochloride neutralized with one equivalent of sodium methoxide in methanol] to a solution of 86.8 g (0.885 mol) of maleic anhydride in distilled dioxane at 0°C. After warming to room temperature and stirring for 1 h, the product was filtered and dried in vacuo, affording 69.3 g (60%) of 17, mp 126-129°C (dec) [literature mp 122-128°C (dec)]. 19 ! H NMR (DMS0-d 6 , TMS): 6.30 (s, 2H). 13 C NMR (DMS0-d 5 ; 39.5): 129.22, 132.98, 162.17, 165.93. IR (KBr): 3500-2600 (br, s), 3180 (s), 1695 (m) , 1630 (s), 1540 (br, vs), 1400 (s), 1310 (m), 1230 (br, s), 1080 (m), 1065 (s), 990 (m), 980 (m), 915 (m), 847 (m), 800 (m), 730 (m), 630 (m). N-Carbethoxymaleimide/2,5-Dihydro-2,5-dioxo-lH-pyrrole-l-carbox,y1ic acid, ethyl ester [55750-49-7] (18) ^ ' ' * on This maleimide was prepared by the method of Keller and Rudinger in 44% yield, mp 55-57°C (literature mp 58-59°C). 20 l H NMR (CDC1 3 , TMS): 1.42 (t, 3H), 4.45 (q, 2H), 6.84 (s, 2H). IR (KBr): 3180 (w), 3100 (m) , 2985 (m) , 1795 (s), 1770 (vs), 1710 (m), 1595 (m), 1475 (m), 1445 (m) , 1398 (m), 1370 (m), 1330 (s), 1265 (s), 1130 (m), 1102 (m), 1053 (m) , 1035 (m), 995 (m), 850 (m), 765 (m), 755 (m), 690 (m), 635 (m).

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23 N-[2-(4-Imidazolyl)ethyl]maleamic Acid/(Z)-4-([2-(lH-Imidazo1-4-yl ) ethyl ]amino)-4-oxo-2-butenoic Acid (19) In an Erlenmeyer flask was combined 0.437 g (3.93 mmol ) of histamine (20), 0.367 g (3.74 mmol) of maleic anhydride and 20 mL of chloroform (ethanol-free). The mixture was stirred for 20 h; the solid filtered and dried in vacuo, affording 0.672 g (86%) of _19, which slowly decomposed above 120°C. l H NMR (D 2 0, DSS): 2.95 (m, 2H), 3.52 (m, 2H), 6.13 (AB q, 2H), 7.26 (s, 1H), 8.53 (s, 1H). IR (KBr): 3600-2400 (br, m) , 3230 (w), 3135 (w), 3060 (w), 1655 (m), 1625 (s), 1570 (br, s), 1450 (w), 1430 (w), 1398 (w), 1365 (w), 1313 (w), 1270 (m), 1208 (w), 1185 (m), 1100 (br, m), 1065 (w), 975 (m), 902 (w), 855 (br, m), 815 (m) , 730 (w), 715 (m), 638 (m), 610 (m). N-(2-Thiazoly1 )maleamic Acid/(Z)-4-0xo-4-(2-thiazolylamino)-2-butenoic Acid [19789-91-4] (21) ~ ~" Into an Erlenmeyer flask was placed 0.922 g (9.21 mmol) of 2aminothiazole (recrystallized from cyclohexane) , 0.902 g (9.20 mmol) of maleic anhydride and 40 mL of acetone. The mixture was stirred for 45 h at room temperature. The solid was filtered, washed with acetone and dried in vacuo, affording 1.308 g (72%) of yellow powder (21), mp 151-153°C (dec). : H NMR (DMS0-d 6 , 2.49): 6.46 (s, 2H), 7.37 (AB q, 2H). 13 C NMR (DMS0-d 6 , 39.5): 113.97, 128.20, 132.54, 137.90, 157.64, 162.56, 167.14.

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24 IR (KBr): 3090 (w), 3000-2200 (br, m), 1655 (m) , 1618 (m), 1565 (br, s), 1435 (m), 1398 (m) , 1322 (m) , 1270 (s), 1205 (m), 1172 (m), 1060 (m), 905 (m), 850 (m), 775 (m) , 725 (m), 705 (m), 650 (m), 620 (m). N-(4-Carboxyphenyl)maleanilic Acid/4-[(3-Carbox.y-l-oxo-2-propenyl ) amino]benzoic Acid [36847-92-4] (22) 21 This compound was previously synthesized in these laboratories from p-aminobenzoic acid and maleic anhydride, mp 234°C (dec). l H NMR (DMS0-d 6 , TMS): 6.19 (AB q, 2H), 7.72 (AB q, 4H), 10.48 (br, 1H) IR (KBr): 3350-2010 (br, m), 3310 (m) , 3210 (w), 3000 (w), 2840 (br, w), 2665 (w), 2540 (w), 2240 (w), 1705 (s), 1690 (s), 1625 (m), 1580 (s), 1540 (vs), 1420 (m), 1405 (m), 1325 (m), 1310 (m), 1290 (s), 1265 (m), 1220 (w), 1175 (m) , 1120 (w), 1012 (w), 970 (m), 940 (w), 900 (w), 860 (m), 845 (m) , 770 (m), 690 (m), 670 (m), 608 (m). 4-[(3-Carboxy-l-oxo-2-propenyl )amino]benzeneacetic Acid (23) 21 This compound was previously synthesized in these laboratories from p-aminophenyl acetic acid and maleic anhydride, and was used without further purification. l H NMR (DMS0-d 6 , TMS): 3.57 (s, 2H), 6.41 (AB q, 2H), 7.41 (AB q, 4H), 10.43 (br, 1H). IR (KBr): 3280 (s), 3190 (w) , 3050 (m), 2720 (w), 2620 (w), 2390 (w) , 2240 (w), 1715 (s), 1685 (s), 1615 (s), 1570 (s), 1535 (vs), 1510 (s), 1425 (m), 1400 (m), 1320 (m) , 1300 (m) , 1265 (m) , 1220 (m), 1200 (w), 1180 (m), 1050 (m), 980 (m) , 925 (m), 900 (m), 860 (m), 840 (m), 812 (m) , 790 (m), 775 (m), 720 (m), 670 (w), 630 (m), 610 (m).

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25 N-[2-(4-Imidazolyl)ethyl]-3,6-endoxo-l,2,3,6-tetrahydrophthalic Acid (24) To a 50 mL Erlenmeyer flask was added 2.505 g (0.0136 mol ) of histamine di hydrochloride and 15 mL of water. To the stirred solution was carefully added 2.286 g (0.0272 mol) of NaHCO.,. Into another flask was placed 2.263 g (0.0136 mol) of 8 and 22 mL of acetone. The solution of free-base (20) in water was slowly added to the acetone solution with rapid stirring. Addition of additional acetone (200 mL) was necessary to make the flask contents homogeneous. After stirring 1 h, the liquid phase was decanted off, and the remaining oily precipitate stirred over fresh acetone. The resulting fine white solid was collected and dried in vacuo to give 4.898 g of 24, apparently contaminated by NaCl . The solid gradually decomposed upon heating to 135°C. *H NMR (D 2 0, DSS): 2.73 (s, 2H), 2.67-3.63 (m, 4H), 5.07 (d, 2H), 6.43 (m, 2H), 7.12 (m, 1H), 8.48 (d, 1H). IR (KBr): 3660-2730 (m, br), 3240 (m), 3120 (m), 1715 (w), 1650 (s), 1625 (s), 1555 (s), 1430 (m), 1395 (s), 1310 (w), 1270 (m), 1245 (w), 1218 (m), 1183 (w) , 1167 (w), 1092 (w), 1060 (w), 1028 (w), 1000 (w), 982 (w), 972 (w), 930 (w), 900 (m) , 838 (m) , 820 (m) , 808 (w), 752 (w), 730 (m) , 702 (m), 627 (m). Succinimides and Succinamic Acids N-[2-(4-Imidazol.yl )ethyl]succinamic Acid/4-([2-(lH-Imidazo1-4-yl ) ethyl]amino)-4-oxo-2-butanoic Acid (25) To an Erlenmeyer flask containing a solution of 0.248 g (2.48 mmol ) of succinic anhydride in 5 mL of acetone was added dropwise a

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26 solution of 0.275 g (2.47 mmol ) of histamine in 3.5 mL of water, and the solution was stirred overnight. Absolute ethanol and acetone were added, and the precipitate was collected and dried in vacuo, giving 0.239 g (45.8%) of white solid, mp 159-159. 5°C. l H NMR (DMS0-d 6 , 2.49): 2.37 (m, 4H), 2.63 (m, 2H), 3.26 (m, 2H), 6.84 (s, 1H), 7.68 (s, 1H), 7.98 (t, 1H). 13 C NMR (DMS0-d 6 , 39.5): 26.68, 29.75, 30.44, 38.87, 117.19, 134.00, 134.73, 171.34, 174.41. IR (KBr): 3240 (w) , 3155 (m), 3100 (m), 3000 (m), 2940 (m), 2855 (m) , 1635 (vs), 1610 (s), 1570 (s), 1450 (w), 1420 (s), 1352 (s), 1285 (w), 1205 (s), 1140 (m), 1110 (m) , 1065 (w), 1035 (w), 975 (w), 940 (w), 905 (w), 865 (m) , 820 (m, br), 770 (m), 720 (m) , 640 (m). N-[2-(4-Imidazoly1)ethyl]succinimide/l-[2-(lH-Imidazol-4-yl)ethyl]2,5-pyrrolidinedione (26) A 25 mL three-necked round-bottomed flask fitted with a stir bar, condenser, and gas inlet tube was assembled hot and was cooled by flushing the apparatus with Ar. To the cool flask was introduced 0.734 g (7.34 mmol) of succinic anhydride and 2 mL of distilled DMF. To the stirred solution was added via syringe a solution of 0.820 g (7.38 mmol) of histamine ( 20 ) in 3 mL of DMF. A white solid formed which dissolved when the mixture was heated. The solution was refluxed for 2.5 h and allowed to cool. DMF was removed in vacuo, leaving a brown solid which was recrystallized from CHC1-, mp 164-165°C. *H NMR (DMS0-d 6 , 2.49): 2.58 (s, 4H), 2.67 (m, 2H), 3.56 (m, 2H), 6.83 (s, 1H), 7.57 (s, 1H), 8.87 (br, 1H).

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27 13 C NMR (DMSO-d 6 , 39.5): 24.83, 28.00, 38.04, 116.36, 133.86, 134.88, 177.57. IR (KBr): 3440 (w), 3120 (w), 3080 (w), 3035 (w) , 2990 (w), 2940 (2), 2830 (m), 2750 (w), 2640 (m), 1765 (m) , 1690 (vs), 1575 (m), 1485 (m), 1450 (m), 1438 (m), 1433 (m), 1405 (s), 1330 (s), 1318 (m), 1289 (m), 1260 (w), 1248 (s), 1230 (m), 1150 (s), 1090 (m), 1055 (m), 1030 (w), 1000 (sh, m), 990 (m) , 950 (m), 910 (br, m) , 840 (m), 825 (m), 798 (m), 772 (m) , 660 (m), 630 (m), 608 (w). N-Acetoxysuccinimide [14464-29-0] (27) To a dry 250 mL three-necked round-bottomed flask fitted with a mechanical stirrer, N^ inlet tube and septum cap was added 3.0 g (0.026 mol) of N-hydroxysuccinimide, 100 mL of anhydrous ether, and 20 mL of distilled THF. Dry pyridine (2.06 g, 0.026 mol) was added under N 2 , and the flask was cooled to 0-5°C. To the stirred solution was added dropwise via syringe 1.5 mL (0.0265 mol) of acetyl chloride. The mixture was stirred for 0.5 h at 0° and then at room temperature for 1 h. The flask contents were transferred to a separatory funnel and extracted with 1 N HC1 . The organic layer was dried over anhydrous MgSO., the solvent removed in vacuo, and the residue triturated with hexanes to give white solid. The solid was recrystallized from benzene-hexanes, filtered, and dried in vacuo to afford 1.496 g (36%) of needles (27), mp 131-133. 5°C (literature mp 132-133°C) . 22 *H NMR (CDC1 3 , TMS): 2.33 (s, 3H), 2.82 (s, 2H). 13 C NMR (CDC1 3 , TMS): 17.50, 25.59, 165.71, 169.41. IR (KBr): 2990 (w) , 2940 (w), 1822 (s), 1795 (s), 1745 (vs), 1430 (m), 1380 (s), 1360 (sh, m), 1298 (w), 1255 (m) , 1220 (s), 1170

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28 (s), 1160 (sh, s), 1075 (sh, m), 1060 (s), 1045 (in), 1005 (w), 990 (w), 832 (s), 810 (m), 765 (m), 650 (m). Vinyl Ethers N-(B-Vinyloxyeth,yl)imidazole/l-[2-(Ethenylox,y)ethyl] -1H -imidazole (28) The general procedure for N-alkylation of imidazole described by 23 Fournari et al . was used. To a nitrogen-flushed 500 mL three-necked round-bottomed flask fitted with a mechanical stirrer, condenser, and addition funnel was added 100 mL of freshly distilled THF and 13.2 g (0.339 mol ) of potassium metal. The addition funnel was charged with a solution of 25.37 g (0.373 mol) of imidazole in 150 mL of THF, which was added over a 1.5 h period. Refluxing the rapidly stirred mixture for 2 h consumed all visible potassium. A solution of 40 mL (0.39 mol) of 2-chloroethyl vinyl ether (CEVE) and 20 mL of THF was added over 1 h, and reflux was maintained an additional 17 h. Precipitated KC1 was removed by filtration, and the solvent evaporated in vacuo. The resulting oil was dried over CaH„ and distilled (131.5-134°C, 4.0 mm), affording 31.2 g of pale-yellow oil. H NMR indicated the presence of imidazole (-25%). The oil was dissolved in THF and stirred over NaH overnight. The precipitate was filtered, and the filtrate concentrated in vacuo and dried over CaH„. Short-path distillation gave 21.86 g (46.7%) of pure 28, bp 90-92°C (0.5 mm), as a colorless oil. The product was stored over CaH ? at room temperature. l H NMR (CDC1 3 , TMS): 3.74-4.40 (m, 6H), 6.38 (X of ABX, 1H), 6.98 (m, 2H), 7.47 (s, 1H). (DMS0-d 6 , TMS): 3.83-4.47 (m, 4H), 6.46 (X of ABX, 1H), 6.93 (t, 1H), 7.15 (t, 1H), 7.60 (s, 1H).

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29 13 C NMR (CDC1 3 , 77.0): 44.93, 65.96, 86.48, 118.35, 128.08, 136.36, 149.89. IR (neat, NaCl): 3115 (m), 2940 (m), 2880 (m), 1620 (br, s), 1506 (s), 1465 (m), 1440 (m), 1365 (s), 1325 (s), 1285 (s), 1230 (s), 1195 (br, s), 1150 (sh, tn), 1110 (s), 1092 (sh, s), 1078 (s), 1038 (s), 1028 (sh, m), 990 (m) , 963 (sh, s), 952 (s), 915 (m) , 906 (s), 820 (br, s), 740 (br, s), 662 (s), 622 (s). LRMS (m/e, rel . intensity): 138 (M + , 19.2), 137 (11.9), 109 (19.4), 108 (96.4), 95 (14.0), 94 (10.0), 86 (19.7), 84 (32.7), 82 (20.0), 81 (100). HRMS: m/e 138.07744 (calcd. for ^H^O = 138.07931). Elemental Analysis: Calcd. for C 7 H 10 N 2 0: C, 60.85; H, 7.29; N, 20.27. Found: C, 60.85; H, 7.32; N, 20.28. N( g-Vi nyl oxyethyl ) pi peri di ne/l-[2( Ethen.yl o xy )ethyl 1 -pi peri di ne L702-06-7I (291 24 This vinyl ether was synthesized via the method of Goette. Thus, to a 250 mL three-necked round-bottomed flask fitted with a magnetic stir bar, condenser, and addition funnel was added 42.5 g (0.506 mol) of NaHC0_, 25 mL of water and 25 mL (0.253 mol ) of piperidine. The addition funnel was charged with 77 mL (0.759 mol) of CEVE and the contents added over a 1.5 h period to the gently refluxing mixture. Reflux was maintained for 17 h after addition was complete. Ether was added to the cool flask, and the organic phase was dried over NaOH for several days. Ether and excess CEVE were removed under reduced pressure. The residue was distilled under vacuum, affording

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30 35.2 g (87.0%) of colorless oil (29), bp 75-76. 5°C (10 mm) [literature bp 72.3-73°C (7.5 mm)]. 24 *H NMR (CDC1 3 , TMS): 1.23-1.88 (m, 4H), 2.22-2.80 (m, 4H), 3.72-4.37 (m, 4H), 6.51 (X of ABX, 1H). 13 C NMR (CDC1 3 , 77.0): 23.73, 25.34, 54.39, 57.26, 64.82, 85.58, 151.18. IR (neat, NaCl): 3120 (w), 3080 (w), 3050 (w), 2940 (s), 2855 (m) , 2780 (m), 2750 (m), 1635 (m), 1610 (s), 1478 (m) , 1455 (m), 1442 (m), 1383 (w), 1352 (m), 1320 (s), 1305 (m), 1280 (m), 1262 (m), 1200 (s), 1160 (m), 1126 (m), 1090 (m), 1080 (m), 1040 (m) , 1023 (w), 1000 (m), 984 (m), 962 (m), 945 (w), 862 (m), 810 (s), 780 (w), 760 (w), 700 (w). 3-Vinyloxyethyl (imidazo!-4yl methyl )piperidinium Chloride (30) 25 The method reported by Tonellato was employed. To a 50 ml_ one-necked round-bottomed flask containing a stir bar was added 1.338 g (8.74 mmol ) of 4-(chloromethyl )imidazole hydrochloride (31) and 10 mL of anhydrous methanol. To the stirred solution at room temperature was added 2.771 g (17.8 mmol) of _29 in one portion, and the solution was stirred for 0.5 h. Approximately 1 g of Na ? C0was added, the mixture stirred for 5 min, and filtered. The filtrate was reduced in volume on a rotary evaporator and suction filtered again. Slow addition of the filtrate into ether gave an oily precipitate, which was taken up in 10 mL of anhydrous methanol, again stirred over ~1 g of Na^CO.,, filtered, and the filtrate reduced in vacuo. The viscous oil was triturated with acetonitrile, suction filtered and reduced in volume. Precipitation into ether gave an oily residue. This process

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31 (treatment with Na 2 C0 3 , etc.) was repeated 2 additional times to ensure complete removal of 29 as its free base. Final drying of the oily precipitate in vacuo overnight afforded 1.998 g (84%, crude) of hydroscopic solid (30). Proton NMR revealed the presence of ether as a major contaminant. *H NMR (D 2 0, DSS): 1.50-2.17 (m, 6H), 3.25-3.69 (m, 6H), 4.17-4.53 (m, 4H), 4.63 (s, 2H), 6.60 (X of ABX, 1H), 7.52 (s, 1H), 7.86 (s, 1H). 13 C NMR (D 2 0, DSS): 22.17, 23.15, 58.87, 59.95, 61.80, 63.94, 91.33, 124.57, 129.11, 140.02, 153.18. IR (KBr): 3600-2500 (br, s), 1625 (s), 1558 (w), 1495 (sh, m) , 1465 (m), 1435 (sh, m), 1370 (m), 1325 (m), 1295 (w), 1195 (s), 1090 (m), 1028 (m), 977 (m), 942 (w), 897 (m), 865 (m), 830 (m), 796 (m), 663 (m), 626 (s). Imidazole and Histamine Derivatives Histamine/lH-Imidazole-4-ethanamine [51-45-6] (20) Free base (2C0 was prepared from histamine di hydrochloride by three methods. Method A. The procedure of Tabor and Mosettig was used. A 2% solution of histamine di hydrochloride in 95% ethanol was slowly trickled through a column of Amberlite IRA-400 ion exchange resin. The percolate was reduced to an oil on a rotary evaporator, and distilled under vacuum, bp 134-135°C (0.075 mm) [literature bp 27 209-210°C (18 mm)], affording a colorless to pale-yellow viscous oil. Distilled yields were generally poor and the purity and boiling point of the product variable.

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32 l H NMR (DMSO-dg, TMS): 2.42-3.00 (m, 4H), 4.97 (br, 3H), 6.77 (s, 1H), 7.54 (s, 1H). Method B. To a 50 mL Erlenmeyer flask was added 5.638 g (0.03063 mol) of histamine dihydrochloride and -10 mL of H-O. To the stirred solution was added in small increments 5.146 g (0.06125 mol) of NaHC0 3! and the flask was allowed to stand overnight. Solvent was removed in vacuo, and the resultant colorless oil was triturated with absolute ethanol. The precipitate was filtered out, and the filtrate reduced in volume in vacuo. Short-path distillation of the resultant oil afforded 1.597 g (46.9%) of 20 as a viscous oil, bp 140-143°C (1.0 mm). Spectral properties of this material were identical to those of 20 made by Method A. Method C. To an Erlenmeyer flask containing 6.728 g (0.0365 mol) of histamine dihydrochloride dissolved in 10 mL of H^O was added 18.25 mL (0.0730 mol) of 4 N NaOH solution. The solution was stirred for 0.5 h, and the solvent was removed in vacuo. The resultant thick oil was triturated with 95% ethanol, filtered, and the filtrate reduced to an oil in vacuo. The oil was distilled in a Kugelrohr apparatus (0.050 mm, ~160°C), affording 3.245 g (80%) of a colorless oil, which crystallized on standing, mp 85-88°C (literature mp 83-84°C). 27 4(Hydroxymethyl ) imi dazol e Hydrochl ori de/lHImi dazol e-4-methanol [32673-41-9] (32) 28 This material was prepared by the method of Totter and Darby. To a 1 L three-necked round-bottomed flask fitted with a mechanical stirrer and reflux condenser was added 250 mL of benzene, 125 mL of water and 50 mL (0.6 mol) of 37% HC1 . The mixture was brought to 80°C

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33 via an oil bath, and 50.0 g (0.153 mol ) of 4( hydroxymethyl ) imidazole picrate was added in one portion. Stirring was continued until all the solid had dissolved, at which time heating was discontinued and the flask allowed to cool. The aqueous phase was extracted 5 times with 150 mL portions of benzene, stirred over -2 g of Norit-A and concentrated in vacuo. Recrystallization from absolute ethanol gave 15.45 g (59.3%) of yellow crystals, mp 105-109°C (literature mp 10728 109°C). A second recrystallization from absolute ethanol gave 14.25 g of pale-yellow crystals, mp 107-110°C. l U NMR (D 2 0, DSS): 5.00 (br, 2H), 7.52 (br, 1H), 8.79 (br, 1H). 13 C NMR (D 2 0, DSS): 56.00, 119.26, 134.95, 136.37. IR (KBr): 3500-2500 (br, s), 1615 (s), 1520 (w), 1458 (s), 1450 (sh, s), 1420 (s), 1362 (m), 1290 (m) , 1258 (m), 1252 (m), 1210 (m) , 1140 (s), 1070 (s), 1032 (s), 974 (m), 920 (m), 870 (m) , 828 (sh, s), 813 (s), 745 (m), 620 (s). 4-(Chloromethyl imidazole Hydrochloride/4-(Ch1oromethyl )-lH-imidazole Hydrochloride [31036-72-3] (31) 29 The procedure of Turner et al . was employed. To a 100 mL threenecked round-bottomed flask equipped with a mechanical stirrer, condenser, drying tube, and addition funnel was added 14.25 g (0.106 mol) of 22 and 10 mL of benzene. The addition funnel was charged with 11 mL (0.15 mol) of thionyl chloride and 20 mL of benzene, ind the solution was added to the rapidly stirred suspension over a 1 h period. The mixture was refluxed for 2 h, and then allowed to stand at room temperature overnight. The solid product was suction filtered, washed with benzene and dried in vacuo. Recrystallization from acetonitrile-

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34 absolute ethanol afforded 11.50 g (71.0%) of off-white crystals, mp 141-144°C (literature mp 144°C). 30 13 C NMR (ethanol -dj, 17.2): 33.23, 117.94, 130.03, 134.56. IR (KBr): 3500-2500 (s, br), 3140 (m), 1615 (m), 1460 (m), 1430 (m) , 1290 (m), 1265 (w), 1168 (w), 1147 (m), 1076 (w), 1062 (m), 978 (m), 922 (m), 900 (m), 853 (m), 808 (tn), 765 (w), 720 (m), 675 (w), 620 (s). Dich1orobis(l-[2-(ethen.yloxy)eth,yl]-lH-imidazole-N 3 )zinc (33) 31 The method of Ei 1 beck et al. was employed. In a 25 mL Erlenmeyer flask was weighed 0.198 g (1.45 mmol ) of ZnCl ? , and 4 mL of absolute ethanol was added. To the stirred solution was added 0.803 g (5.81 mmol) of 28, the transfer aided by 2 mL of ethanol. The solution was stirred for 1 h, at which time anhydrous ether was added dropwise until the solution became turbid. On standing, a colorless oil precipitated from solution. Enough absolute ethanol was added to redissolve the precipitate, and the flask was allowed to stand for 12 days. Upon addition of ether, a white crystalline mass precipitated from solution. The solid was collected, washed with ether, and dried in vacuo, affording 0.535 g (89%) of 33, mp 78.5-80°C. IR (KBr): 3115 (m), 3040 (w), 2925 (w), 2875 (w), 1635 (sh, m) , 1620 (s), 1525 (m), 1442 (w), 1397 (w), 1365 (w) , 1322 (m), 1240 (m), 1232 (m), 1187 (s), 1112 (m) , 1097 (s), 1033 (m) , 992 (m) , 952 (m), 850 (m), 830 (m), 760 (m), 668 (m) , 653 (m), 630 (m). Elemental Analysis: Calcd. for C 14 H 20 N 4 2 -ZnCl 2 : C, 40.75; H, 4.89; N, 13.58; CI, 17.18. Found: C, 40.72; H. 4.91; N, 13.51; CI, 17.09.

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35 Dich1orobis(l-methy1-lH-imidazole-N 3 )zinc-(T-4) [23570-24-3] (34) N-methylimidazole-ZnCk complex was prepared in an analogous manner to 33. Thus, the reaction of 0.294 g (2.16 mmol ) of ZnCL and 1.088 g (13.25 mmol) of N-methyl imidazole in 15 mL of 95% ethanol gave, after precipitation with ether, 0.512 g (79%) of fine-white solid (34), mp 205-208°C (literature mp 209°C). 32 IR (KBr): 3150 (w), 3125 (s), 1695 (w), 1635 (w), 1588 (w), 1535 (m), 1520 (m), 1425 (m), 1287 (m), 1235 (s), 1105 (s), 1092 (s), 1025 (w), 955 (m), 847 (m), 775 (m) , 740 (m) , 668 (m), 653 (s), 620 (m), 615 (m). Elemental Analysis: Calcd. for CgH^N^ZnCl^ C, 31.98; H, 4.02; N, 18.64; CI, 23.60. Found: C, 32.03; H, 4.07; N, 18.59; CI, 23.59. N-[(Ethenyloxy)carbonyl )]-lH-imidazole-4-ethanamine (35) and 7,8-Dihydro5-oxoi mi dazo[l,5-c]pyri mi dine (36) To a 100 mL three-necked round-bottomed flask containing a stir bar and an addition funnel was added 5.522 g (0.030 mol ) of histamine dihydrochloride, 10 mL of water, and 13 mL of dioxane. To the stirred mixture was added in portions 7.562 g (0.090 mol) of NaHC0 3 . The flask was cooled to 0°, and a solution of 3.19 g (0.030 mol) of vinyl chloroformate in 12 mL of dioxane was added over 25 min. The mixture was stirred an additional 0.5 h and then warmed to room temperature. NaCl was filtered, and the filtrate was reduced in volume in vacuo. The resulting oil was chromatographed on a basic alumina column (3:2 CHCl_:methanol eluting solvent). One large fraction was collected; removal of solvent in vacuo gave 2.361 g of yellow oil. H NMR indicated the desired mono acylated product (35_) was present. The oil was

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36 rechromatographed on a silica gel column (4% methanol :CHC1 eluting solvent). Two products were isolated, 35, 0.108 g (2%), mp 88-89°C and 36, 0.260 g (6.3%), mp 219-221°C (dec). 35 ! H NMR (CDC1 3 , TMS): 2.83 (t, 2H), 3.51 (m, 2H), 4.37-4.79 (AB of ABX, 2H), 5.67 (br, 1H), 6.83 (d, 1H), 7.16 (X of ABX, 1H), 7.57 (d, 1H), 9.19 (br, 1H). 13 C NMR (acetone-d 6 , 29.8): 28.05, 41.69, 94.13, 116.46, 135.71, 136.87, 143.15, 154.18. (CDC1 3 , TMS): 27.49, 41.04, 95.28, 115.90, 135.00, 136.12, 142.22, 153.91. IR (KBr): 3220 (m), 3005 (w), 2965 (w), 2940 (w), 1708 (s), 1647 (m), 1570 (m), 1550 (m), 1485 (w), 1450 (m), 1425 (w), 1362 (w), 1310 (m), 1295 (m), 1277 (m), 1260 (m), 1222 (m), 1190 (w), 1158 (m) , 1082 (m), 1040 (m), 983 (m), 974 (m), 952 (m), 860 (m), 820 (m), 785 (m), 764 (w), 735 (w), 700 (w), 617 (m). LRMS (m/e, rel . intensity): 181 (M + , 0.1), 138 (5.9), 137 (30.6), 82 (10.2), 81 (100). HRMS: m/e 181.0828 (calcd. for CLH^N-O,, = 181.0851). Elemental Analysis: Calcd. for CgH^^: C, 53.03; H, 6.12; N, 23.19. Found: C, 53.09; H, 6.14; N, 23.20. 36 l W NMR (DMS0-d 6 , 2.49): 2.84 (t, 2H), 3.26-3.42 (m, 2H), 6.77 (d, 1H), 8.04 (d, 1H), 8.17 (br, 1H). 13 C NMR (DMS0-d 6 , 39.5): 19.27, 38.72, 124.64, 127.33, 134.00, 148.38.

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37 IR (KBr): 3220 (br, m), 3115 (s), 2960 (w), 2940 (w), 2920 (w), 2890 (m), 1735 (sh, s), 1710 (s), 1580 (w), 1473 (m), 1455 (m), 1430 (m), 1410 (s), 1360 (w), 1342 (m), 1327 (m), 1310 (w), 1297 (w), 1258 (w), 1232 (w), 1210 (s), 1180 (m), 1150 (m), 1080 (m) , 1060 (m), 1045 (m), 930 (m), 865 (w), 833 (m), 755 (m), 680 (m),650(m) LRMS (m/e, rel . intensity): 138 (2.5), 137 (M + , 26.5), 81 (100). HRMS: m/e 137.05836 (calcd. for CgH^O = 137.05891). Elemental Analysis: Calcd. for CgHjN-O: C, 52.55; H, 5.14; N, 30.64. Found: C, 52.51; H, 5.17; N, 30.65. N,l-[(Diethenyloxy)carbon,y1]-lH-imidazole-4-ethanamine (37) To a 200 mL three-necked round-bottomed flask equipped with an addition funnel was added 0.97 g (8.7 mmol ) of 20 and 50 mL of ethanolfree CHC1-. The solution was cooled to 0°C, and 1.2 mL (8.6 mmol) of dry triethylamine was added. The addition funnel was charged with 0.88 g (8.3 mmol) of vinyl chloroformate and 50 mL of CHC1,, and the contents were added over a 2.5 h period. The flask was allowed to reach room temperature, and water was added. The organic phase was twice extracted with 50 mL portions of water and dried over anhydrous MgSO.. Removal of solvent in vacuo gave a white solid which was recrystallized from cyclohexane, filtered, and dried in vacuo, affording 0.40 g (38% based on vinyl chloroformate) of 37, mp 99-100°C. ! H NMR (CDC1 3 , TMS): 2.79 (t, 2H), 3.55 (m, 2H), 4.36-5.24 (2 AB of 2 ABX, 4H), 5.40 (br, 1H), 7.09-7.39 (2 X of 2 ABX, 2H), 7.26 (d, 1H), 8.13 (d, 1H). 13 C NMR (CDC1 3 , 77.0): 27.73, 39.96, 94.79, 100.35, 113.65, 136.95, 140.85, 141.67, 141.97, 145.77, 153.42.

PAGE 48

38 IR (KBr): 3240 (m), 3145 (w), 3050 (m), 2940 (w), 1775 (s), 1735 (s), 1640 (m), 1587 (m), 1560 (m), 1488 (m), 1453 (w), 1440 (w), 1406 (s), 1370 (m). 1327 (m), 1295 (m), 1265 (s), 1247 (s), 1215 (m) , 1197 (m), 1173 (m), 1138 (m), 1108 (m) , 1055 (m) , 1010 (m), 982 (m), 965 (w), 952 (m), 943 (m), 880 (m) , 847 (m), 838 (m), 752 (m), 730 (m), 680 (w), 668 (w). LRMS (m/e, rel. intensity): 253 (0.3), 252 (0.7), 251 (M + , 0.8), 210 (2.0), 209 (5.2), 208 (40.0), 207 (8.7), 164 (21.3), 152 (26.9), 151 (38.9), 138 (34.0), 137 (13.0), 95 (24.7), 81 (100). HRMS: m/e 251.0899 (calcd. for C^H^O. = 251.0906). Elemental Analysis: Calcd. for C^H^NgO-: C, 52.59; H, 5.22; N, 16.73. Found: C, 52.58; H, 5.31; N, 17.21. 4-An,ylimidazole/4-(2-Propenyl)-lH-imidazo1e [50995-98-7] (38) A 250 mL three-necked round-bottomed flask, mechanical stirring rod, condenser, and addition funnel were assembled while hot and cooled by flushing with N„. To the flask was added 3.408 g (0.140 mol) of Mg turnings; the addition funnel was charged with 100 mL of freshly distilled THF and 10 mL (0.142 mol) of vinyl bromide. Reaction was initiated by addition of a solution of a drop of ethylene bromide in 10 mL of THF. The vinyl bromide solution was then added at a rate which maintained a gentle reflux. When formation of Grignard reagent was complete, the solution was cooled to 0°C via an external ice bath. To the flask was added 4.289 g (0.0280 mol) of 31 in -15 equal portions over a 2.5 h period. The rapidly stirred mixture was maintained at 0°C for an additional 0.5 h, then allowed to warm to room temperature and was quenched by careful addition of 20 mL of

PAGE 49

39 saturated NH.Br. Additional water was added to dissolve the precipitated salts, and the organic layer was separated. The aqueous layer was extracted with 2-150 mL portions of CHC1.,, and the combined organic fractions were dried over anhydrous MgSO.. Solvent was removed in vacuo, giving dark-yellow oil. This oil was chromatographed on a column of silica gel using a mixture of CHCUiCH-OH (95:5) as eluting solvent. Fractions were combined which gave an R f = 0.30 by TLC [silica gel, CHC1 3 :CH 3 0H (95.5)]. Removal of solvent in vacuo afforded 1.372 g (45%) of pale-yellow oil (38) having identical l H 33 NMR properties as reported by Begg et al . *H NMR (CDC1 3 , TMS): 3.30-3.45 (m, 2H), 5.00-5.20 (m, 2H), 5.79-6.20 (m, 1H), 6.81 (d, 1H), 7.60 (d, 1H), 11.05 (br, 1H). 13 C NMR (CDC1 3 , TMS): 31.39, 116.14, 117.31, 134.76, 135.25, 135.78. IR (neat, NaCl ) : 3500-2300 (br, s), 3080 (m), 3015 (w), 2985 (m), 2850 (br, m), 2740 (w), 2640 (w), 1640 (m), 1588 (m) , 1570 (m) , 1473 (br, m), 1430 (m), 1323 (w), 1298 (m), 1262 (m), 1230 (m) , 1195 (w), 1160 (w), 1105 (m), 1088 (m), 990 (s), 940 (m), 915 (s), 820 (m), 750 (m), 662 (m), 625 (m). LRMS (m/e, rel . intensity): 109 (6.6), 108 (M + , 68.4), 107 (100), 82 (20.7), 81 (85.5), 80 (86.2), 54 (26.8), 53 (40.9). HRMS: m/e 108.06875 (calcd. for C 6 HgN 2 = 108.06875). 4-Nitroimidazo1e/4-Nitro-lH-imidazole [3034-38-6] (39) This material was prepared in accordance with the method of 34 Stambaugh and Manthei in 31% yield, mp 308-309°C (literature mp 308-310°C). 34 *H NMR (DMS0-d 6 , 2.49): 7.83 (d, 1H), 8.29 (d, 1H).

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40 Other Monomers 2-Propenylphenol/(E) and (Z)-2-(l-Propen.yl )-phenol [6380-21-8] (40) This monomer was synthesized via the isomerization of 2-allyl35 phenol as reported by Tarbell. The product consisted of both E and Z isomers (87%), bp 115-123°C (17 mm), [literature bp 110-115°C (1516 mm)]. 35 l H NMR (CDC1 3 , TMS): 1.69 and 1.86 (2 d of d, 3H), 5.34 (br, 1H), 5.85-7.34 (m, 6H). 13 C NMR (CDC1 3 , 77.0): 14.42, 18.71, 115.11, 115.70, 120.33, 120.86, 123.93, 125.25, 127.20, 127.83, 127.98, 128.47, 129.73, 130.86, 152.15. IR (neat, NaCl): 3540-3300 (br, s), 3060 (m), 3035 (m), 2960 (m), 2935 (m), 2910 (m), 2875 (w), 1850 (m), 1730 (w), 1655 (w), 1605 (m), 1580 (m), 1495 (s), 1483 (s), 1450 (s), 1330 (br, m), 1282 (m), 1225 (br, s), 1172 (s), 1150 (m), 1105 (m), 1080 (m), 1037 (m), 965 (s), 945 (sh, m), 840 (m), 790 (m), 750 (s), 717 (m), 610 (m). Isoeugenol/2-Methoxy-4-(l-propenyl )-phenol [97-54-1] (41) Isoeugenol was obtained from the Aldrich Chemical Co. and was distilled before use, bp 138. 5-140. 5°C (9 mm), [literature bp 140°C (12 mm)]. 27 X H NMR (CDC1 3 , TMS): 1.82 (d, 3H), 3.80 (s, 3H), 5.72 (s, 1H), 5.766.38 (m, 2H), 6.81 (s, 3H). 13 C NMR (CDC1 3 , TMS): 18.27, 55.80, 108.05, 114.44, 119.31, 123.31, 130.81, 144.80, 146.65.

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41 IR (neat, NaCl): 3540-3400 (s, br), 3015 (m), 2960 (m), 2935 (m), 2910 (m), 2880 (w), 2845 (m), 2730 (w), 1590 (m), 1510 (vs), 1462 (s), 1450 (s), 1423 (s), 1370 (m), 1260 (br, s), 1230 (s), 1205 (s), 1153 (s), 1120 (s), 1030 (s), 960 (m) , 920 (w) , 905 (w), 855 (m), 820 (m), 802 (m), 783 (m) , 755 (w), 732 (w). trans-Anethole/(E)-l-Methoxy-4-(l-propenyl )-benzene [4180-23-8] (42) This material was purchased from the Aldrich Chemical Co. and was used without further purification. l H NMR (CDC1 3 , TMS): 1.82 (d, 3H), 3.73 (s, 3H), 5.92-6.42 (m, 2H), 7.01 (ABq, 4H). 13 C NMR (CDC1 3 , 77.0): 18.32, 55.12, 113.85, 123.30, 126.86, 130.37, 130.81, 158.64. IR (neat, NaCl): 3029 (m), 3000 (m), 2955 (m) , 2930 (m), 2910 (m), 2880 (w), 2835 (w), 2730 (w), 1650 (w), 1605 (s), 1575 (m) , 1505 (vs), 1462 (br, m), 1440 (m), 1415 (w), 1375 (w), 1305 (m), 1280 (m), 1245 (s), 1210 (w), 1175 (m), 1110 (m), 1035 (s), 962 (m), 940 (m), 837 (m), 785 (m), 755 (m), 710 (w). N-Ethy1maleimide/l-Ethyl-lH-pyrrole-2,5-dione [128-53-0] (43) This monomer was purchased from the Aldrich Chemical Co. (Gold Lable) and was used without further purification. Diethylfumarate/(E)-2-Butenedioic acid, diethyl ester [623-91-6] (44) Di ethyl fuma rate (44) was obtained from the Bordon Chemical Co. and was distilled from CaH 2 under reduced pressure, bp 83.5-84°C (4.3 mm) [literature bp 75°C (5 mm)]. 36 : H NMR (CDC1 3 , TMS): 1.33 (t, 3H), 4.28 (q, 2H), 6.82 (s, 2H).

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42 Fumaronitrile/(E)-2-Butenedinitrile [764-42-1] (45) This monomer was purchased from the Aldrich Chemical Co. Recrystallization of 45 from benzene gave white needles, mp 94-96. 5°C (literature mp 95-97°C). 37 *H NMR (CDC1 3 , TMS): 6.29 (s, 2H). N-Vinylimidazole/1-Ethenyl-lH-imidazole [1072-63-5] (46) This monomer was purchased from Polysciences , Inc. and distilled from CaH 2 before use, bp 89-90°C (17 mm). l H NMR (CDC1 3 , TMS): 4.77-5.33 (AB of ABX, 2H), 6.89 (X of ABX, 1H), 7.07 (s, 1H), 7.18 (s, 1H), 7.66 (s, 1H). 13 C NMR (acetone-d 6 , 29.8): 101.15, 116.55, 130.10, 130.30, 137.02. Maleic Anhydride/2, 5-Furandione [108-31-6] (47) Maleic anhydride was obtained from Fisher Scientific Co. and was sublimed at atmospheric pressure (80°C) prior to use, mp 50.5-53°C (literature mp 52.8°C). 27 Homopolymers Poly(N-Acetoxymaleimide) (48) To a heavy-walled polymerization tube was added 2.021 g (0.0130 mol) of 11 , 0.0211 g (0.128 mmol ) of AIBN, and 25 mL of freshly distilled CH 2 C1 2 . After all the solid had dissolved, the tube was degassed (3 freeze-pump-thaw cycles) and sealed at ~10~ 5 mm. Polymerization was carried out in a constant temperature bath (61°C) for 66 h. The tube was opened and the contents precipitated into ether. The solid was collected, redissolved in dioxane and reprecipitated into ether. The solid was again collected and dried in a vacuum oven (100°C) overnight to afford 1.614 g (80% conversion) of pink powder (48)

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43 l H NMR (DMS0-d 6 , TMS): 2.34 (br-s, 3H), 3.45, 4.13 (br, 2H). 13 C NMR (CD 3 CN-C1 2 CHCHC1 2 , 60°C, 1.30): 17.43, 42.19, 165.74, 169.05, 170.95. IR (KBr): 2940 (w), 1820 (s), 1790 (s), 1730 (vs), 1625 (w), 1430 (w), 1373 (m), 1220 (s), 1160 (s), 1055 (m), 1000 (w), 820 (m), 725 (w), 640 (m). Elemental Analysis: Calcd. for CgHgNO,: C, 46.46; H, 3.25; N, 9.03. Found: C, 45.74; H, 3.38; N, 8.88. VPO (acetone): M p = 3850 g/mol . Polypheny! N-Maleimidyl Carbonate) (49) To a heavy-walled polymerization tube was added 3.143 g (0.01348 mol) of 13, 0.0250 g (0.152 mmol ) of AIBN, and 6 mL of distilled acetone. The tube was transferred to a high-vacuum line, degassed in -5 the usual manner and sealed at -10 mm. The polymerization was carried out in a constant temperature bath (60°C) for 89 h. The tube was opened, and the solution was slowly added dropwise to a beaker of vigorously stirred ether. The precipitate was collected and dried in vacuo giving 2.755 g (87% conversion) of pale-green solid (49). l H NMR (CD 3 CN, 1.93): 3.99 (br, 2H), 7.32 (br, 5H). 13 C NMR (CD 3 CN, 70°C, 1.30): 42.92, 121.39, 128.50, 131.18, 150.63, 151.95, 169.49. IR (KBr): 3060 (w), 2940 (w), 1825 (s), 1795 (s), 1735 (vs), 1600 (w), 1588 (m), 1490 (m) , 1457 (m), 1375 (m), 1290 (m) , 1225 (br, vs), 1160 (m), 1115 (w), 1070 (s), 1020 (m), 1005 (m), 960 (m), 905 (w), 840 (w), 775 (m), 750 (m), 682 (m), 630 (m).

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44 Elemental Analysis: Calcd. for C-jfLNO-: C, 56.66; H, 3.03; N, 6.01. Found: C, 55.44; H, 3.11; N, 6.17. Poly(N-Hydroxymaleimide) (50) from 48 To a 50 mL Erlenmeyer flask containing a stir bar was added 1.0 g (0.0144 mol ) of hydroxylamine hydrochloride and 20 mL of freshly distilled methanol. To the stirred solution was added 3.9 mL (0.0144 mol) of 3.7M sodium methoxide. After 0.5 h, the mixture was suction filtered. To the filtrate was added a solution of 48 in CD^CN and CI pCHCHCl 2 (NMR sample -150 mg), the transfer aided by rinsing the tube with acetone. The resulting mixture (pink ppt.) was stirred for 48 h, and the solvents were then removed in vacuo. Trituration of the resulting solid with water gave pink solid which was suction filtered and dried in vacuo. 13 C NMR (acetone-d 5 , 29.80): 42.03, 172.75. IR (KBr): 3640-2300 (br, m), 3470 (br, m), 2920 (w), 2800 (w), 1785 (m), 1700 (br, vs), 1620 (m), 1470 (br, m), 1385 (w), 1340 (w), 1230 (s), 1120 (m), 1070 (m), 728 (m), 645 (m). Poly(N-Hydroxymaleimide) (50) from 49 To a 50 mL round-bottomed flask containing a stir bar was added 1.411 g (6.05 mrnol of repeat units) of 49 and 20 mL of methanol. A reflux condenser was attached, and the mixture was refluxed for 20 h. The cooled solution was precipitated into 200 mL of benzene-pentane (2:1). The solid was reprecipitated from acetone into ether, filtered, and dried in vacuo, giving 0.605 g (88%) of tan powder (50). The product decomposed above 265°C. The IR spectrum of this material was identical to that of 50 derived from 48.

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45 Elemental Analysis: Calcd. for C 4 H 3 N0 3 : C, 42.49; H, 2.67; N, 12.39. Found: C, 43.75; H, 3.40; N, 11.94. Poly[N-(4-Carbethox,yphenyl )maleimidel (51) To a heavy-walled polymerization tube was added 3.423 g (0.01396 mol) of 16, 0.0270 g (0.164 mmol ) of AIBN, and 10 mL of freshly distilled DMF. When all the solid had dissolved, the tube was degassed -5 (3 freeze-pump-thaw cycles) and sealed at -10 mm. Polymerization was carried out in an oil bath (75°C) for 44 h. The tube was opened, and most of the DMF was removed in vacuo. The resulting oil was dissolved in 5 mL of acetone and precipitated into ether. The solid was reprecipitated from acetone into ether, collected, and dried in vacuo to give 2.102 g (61% conversion) of pink solid (51) . l H NMR (acetone-d 6 , 50°C, TMS): 1.36 (br, 3H), 4.33, 4.40 (br, 4H), 7.47, 8.08 (br, 4H). 13 C NMR (acetone-d 6 , 50°C, 29.8): 14.55, 41.74, 45.64, 61.77, 127.47, 130.74, 136.44, 165.83, 175.82. IR (KBr): 2985 (m), 2940 (w), 2910 (w), 1785 (sh, m), 1715 (vs), 1610 (m), 1510 (m), 1470 (w), 1445 (w), 1415 (sh, m), 1385 (s), 1280 (s), 1185 (s), 1110 (s), 1020 (m), 855 (m) , 768 (m), 740 (m), 695 (m), 640 (m). Elemental Analysis: Calcd. for C^HjjNO,: C, 63.67; H, 4.52; N, 5.71, Found: C, 63.13; H, 4.67; N, 6.05. Poly[N-(g-Vinyloxyethyl) imidazole] (52) All attempts to obtain homopolymer (52_) of moderate molecular weight and in good yield were unsuccessful. Low yields of oligomers were generally obtained. Polymerization reaction conditions are described in Chapter III, p. 97.

PAGE 56

46 Copolymers N-(g-Viny1oxyethyl imidazole N-Hydroxymaleimide Alternating Copolymer (53) ~ To a 100 mL round-bottomed flask was added 2.325 g (0.0168 mol ) of 28 and 39.95 mL (0.0168 mol) of 0.4 N HC1 . Most of the water was removed on a rotary evaporator at room temperature. The resultant viscous oil was transferred to a heavy-walled polymerization tube aided by a few mL of deionized water. Into a 5 mL volumetric flask was placed 2.223 g (0.0143 mol) of 11, and the flask was diluted to the mark with distilled THF. This solution was added to the polymerization tube (previously cooled to -78°C), and the volumetric flask was rinsed with 3 mL of THF. Finally, 0.0847 g (0.313 mmol ) of K^Og and 0.1237 g (0.315 mmol) of Fe (NH 4 ) 2 (S0 4 ) 2 -6H 2 were added. The final volume of solution was 22 mL. The tube was then degassed on a highvacuum line (3 freeze-pump-thaw cycles) and sealed at -10" mm. The tube was placed in a 30.0°C water bath for 91 h. The tube was opened and the contents precipitated into CH_CN. The acetonitrile was decanted off, and the oily precipitate was taken up in 40 mL of 1 N HC1 and dialized (2000 MW retention) against deionized water for several days. The precipitated solid was suction filtered and dried in vacuo to afford 0.844 g (20% conversion) of light-brown solid (53). X H NMR: See Appendix, p. 122. 13 C NMR: See Chapter III, p. 80. IR (KBr): 3600-3320 (br, m), 3140 (m), 2940 (w) , 1780 (m), 1705 (vs), 1575 (w), 1440 (w), 1400 (w), 1355 (w), 1290 (w), 1230 (s), 1105 (s), 1080 (s), 835 (w), 760 (w), 665 (w), 625 (w).

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47 Elemental Analysis: Calcd. for C^H-JI^: C, 52.59; H, 5.21; N, 16.73. Found: C, 49.78; H, 4.97; N, 14.68; S, 0.53. VPO (DMSO): M n = 488 g/mol . Intrinsic Viscosity (0.1 N HC1 , 30.0°C): [n] = 0.112 dL/g. lorobis(l-[2-(ethenyloxy)eth.yl]-lH-in maleimide Alternating Copolymer (54) Dichlorobis(l-[2-(ethenyloxy)ethyl]-lH-imidazole-N ) zinc-N-AcetoxyT o a heavy-walled polymerization tube was added a solution of 0.327 g (2.40 mmol ) of ZnCl 2 in 6 mL of distilled THF, followed by a solution of 0.630 g (4.56 mmol) of 28 in THF (3 mL). To this solution was added 0.703 g (4.53 mmol) of 11, 0.0075 g (0.046 mmol) of AIBN, and 6 mL of THF. The solution was degassed on a vacuum line and sealed at ~10 mm. Polymerization was carried out at 70°C for 3.5 h. The white precipitate was filtered, washed with THF and dried in vacuo. The material was extracted (Soxhelet) with THF for 3 days and dried in vacuo, affording 1.110 g (67.5% conversion) of white solid (54) which decomposed above 220°C. 13 C NMR: See Chapter III, p. 89. IR (KBr): 3640-3340 (br, m), 3135 (m), 2940 (m), 2880 (w) , 1818 (s), 1785 (s), 1730 (vs), 1650 (br, w), 1522 (m), 1440 (m), 1370 (m), 1290 (w), 1220 (s), 1165 (s), 1110 (s), 1095 (s), 1065 (m), 950 (m), 830 (m), 755 (m), 655 (m), 625 (w). Elemental Analysis: Calcd. for C 26 H 3Q N 6 10 ' ZnCl 2 : C, 43.20; H, 4.18; N, 11.63; CI, 9.81. Found: C, 42.35; H, 4.18; N, 10.98; CI, 9.22. Intrinsic Viscosity (DMSO, 30.0°C): [n] = 0.043 dL/g.

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48 N( 3Vi nyl oxyethyl imidazole -Fumaronitrile Copolymer (55) To a heavy-walled glass polymerization tube was added 1.878 g (0.0136 mol) of 28, 1.116 g (0.0143 mol ) of 45, 0.0466 g (0.284 mmol ) of AIBN, and 25 mL of distilled CH 2 C1 2 The tube was transferred to a high-vacuum line, degassed via several freeze-pump-thaw cycles and -5 sealed at -10 mm. The polymerization was carried out at 60°C for 44 h, resulting in red solution containing an oily dark precipitate. The tube contents were poured into ether. The oily precipitate was taken up in acetone-methanol and precipitated into chloroform. The solid was reprecipitated from acetone into carbon tetrachloride and dried in vacuo (room temperature) overnight, affording 0.367 g of mustard-brown powder. The mother liquors (from precipitations) were combined and reduced in volume on a rotary evaporator. Precipitation into chloroform gave an additional 0.525 g of dark-brown powder. IR (KBr): 3150 (m), 2970 (m), 2940 (m), 2250 (m), 2200 (s), 2140 (m), 1620 (s), 1545 (m), 1440 (m), 1420 (m) , 1355 (w), 1330 (m), 1290 (m), 1170 (m), 1080 (m), 1035 (w), 830 (m), 750 (m), 665 (m), 625 (m). Elemental Analysis: Calcd. for ^H^N.O: C, 61.10; H, 5.59; N, 25.91. Found: C, 60.53; H, 4.38; N, 28.62. N-(g-Vi nyl oxyethyl )imidazo1e-Pi ethyl fuma rate Copolymer (56) To a polymerization tube was added 1.202 g (8.70 mmol) of 28, 1.199 g (6.96 mmol) of 44, 0.0114 g (0.0694 mmol) of AIBN and 25 mL of distilled acetone. The tube contents were degassed (4 freezepump-thaw cycles) and the tube sealed at -10 mm. Polymerization was carried out at 60°C for 90 h. The acetone solution was

PAGE 59

49 precipitated into cold ether, and the gummy precipitate was dried in a vacuum oven (50°C, 48 h) to give 0.262 g of brittle solid (56). 13 C NMR: See Appendix, p. 123. IR (KBr): 3110 (w), 2980 (m), 2940 (m), 2905 (w), 2870 (w), 1730 (vs), 1595 (m), 1505 (m) , 1465 (m), 1445 (m), 1370 (m), 1230 (br, s), 1175 (s), 1160 (s), 1095 (m), 1075 (m), 1025 (s), 905 (w), 855 (m), 815 (w), 740 (m), 660 (m), 620 (w). Elemental Analysis: Calcd. for C^H^N^: C, 58.05; H, 7.14; N, 9.03. Found: C, 56.82; H, 7.11; N, 6.23. Isoeugenol --Maleic Anhydride Copolymer (57) To a dry heavy-walled polymerization tube was added 2.758 g (0.0168 mol ) of 41 and a solution of 1.652 g (0.0168 mol ) of 47 and 0.0555 g (0.338 mmol ) of AIBN in 10 mL of distilled acetone. The solution immediately turned yellow in color. The tube contents were degassed on a high-vacuum line and the tube sealed at ~10 -5 mm. Polymerization was carried out at 60°C for 72 h. The viscous acetone solution was added dropwise to a beaker of rigorously stirred CH ? C1„, the precipitate filtered and dried in vacuo affording 2.725 g (62% conversion) of white solid (57). 13 C NMR: See Appendix, p. 124. IR (KBr): 3580-3300 (m), 2965 (w), 2940 (w), 1855 (m) , 1775 (vs), 1605 (m), 1515 (s), 1460 (m), 1430 (m), 1370 (m), 1275 (s), 1235 (s), 1215 (sh, s), 1155 (m), 1130 (m), 1080 (m). 1030 (m), 920 (s), 825 (m), 785 (w), 735 (w), 645 (w). Elemental Analysis: Calcd. for C 14 H 14 5 : C, 64.12; H, 5.38. Found: C, 63.47; H, 5.61.

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50 VPO (acetone): M = 6950 g/mol. Intrinsic Viscosity (acetone, 30.0°C): [n] = 0.183 dL/g. 2-Propenyl phenol -Maleic Anhydride Copolymer (58) To a dry heavy-walled polymerization tube was added 2.331 g (0.0174 mol) of 40 and a solution of 1.703 g (0.0174 mol ) of 47 and 0.0542 g (0.330 mmol ) of AIBN in 10 mL of distilled acetone. The solution became yellow, and the color persisted throughout polymerization. The tube contents were degassed and the tube sealed at -10 mm. Polymerization was carried out at 60°C for 44 h. The viscous acetone solution was added dropwise to a beaker of vigorously stirred CH 2 C1 2 . The precipitate was filtered and dried in vacuo, affording 3.510 g (87% conversion) of white solid (58). 13 C NMR: See Appendix, p. 125. IR (KBr): 3660-2500 (m, br), 1855 (m), 1770 (s, br), 1610 (m), 1585 (m), 1485 (m), 1455 (m), 1365 (m, br), 1225 (s), 1150 (s, br), 920 (m, br), 755 (s). Elemental Analysis: Calcd. for C^H-^: C, 67.24; H, 5.21. Found: C, 63.94; H, 5.69. VPO (acetone): M p = 21,200 g/mol. Intrinsic Viscosity (acetone, 30.0°C): [n] = 0.231 dL/g. Isoeugenol -N-[2-(4-Imidazolyl )eth.yl]maleimide Copolymer (59) A 25 mL three-necked round-bottomed flask fitted with a stir bar, condenser, and gas inlet tube was assembled hot and cooled via flushing with Ar. To the flask was introduced 0.3463 g (1.32 mmol of repeating units) of 57 and ~2 mL of distilled DMF. To this solution was added 0.1707 g (1.54 mmol) of 20 in 0.5 mL of DMF. A white

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51 precipitate was observed. The mixture was refluxed for 6 h and allowed to cool. The viscous solution was added dropwise to a beaker of rapidly stirred CHC1-; the precipitate was filtered and dried in vacuo. The product was subjected to Soxhelet extraction with CHC1, for 48 h and dried in vacuo, affording 0.473 g of off-white solid ( 59 ) 13 C NMR: See Appendix, p. 126. IR (KBr): 3550-2500 (br, m), 3140 (m), 1765 (m), 1690 (s), 1615 (m), 1595 (m), 1510 (m), 1445 (m), 1400 (m), 1360 (m) , 1270 (m), 1225 (br, m), 1160 (m), 1130 (m), 1080 (w), 1025 (m), 900 (br, w), 820 (m), 785 (m), 650 (w), 620 (m). Elemental Analysis: Calcd. for C ig H 21 N 3 4 : C, 64.21; H, 5.96; N, 11.82. Found: C, 58.75; H, 5.66; N, 10.68. 2-Propenylphenol--N-[2-(4-Imidazo1,yl )ethyl]ma1eimide Copolymer (60) Copolymer 60 was prepared from 58 by the same method as copolymer J5_9 . Thus, 0.383 g (1.65 mmol of repeat units) of 58 was combined with 0.198 g (1.78 mmol) of 20 in refluxing DMF to give 0.470 g of off-white product (60). IR (KBr): 3650-2500 (br, m), 2960 (m), 1765 (m), 1690 (s), 1590 (m), 1483 (m), 1450 (m), 1400 (m), 1360 (m) , 1255 (m), 1220 (m), 1160 (m), 1100 (m), 980 (w), 935 (w), 830 (w), 755 (m) , 660 (w), 615 (w). Elemental Analysis: Calcd. for c 18 H i9 N 3°3 : c > 66.45; H, 5.89; N, 12.91. Found: C, 62.00; H, 5.56; N, 10.55.

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52 trans-Anethole -Maleic Anhydride Copolymer (61) To a polymerization tube was added 1.630 g (0.0166 mol) of 47 , 0.0534 g (0.325 mmol ) of AIBN, 2.464 g (0.0166 mol) of 42, and 10 mL of distilled acetone. The tube contents were degassed in the usual -5 manner and sealed at -10 mm. Polymerization was carried out for 20 h at 60°C. The gelatinous mass was dissolved in DMF and precipitated into ether. The precipitate was filtered and dried in a vacuum oven (90°C, 1 mm) for 48 h, affording 2.065 g (50% conversion) of white solid (61) . 13 C NMR: See Appendix, p. 127. IR (KBr): 2960 (m), 2940 (m), 2840 (w), 1860 (m), 1780 (vs), 1610 (m), 1580 (w), 1510 (s), 1465 (m), 1440 (m), 1390 (w), 1335 (m) , 1305 (m), 1255 (s), 1180 (s), 1080 (m), 1030 (m), 920 (s), 830 (m), 815 (sh, m), 738 (m). Elemental Analysis: Calcd. for C 14 H 14 4 : C, 68.28; H. 5.73. Found: C, 68.11; H, 5.77. trans-Anethole -N-[2-(4-Imidazol,yl )ethyl]maleimide Copolymer (62) Copolymer 62 was prepared from 6J. by the same method as copolymers 59 and 60. Thus, 0.422 g (1.71 mmol of repeat units) of 61^ was combined with 0.200 g (1.80 mmol) of 20 in refluxing DMF to give 0.402 g of off-white product (62). IR (KBr): 3440-2800 (br, m), 2940 (m) , 2840 (m), 1770 (m), 1695 (s), 1610 (m), 1580 (w), 1510 (s), 1460 (sh, m), 1440 (m), 1400 (m) , 1355 (m), 1300 (w), 1250 (m), 1180 (m), 1160 (m), 1105 (w), 1085 (w), 1030 (m), 975 (w), 930 (w), 830 (m), 730 (w), 660 (w), 615 (m).

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53 Isoeugenol -N-Ethylmaleimide Copolymer (63) To a polymerization tube was added 1.5315 g (0.0122 mol ) of 43 , 0.0397 g (0.242 mmol ) of AIBN, 2.010 g (0.0122 mol) of 41, and 10 mL of distilled acetone. The tube contents were degassed and the tube sealed at -10 mm. Polymerization was carried out at 60°C for 38 h. The acetone solution was added dropwise to a vigorously stirred beaker of ether. The precipitate was filtered and dried in vacuo, affording 3.117 g (88% conversion) of white solid (63). 13 C NMR: See Appendix, p. 128. IR (KBr): 3680-3100 (br, m), 2970 (m), 2940 (m), 2880 (w), 2840 (w), 1770 (m), 1690 (vs), 1600 (m), 1510 (s), 1450 (m), 1405 (s), 1375 (m), 1350 (m), 1270 (m), 1225 (s), 1130 (m), 1030 (m) , 940 (w), 895 (w), 860 (w), 810 (m), 790 (m), 770 (w), 730 (w), 650 On). Elemental Analysis: Calcd. for C 16 H ig N0 4 : C, 66.42; H, 6.62; N, 4.84. Found: C, 65.66; H, 6.64; N, 5.03. VP0 (acetone): M = 25,200. Intrinsic Viscosity (acetone, 30.0°C): [n] = 0.276 dL/g. 2-Propenylphenol -N-Ethylmaleimide Copolymer (64) To a polymerization tube was added 1.8594 g (0.01486 mol) of 43, 0.0485 g (0.295 mmol) of AIBN, 1.994 g (0.01486 mol) of 40, and 10 mL of distilled acetone. The tube contents were degassed in the usual manner and the tube sealed (~10~ mm). Polymerization was carried out at 60°C for 38 h. The acetone solution was added dropwise to ethyl ether, the precipitate filtered and dried in vacuo, affording 1.286 g (33% conversion) of white solid (64).

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54 13 C NMR: See Appendix, p. 129. IR (KBr): 3660-3100 (br, m), 2975 (m), 2940 (m) , 2880 (w), 1770 (m) , 1695 (vs), 1605 (m), 1500 (m), 1485 (m) , 1450 (s), 1405 (s), 1378 (m), 1350 (s), 1225 (s), 1135 (m), 1095 (m), 1040 (w), 935 (m), 850 (w), 830 (w), 810 (m), 755 (m), 680 (w). Elemental Analysis: Calcd. for C 15 H 17 N0 3 : C, 69.48; H, 6.61; N, 5.40, Found: C, 67.01; H, 6.51; N, 6.25. Intrinsic Viscosity (acetone, 30.0°C): [n] = 0.083 dL/g. Miscellaneous Reactions Reaction of N-Acetoxymaleimide (11) and N-(B-Vin,yloxyethyl ) imidazole (28). Preparation of N-Acetoxymaleimide Cyclotrimer (65) To a 50 mL Erlenmeyer flask was added 4.038 g (0.0260 mol ) of U and 10 mL of CH^C^. To this colorless solution was added a solution of 0.0180 g (0.130 mmol ) of 28 in 1 mL of CH 2 C1 2 . Immediately a red color became apparent which intensified with time. The flask was allowed to stand at room temperature for 165 h. The dark-red solution was added dropwise to a beaker of vigorously stirred ether. The precipitate was filtered and dried in vacuo at 100°C to afford 0.66 g (16.3%) of purple powder (65). *H NMR (CD 3 CN, TMS): 2.29 (br, ~3H), 3.00-4.60 (br-m, ~2H). 3 C NMR: See Appendix, p. 130. IR (KBr): 2945 (w), 1820 (s), 1790 (s), 1740 (vs), 1430 (w), 1375 (m), 1225 (s), 1160 (s), 1065 (m), 1005 (w), 820 (m), 670 (w), 645 (w). Elemental Analysis: Calcd. for (C^NO^: C, 46.46; H, 3.25; N, 9.03. Found: C, 46.40; H, 3.24; N, 9.03.

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55 LRMS (m/e, rel. intensity): 465 (m + , 0.1), 423 (0.4), 113 (0.4), 60 (19.3), 45 (24.4), 44 (61.8), 43 (100). VPO (acetone): M n = 488 g/mol Reaction of Maleic Anhydride (47) and N-(g-Vinyloxyethyl imidazole (28] To a 125 mL Erlenmeyer flask was added 0.967 g (7.00 mmol ) of 28 and 20 mL of CHpCl 2 . To this colorless solution was added 0.687 g (7.00 mmol) of 47. The solution immediately turned yellow in color and eventually became brown. The flask was allowed to stand for 11 days. The solution was decanted, leaving a black precipitate which was removed from the flask and stirred with 100 mL of acetone for 3 h. The solid was filtered and dried in vacuo, affording 0.897 g of brown powder. IR (KBr): 3650-2320 (br, m), 3140 (m), 2950 (w) , 1770 (s), 1720 (br, s), 1620 (m), 1580 (m), 1555 (m), 1445 (w), 1380 (br, m), 1220 (br, m), 1190 (m), 1135 (m), 1085 (m), 1035 (m), 935 (m) , 830 (m), 750 (m), 665 (w), 625 (m). Reaction of N-H.ydroxymaleimide (14) and N-(B-Vinyloxyethyl )imidazole (28) To a 50 mL Erlenmeyer flask was added 0.326 g (2.88 mmol) of 14 and 10 mL of distilled acetone. To this pale yellow solution was added 0.406 g (2.94 mmol) of 28. The solution immediately assumed a darker yellow color, and a precipitate began to form. After stirring for 20 h, the precipitate was filtered, washed with acetone and dried in vacuo, affording 0.421 g of yellow solid which decomposed upon heating to 180°C.

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56 IR (KBr): 3140 (w), 3100 (w), 2940 (w), 1785 (m), 1695 (br, s), 1615 (m), 1570 (w), 1555 (w), 1540 (w), 1415 (w), 1360 (w), 1320 (w), 1235 (br, m), 1190 (m), 1080 (m) , 955 (w), 830 (w), 740 (w), 690 (m). Elemental Analysis: Calcd. for (C 4 H 3 N0 3 ) 3 -C 7 H 1Q N 2 0'H 2 0: C, 46.06; H, 4.27; N, 14.14. Found: C, 45.92; H, 4.21, N, 13.96. Kinetic Measurements Equipment and Materials Pseudo first-order kinetics were measured on Cary 17-D or PerkinElmer 330 spectrophotometers. Temperature control was provided by a Lauda K-2/R (40.0 ± 0.2°C) or a Haake A80 (25.0 ± 0.2°C) constant temperature apparatus. A Corning-125 pH meter fitted with a Ag/AgCl pH electrode was used to measure the pH of solutions before and after the reaction with substrate. p-Nitrophenyl acetate (PNPA) was obtained from the Aldrich Chemical Co. and was recrystallized from cyclohexane before use, mp 77-78°C (literature mp 81-82°C). 38 2,4-Dinitrophenyl benzoate (DNPB) was kindly supplied by Ms. Ann Mobley. Deionized water was distilled in glass before use. DMS0 and THF were purified as previously described. Tris(hydroxymethyl )aminomethane (Tris) was obtained from Fisher Chemical Co. and was used without further purification. Kinetic measurements were carried out under two sets of conditions: Method A for the catalysts imidazole, 50, and 53, and Method B for catalysts 26_, 59, 60, _6_2, 63 and 68. Buffer Solutions In Method A, two stock buffer solutions were prepared, 0.1M Tris

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57 and 0.1M Tris-HCl, both having an ionic strength (y) of 0.1 (KC1). The first solution was prepared by adding 12.114 g (0.100 mol ) of Tris and 7.455 g (0.100 mol ) of KC1 to a 1 L volumetric flask and diluting to the mark with distilled water. Tris-HCl was prepared by adding an ampule of 0.1 N HC1 (Acculute), 12.114 g (0.100 mol) of Tris and 7.455 g (0.100 mol) of KC1 to a 1 L volumetric flask and diluting to the mark with distilled water. These two solutions were combined to give a buffer solution of the desired pH. Thus a 2:1 volume ratio of TrisHCl :Tris gave a pH of 7.86 and a 3:1 ratio of Tris-HCl :Tris gave a pH of 7.68 at 25°C. In Method B, two 80% DMS0:H 2 (v/v) stock solutions were prepared, both 0.02M in Tris or Tris-HCl, y = 0.02 (KC1). The first solution was prepared by adding 1.2114 g (0.010 mol) of Tris, 0.7455 g (0.010 mol) of KC1 , and 100 mL of distilled water to a 500 mL volumetric flask and diluting to the mark with distilled DMS0. The second solution was prepared in the same manner, substituting 100 mL of 0.1N HC1 (aq) for 100 mL of distilled water. Again, the solutions were combined to give buffer solution of the desired pH. Thus, a 4:1 volume ratio of Tris-HCl :Tris gave a pH of 8.9. Substrate Solutions In Method A, a stock solution of PNPA (2.69 x 10~ 3 M) in acetonitrile was used. In Method B, stock solutions of PNPA (1.60 x 10 _3 M) in DMS0 and DNPB (1.60 x 10" 3 M) in THF were employed. Catalyst Solutions In both Methods A and B, catalyst solutions were prepared according to the concentration of functional groups. Due to difficulty in

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58 determining the exact composition of copolymers, it was assumed that the copolymers studied were strictly 1:1 alternating copolymers. The contribution to the molecular weight by endgroups was also neglected in all polymer catalysts. Thus, stock solutions of all copolymer catalysts studied in Method B were -5.33 x 10' 3 N in repeat units dissolved in 0.02M Tris buffer of the desired pH. Kinetic Method The following paragraph describes the kinetic method using the Cary 17-D spectrophotometer. The same procedure was used in conjunction with the Perkin-Elmer 330 spectrophotometer with the exception that each sample cell required a corresponding reference cell. To each of 6 -one cm path length quartz cells was added 3.0 mL of buffer solution via pipet. To 4 of the cuvettes was added 150 ul of catalyst solution via micropipet; to the other 2 cuvettes was added 150 ul of buffer solution. To one of the latter cuvettes was added 50 ul of substrate solvent (CH 3 CN, DMS0, or THF), and it was placed in the reference beam of the spectrophotometer. The remaining 5 cuvettes were placed in the sample compartment to equilibrate thermally. The sample cuvettes were then each charged with 50 ul of substrate solution, agitated by inverting the sample holder, and replaced in the sample compartment. The release of p-nitrophenolate ion (Method A 400 nm, Method B 416 nm) or 2,4-dinitrophenolate ion (Method B 370 nm) was observed at constant wavelength at constant time intervals. The reaction was followed for at least 10 half-lives as judged by the constancy of the absorbance readings (A^). A plot of In (A^-A.) vs time (t) was constructed, and the negative slope of the best

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59 straight line as determined by the least squares program of a Texas Instruments TI-55-II calculator gave the desired rate constants ^meas^' As k meas is the sum of the catal y zed ( k b s ) and uncatalyzed (k b 1 ank ) rate constants, it was necessary to subtract k., , from k meas t0 obtain k b s ' Furthermore, the second-order rate constant U cat ) was calculated from the relation k = k . /[catalyst]. 40 In the case of slow reactions where A^ was not obtained in a reasonable time, k meas was determined by the method of Kezdy and Swinbourne, which is described in a monograph by Espenson.

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CHAPTER III RESULTS AND DISCUSSION As was stated in Chapter I, alternating copolymers containing pendant groups which would exhibit cooperative behavior in the hydrolysis of an ester substrate were sought. It was decided to utilize substituted vinyl ether and maleimide monomer pairs in order to achieve the desired alternation of pendant functional groups, as this combination of monomers is known to give regularly alternating copolymers under free-radical initiation conditions. 12 The selection of catalytically active functional groups was made possible by the work of Kunitake et al . ' In these studies, it was shown that the hydroxamic acid group is an excellent acylation catalyst for activated ester substrates. However, decomposition of an acylhydroxamate is a slow process. In order to obtain a useful catalyst, i.e., one with efficient turnover of the catalytic group, the deacylation rate must be comparable to the acylation rate. Kunitake and Okahata 6 found that introduction of an imidazole group into the polymer will accelerate the deacylation process. It was concluded that the imidazole group assists deacylation of the acylhydroxamate intermediate either by acting as a general base or as a nucleophilic catalyst as depicted below. 60

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61 H I Ph N OCCH, II 3 : V> y

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62 Imidazole --Maleimides Our initial attempt to prepare an imidazole maleimide is outlined schematically below. /r-N 9 HNO. H 2 S0 4 2 N o -H 2 H 39 HN i H 2 N 47 Imidazole was nitrated via a literature procedure to afford 4nitroimidazole (39). We envisioned obtaining the desired N-(4-imidazolyl ) maleimide via reaction of 4-aminoimidazole with maleic anhydride ( 47 ) followed by dehydration of the resulting maleamic acid. This attempt was thwarted by the inability to obtain 4-aminoimidazole from reduction of 39. Indeed, 4-aminoimidazole is very unstable and has been isolated only as dihydrochloride and sesquipicrate salts. Our attempts to convert 39 to 4-aminoimidazole are outlined in Table II. In lieu of 4-aminoimidazole, the reactions of histamine (20) and 2-aminothiazole with maleic anhydride were carried out. Although the maleamic acids were obtained in reasonable yield, attempts to effect

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63 TABLE II Hydrogenation of 4-Nitroimidazole (39) Reaction Conditions Work Up Comments H ? /5% Pd on C c DMSO/1 atm. H ? /10% Pd on C c DMS0/-4 atm. Fe/HCl 47 benzene 3% Na(Hg) 48 methanol DMSO solution diluted with ether, treated with anhy. HC1 DMSO solution diluted with benzene, treated with anhy. HC1 benzene solution treated with anhy. HC1 added Hg(0Ac) 9 46 black tar obtained black tar obtained black tar obtained gray solid obtained dehydration to the corresponding maleimides by the method of Searle were unsuccessful . 49 20 86% H 2 N—/ !! + 47 72%

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64 Another strategy to synthesize N-[2-(4-imidazolyl )ethyl]malei mide is outlined below. Reaction of the furan-maleic anhydride Diels-Alder adduct (_8) with 20 afforded compound 24 in good yield. Dehydration of this succinamic acid derivative was also unsuccessful using the Ac 2 0/NaOAc 49 and N,Ndicyclohexylcarbodiimide (DCC)/DMF 50 procedures. Hydroxamic Acid --Maleimides The simplest hydroxamic acid --maleimide is N-hydroxymaleimide (14). The acidity of hydroxamic acids is comparable to the acidity of 51 carboxylic acids; thus, one would expect hydroxamic acid groups incorporated into a polymer to be significantly ionized in neutral or basic media. As N-hydroxysuccinimide has a pka of -6.0, it was believed copolymerization of 14 would fulfill the hydroxamic acid requirement.

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65 53 Ivanov et al . reported the synthesis of _14, and we attempted to duplicate this synthesis as outlined below: NH 2 0H 47 P 2°5 OH NHOH ^^0 5 17 i OH 14 O^w^N-OH 66 Treatment of maleic anhydride (47) with hydroxyl amine afforded N-hydroxymaleamic acid (J7) in 60% yield. We attempted dehydration of 17 using the Ac 2 0/NaOAc 49 and P^/DMF 50 methods, but were unable to isolate 14. Narita et al. 50 had also studied the dehydration of 17 using the following reagents: P^, S0C1 2 , Ac 2 0, p-toluenesulfonic acid, DCC, and acetyl chloride in pyridine. Reaction of 17 with P o c in DMF gave N-hydroxyisomaleimide (66) and not 14 as reported by Ivanov et al. Neither _14 or 66 was obtained by Narita et al. using the other above mentioned dehydration reagents. In another publication by Narita et al . was described the synthesis of N-acetoxymaleimide (11). We felt this monomer would better suit our needs than U itself. It has been observed by Kunitake 43 et al. that polymerization of monomers containing unprotected hydroxamic acid groups is difficult, because the hydroxamic acid group is tautomeric with the nitrone structure, and nitrones are efficient free-radical trapping agents.

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66 OH II / -C-N \ R hydroxamic acid OH ,0 I / -C=N \ R nitrone Therefore, it seemed advisable to use a maleimide containing a protected hydroxamic acid group for polymerizations. Protected maleimide (11) was synthesized via the steps outlined below. The yields indicated are those obtained in this laboratory. \ // 47 Ac 2 1% •OH 65% A 25 mm 82% N I OAc 11 The reverse Diels-Alder reaction of N-substituted maleimide adducts of furan is a powerful method for synthesis of N-substituted maleimides which cannot be obtained from the direct dehydration of the corresponding maleamic acids. Indeed, isomaleimide formation was not a side reaction in this synthesis.

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67 The preparation of N-hydroxymaleimide (14) itself was described in two publications by Akiyama et al . ' This synthesis also employed the furan-maleic anhydride Diels-Alder adduct as a means to obtain maleimide (13), the methanolysis of which gave 14. The reaction scheme along with yields obtained in this laboratory is outlined below. -OH 43% 0OCOC1 DMF, Et 3 N MeOH bromobenzene 160°C OCOPh II 825 13 Carboxylic Acid --Maleimides The carboxylic acid group has been incorporated into synzymes 55,56 and also plays a key role in the "charge-relay system" of the natural 57 enzyme chymotrypsin. We attempted the synthesis of carboxylic acid containing maleimide monomers for two reasons: evaluation of bifunctional synzymes containing the carboxylic acid residue, and conversion of the carboxylic acid group via its N-hydroxysuccinimide ester to a hydroxamic acid group.

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68 The direct dehydration of maleanilic acids 22 and 23 were unsuccessfully carried out using the following reagents: Ac-O/NaOAc, 49 50 59 DCC/DMF,^ DCC/CH 2 C1 2 , J:7 and refluxing xylene. 60 On the other hand, maleanilic acid 15 was cleanly dehydrated to maleimide 16 in 83% yield using AcpO/NaOAc. 0M NH 0=/ \=0 CH 2 C0 2 H 23 Clearly, the presence of the second carboxyl group in 22 and 23^ is in some way responsible for the inability to effect dehydration. Other workers have reported on the inability to dehydrate amino acidmaleamic acids, and the synthesis of maleoylamino acids by modification of maleimide itself has only recently been reported. ' 62 Using this former procedure, N-carbethoxymaleimide (18) was synthesized in 44% yield. ClC0 2 Et Et 0, 0°C C0 2 Et 18

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69 Imidazole -Vinyl Ethers Although imidazole substituted vinyl ethers have not been reported in the literature, we were able to synthesize these compounds in some cases via modification of standard procedures. Our first attempt involved the vinyl transetherification reaction as reported 63 by Watanabe and Conlon. Thus, 2-benzimidazole methanol was treated with an excess of ethyl vinyl ether or n-butyl vinyl ether at reflux in the presence of a catalytic amount of mercuric acetate. H NMR analysis of the reaction mixtures (upon removal of excess vinyl ether) indicated that no reaction had taken place. A possible explanation for the failure of the desired reaction to work was the observation that 2-benzimidazole methanol was largely insoluble in both ethyl vinyl ether and n-butyl vinyl ether. A different approach to this class of compound was more fruitful. ftN Q H 1) K, THF <^N] , DMSO 28 Alkylation of the potassium salt of imidazole with 2-chloroethyl vinyl ether (CEVE) in DMSO afforded desired N-(g-vinyloxyethyl imidazole (28)

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70 as a colorless oil in 46% yield. Vinyl ether (28) was also synthesized via the sodium salt (NaH) of imidazole, albeit in lower yield (25-30%). Although 28 is a tertiary (N-substituted) imidazole, it was believed that the position of substitution would not significantly hinder this compound's ability to catalyze deacylation of the acylhydroxamate in42 termediate in esterolysis reactions. A 4(5)-substituted imidazole --vinyl ether, 3-vinyloxyethyl (imidazol-4ylmethyl )pi peri dim* urn chloride (30), was synthesized, and its ability to copolymerize with maleimide (16) was studied. MeOH 31 29 Reaction of N-(g-vinyloxyethyl )piperidine ( 29 ) and 4-(chloromethyl )imidazole hydrochloride ( 31 ) gave 30 in yields of 70-80%. Vinyl ether 30 proved very difficult to purify, requiring repeated treatment with ^COo in methanol and precipitation into ethyl ether to remove excess 29 as its free base. Furthermore, 30 was isolated as a gummy hygroscopic solid, and attempts to isolate 30 as its hydrochloride salt resulted in rapid hydrolysis of the vinyl ether group. Vinyl ether 30 was consequently used for copolymerization studies in free base form. Despite prolonged drying in vacuo, a major contaminant in 30 was ethyl ether as determined from H NMR.

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71 Another attempt at preparation of a 4(5)-substituted imidazolevinyl ether is outlined below. ^r 1) Mg, THF 2) 31 The covalently bound chlorine atom in 31 is extremely labile to nucleo29 philes as reported by Turner et al . It was postulated that vinyl ether 67 could be obtained by slowly adding 31 to a solution of 2chloroethylmagnesium chloride. The free base of 31 is not stable, presumably due to self-condensation, which necessitated the use of 31. However, CEVE reacted with Mg turnings in THF to give an insoluble Grignard reagent. Addition of 31 resulted in no 67 being formed. Other Imidazole Monomers A search for other imidazole containing monomers which might alternately copolymerize with N-substituted maleimides was conducted. Convinced that the reaction of a Grignard reagent with 31 as described above should work, the reaction of vinylmagnesium bromide with 31 afforded 4-allylimidazole (38) in 45% yield. <^ Br 1) Mg, THF 2 31

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72 This compound had previously been synthesized and characterized by 33 Begg etal. from the pyrolysis of N-allyl imidazole, giving approximately equal amounts of 2and 4-allyl imidazole. Our synthesis thus represents a new and regiospecific method of obtaining 38. In view of the report that allylphenols and N-substituted maleimides copolymerize in alternate fashion, copolymerization studies with 38 were carried out. It was postulated that N-substituted maleimides might also alternately copolymerize with vinyloxycarbonyl-substituted imidazoles, due to similarities in structure between vinyl ethers, vinyl esters, and vinyl carbamates. An empirical comparison of monomer reactivities can be found in the Q-e scheme introduced by Alfrey and Price. The e value, which is a measure of monomer polarity, is positive for electron-deficient olefins such as N-phenylmaleimide (e = +3.24) and negative for electron-rich olefins such as CEVE (e = -1.58), vinyl acetate (e = -0.88), and vinyl N,N-diethylcarbamate (e = -1.10). 65 The reaction of histamine (20) and vinyl chloroformate (V0C-C1) was therefore studied. The reaction of 20 and V0C-C1 was carried out in organic solvents in the presence of an organic base over a range of temperatures. V0C-C1 solvent, R~N -^Ah-z^O ^ -43° -> 15°C * ^^0^ >|H / V.-^ 6-38% 37

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73 In each case, the major isolable product was a diacylated histamine as evidenced by mass spectrometry (M = 251), H NMR (presence 13 of 2 ABX patterns), and C NMR (11 resonances). In the IR spectrum, carbonyl stretching frequencies were observed at 1775 and 1735 cm" . N , 66 T There are three sites on 20 which might be acylated, N , N , and — a it Difficulty was encountered in determining the sites of substitution. Structure 2Z was tentatively assigned as the N a , N T isomer, although the N a , N 71 and N a , N a structures cannot be ruled out. The IR carbonyl stretching frequencies were especially disturbing in view of the carbonyl stretch (1710 cm ) observed for the monoacylated histamine (35) In Table III is reported the conditions and yields obtained in the reaction of 20 with V0C-C1. TABLE III Acylation of Histamine (20) with V0C-C1 20 (equiv) V0C-C1 (equiv) Solvent Base (equiv) T (°C) % Yield 37 a 1.0

PAGE 84

74 When the reaction of 20 and V0C-C1 was carried out under aqueous conditions, the monoacylated histamine 35_ was obtained in low yield. .0 3.0 equiv. NaHCO20-2HC1 H 2 0-dioxane V0C-C1, 0°C 2% Evidence for structure assignment is based on mass spectrometry (M = 1 13 181), H NMR (broad one proton signals at 5.67 and 9.19 ppm) , and C NMR (8 resonances). When _35 was heated above its melting point, a reaction involving displacement of a vinyloxy group took place. 35 — — ' '" Q 2 S 2 H ™ II H 3 s P A 36 zapotidine This compound was assigned structure 36_ on the basis of mass spectro+ 1 13 metry (M = 137), H NMR (loss of vinyl signals), and C NMR (6 resonances). Furthermore, H-2 (the proton flanked by both nitrogen atoms of the imidazole ring) appears further downfield (8.04 ppm) than usual. Comparison with the H NMR spectrum of zapotidine (H-2 = 8.42 ppm) confirms that the downfield resonance of H-2 can be attributed to the deshielding effect of the carbonyl group. No copolymerization studies were conducted with ^35 due to difficulties in obtaining sufficient quantities to work with. It was also suspected that 35_ rearranged to 36 while being chromatographed on silica gel.

PAGE 85

75 Copolymer! zati on of Maleimides with N-(B-Vinyloxyethyl )imidazole (28) Addition of 28 to a CFLClp solution of 11_ resulted in the immediate appearance of a blood-red color which intensified with time. No color change occurred when CEVE was added to a solution of _U. The red color was also apparent in solutions of N-vinylimidazole (46)-_U and N-methyl imidazole --U.. suggesting that the imidazole group was responsible for the red coloration. After appreciable reaction times, the red solutions were precipitated into hexanes or ether-giving palered solids in each case. Evaporation of the filtrate in vacuo gave an oil whose H NMR spectrum revealed a preponderance of N-substituted imidazole over 11. The red solids appeared to be the same substance as judged from their IR spectra (1820, 1790, 1740, 1225, 1160 cm -1 ) and appeared to be the homopolymer of jU. The belief that N-substituted imidazoles were catalyzing homopolymerization of _U was demonstrated by carrying out the reaction using 0.5 mol% of 28. OAc /=\ 0.005 eguiv. 28, AcQ , , , m ^3 0CCH. II 11 65 Further insight as to the structure of 65^ was gained by determining the molecular weight by VP0 (M = 488). This information revealed that 65 was most likely a trimer of 11.

PAGE 86

76 A search of the literature revealed that this reaction had been reported previously, and the major product was a maleimide cyclotrimer. Wagner-Jauregg and Ahmed invoked a zwitterionic mechanism to account for the observed product. Ox R Furthermore, in addition to the desired Michael adduct, 1-25% of maleimide cyclotrimer was formed when imidazole was reacted with N-substituted maleimides in stoichiometric amounts 68

PAGE 87

77 «? D^s^C maleimide + cyclotrimer Although this information was disconcerting as far as our copolymerization strategy was concerned, we nevertheless attempted the copolymerization of ri and 28 using AIBN as initiator. Not surprizingly, only homopolymers of Y\_ were obtained. Direct copolymerization of maleimides _13 and H with 28 were also unsuccessful. Recognizing that the cyclotrimerization reaction was responsible for the inability to obtain alternating copolymer, ways were sought to circumvent this side reaction. It was reasoned that reaction of 2_8 with a Lewis acid would effectively retard the imidazole residue's ability to catalyze cyclotrimerization. ^\0 .N^^N: 28 PG -PG ! *
PAGE 88

78 The ideal protecting group (PG) would coordinate strongly enough with the imidazole moiety to preclude cyclotrimerization yet be easily removed following copolymerization. The hydrochloride salt of 28 might afford adequate protection, however when 28^ was treated with anhydrous HC1 in ether or THF solution, oligomerization of 28 occurred with concomitant cleavage of the vinyl ether. 28 anhyd. HC1 THF or Et 2 sF OH or CI Reaction of 28 with chlorotrimethylsilane (Me.SiCl) in THF might also be expected to provide protection. Me^SiCl equivalent of Me.SiCl in THF in a polymerization tube under N ? In these experiments, either 28 or 46 was allowed to react with 1.0 A solution of _U or 1^3 and AIBN in THF was subsequently added. The appearance of a pink color probably indicated that the N-Si bond was too labile to afford adequate protection. Homopolymers of _H and 13 were obtained in low yields.

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79 Vinyl ether 28 and maleimide _U were successfully copolymerized when 28 was pretreated with 1.0 equivalent of aqueous HC1 . Maleimide 11 was added in acetone or THF solution to give a homogeneous mixture. Polymerization was initiated via redox conditions, K^Og and an Fe(II) salt. -20% ?s + 11 1.0 equiv. HC1 (aq) — — H 2 0-THF K 2 S 2 g ,Fe(NH 4 ) 2 (S0 4 ) 2 -6H 2 30°C, 90 h The copolymer was purified by precipitating the reaction mixture into acetone (to remove maleimide homopolymer) , redissolving the oily precipitate in aqueous HC1 and dialyzing this solution against deionized water. Copolymer 53 precipitated from solution during dialysis. The IR spectrum of _53 indicated the presence of both monomers, carbonyl stretching frequencies at 1780 and 1705 cm (indicating that the Nacetoxy group had been hydrolyzed) and C-0-C ether stretch at 1105 cm . The carbonyl absorbances for 53 are identical to those reported for N-hydroxymaleimide -styrene copolymer. Evidence for alterna13 tion can be found in C NMR spectrum of 53 (Figure 1). In the carbonyl region appear 3 peaks in area ratios of -2:1:1. This is consistent with an alternating copolymer with a homogeneous sequence distribution whose stereochemistry at the succinimide unit is exclusively cis or trans and whose carbonyls can "see" relative stereochemistry two bonds distant. Carbon 10 can be assigned as the upfield doublet

PAGE 90

80

PAGE 91

81 reflecting random relative stereochemistry between C-2andC-3. Carbon 11 then appears as a singlet as a result of its inability to "see" relative stereochemistry three bonds distant. The carbonyl region of 53 is analogous to the carbonyl region of N-phenylmaleimide --2-chloro 1? ethyl vinyl ether alternating copolymer as reported by Olson. Indeed, a more complete explanation of this reasoning can be found in 12 this work. The assignment given carbonyl carbons 10 and 11 can also be rationalized by empirical chemical shift parameters first reported by Grant and Paul. Substituents other than protons which are situated a or B to a carbon of interest cause a downfield shift (~9 ppm) relative to a similar compound without substitution. Substituents other than protons which are situated y to a carbon of interest cause an upfield shift (~2 ppm). Examination of the copolymer structure reveals that carbons 10 and 11 have equal numbers of a and g substituents. Carbonyl 10, however, has an addition y substituent by virtue of branching at C-2. Therefore, C-10 should appear further upfield than C-ll. The resonances between 120 and 140 ppm were assigned to the carbons of the imidazole ring. The signal appearing furthest downfield was assigned to C-9, while no distinction could be made between C-7 and C-8. The resonances between 70 and 80 ppm are typical for carbon atoms alpha to an oxygen atom. Differentiation between C-2 and C-5 could be made after examination of an off-resonance spectrum (Figure 2). The signal furthest upfield appeared as a triplet (C-5) and the downfield

PAGE 92

82

PAGE 93

83 signal as a doublet (C-2). Carbon-6 also appeared as a triplet in the 13 off-resonance C spectrum. Further evidence for alternation can be obtained from the chemical shifts of the succinimide backbone carbons, C-3 and C-4. In the 13 C NMR spectrum of N-hydroxymaleimide homopolymer (50), the backbone carbons appear as a broad singlet centered at -42 ppm. In copolymer 53 the succinimide backbone carbons appear as two signals at -39 and -48 ppm. Carbon-4 was assigned to the upfield signal on the basis of having one additional y substituent vs. C-3. In addition, C-3 has one additional B substituent than does C-4. The broad hump appearing between C-3 and C-4 at -42 ppm is probably attributable to the methine carbons of homomaleimide sequences. The methylene backbone carbon atom (C-l) was assigned to the signal appearing furthest upfield. Copolymer ^3 possesses very interesting solubility characteristics. As isolated, _53 is virtually insoluble in all common organic solvents, although it will dissolve in DMSO at elevated temperatures. Interestingly, 53 is water soluble at pH <3.6 and pH >7.1 but insoluble between these limits. This solution behavior led us to believe that 53 is a polyampholyte.

PAGE 94

84 Solubility is attained when the copolymer is protonated or deprotonated giving rise to net positive or negative charges. Under these conditions, 52 might be expected to behave as a polyelectrolyte. At the isoelectric point, however, the attraction between oppositely charged side chains should result in tight coiling, hence a lack of solubility. In this case, an increase in the ionic strength of the medium should lead to expansion of the chains and impart water solubility. Such behavior has been noted for polyvinyl imidazolium sulphobetaine) (PVISB) 72 by Salamone et al . The solubility of 53 in various salt solutions is shown in Table IV. It can be seen that certain salts are more effective than others with respect to dissolving power. Interestingly, both sat. LiCl and sat. LiBr completely dissolve 53, while 5.0 M LiCl only partially dissolves 53. It is also not clear why 53 is soluble in sat. Nal, partially soluble in sat. NaCl , and apparently insoluble in sat. NaBr. TABLE IV Solubility of 53 in Salt Solutions Anion CI" Br" r RF ~ Cation u tir l Bh 4 i i + sat + +4. 1 5.0M P sat * Na + sat. P sat. »$. J K sat. P sat. sat. sat. = saturated solution + = soluble = insoluble P = partially soluble

PAGE 95

85 Salamone et al . found that large cations, e.g. K , and large anions, e.g. CIO. , were more effective solubilizing ions than were smaller ions. Minimum salt concentrations were of the order of 0.03-0.52M for PVISB, while saturated salt solutions were necessary to impart solubility to 53 . Determination of the molecular weight of 53 proved difficult, and the results were ambiguous. VPO analysis in DMSO at 100°C gave M = 500 g/mol . It is believed that this number represents a minimum value as 53 was observed to decompose under similar conditions in the NMR probe. As VPO is a colligative technique, the presence of decomposition fragments would result in a lower M than expected. A maximum molecular weight value was calculated from end group analysis (elemental analysis for S). Presumably the initiating species in the redox 73 system employed is the sulfate radical anion. S 2°8 2 " + Fe+ ^— * S0 4 2 " + S0 4 T + Fe+3 Assuming the incorporation of one sulfate group per polymer chain, from calculation of an empirical formula a molecular weight of = 6000 g/mol was derived. The intrinsic viscosity [n] of 53 was determined in 0.1N HC1 at 30.0°C to be 0.112 dL/g. Although this value cannot be directly related to molecular weight, it is an indication of the hydrodynamic volume of 53. Of course the size of the polymer chains should vary with the pH of the medium, and one would expect a change in [n] dependent on the degree of ionization of imidazole groups.

PAGE 96

86 Gel permeation chromatography of 53 revealed two components in a 3:1 area ratio, the larger component having the shorter retention volume. The presence of two components precluded accurate molecular weight determination, as the individual viscosities could not be determined independently. It was suspected that the minor component was attributable to N-hydroxymaleimide homopolymer (50), which we were unable to separate from 5_3. In another set of experiments, 28 was mixed with ZnCl ? in THF before addition of AIBN and 11. In this case, a white-THF insoluble powder was obtained after only a few hours at 60°C. The IR spectrum of this material indicated that both 11 and 28_ had been incorporated as evidenced by carbonyl stretching frequencies at 1818, 1785 and 1730 cm and C-O-C ether stretch at 1110 and 1095 cm . The incorporation of ZnClp into this material was inferred by elemental analysis for CI (9.22%). Elemental analysis was reasonably consistent with a structure containing two equivalents of 28 and two equivalents of 1_1 per equivalent of ZnCl ? . Reaction of 28 with four equivalents of ZnCK in ethanol gave, after dilution with ether, an 89% yield of 33, mp 78.5-80°C. 28 4.0 equiv. ZnCU EtOH <^\ N— ZnCl, 33 The stoichiometry of this complex was determined from elemental analysis and is consistent with N-alkylimidazole -ZnCl ? complexes studied by Welleman et al 32 On the basis of the structure of 33 and the

PAGE 97

87 elemental analysis data for the ZnClp copolymer, the latter's repeating unit was assigned structure (54). 54 This crosslinked structure accounts for the insolubility of 54 in common organic solvents. However, 54 dissolves in warm DMSO (~60°C), presumably giving a DMSO-ZnCK complex and free copolymer. The [n] of a DMSO solution of 54 at 30.0°C was equal to 0.043 dL/g. Copolymer 54 is also soluble in water at pH >13 (NaOH) and pH <3.5 (HC1).

PAGE 98

88 13 The proton decoupled C NMR spectrum of 54 is shown in Figure 3. 13 Similarities to the C NMR spectrum of 53 (Figure 1) are apparent, and the assignment of carbon atoms is the same as in 53. Two additional peaks one in the carbonyl region and one at -22 ppm can probably be assigned to acetic acid (from hydrolysis of the N-acetoxy group). The resonance at -42 ppm most likely indicates the presence of homomaleimide sequences. Copolymerization of Fumaronitrile (45) and Pi ethyl fumarate (44) With N-(0-Vinyloxyethyl jimidazole (28) In view of the fact that 28 would not cleanly copolymerize with 11 or Y3, it was decided to attempt copolymerization of 28^ with fumaronitrile (45J and diethyl fumarate (44). As both latter monomers are electron deficient, 45 (e = +2.73) 65 and 44 (e = +2.26), 65 it was believed copolymerization with vinyl ether (28) might afford alternating copolymers. Indeed, alternating copolymers have been obtained from 75 65 copolymerization of both 45_ and 44 with N-vinylcarbazole (e = -1.29) . It was envisioned that hydroxamic acid groups could be introduced following copolymerization via transformation of the nitrile and ester groups. Copolymerizations of 28 with 44 and 45 were carried out in solution at 60°C using AIBN as initiator. Low yields of low molecular weight copolymers were obtained in each case. The H NMR spectrum of 56 indicated that the copolymer was rich in diethyl fumarate (-2.3:1) as determined by comparing the integration of methyl protons to imidazole protons. These data are supported by elemental analysis for nitrogen, the value obtained being -2.8% lower than expected for a 1:1

PAGE 99

39

PAGE 100

90 28 + 44 28 + 45 acetone AIBN 60°C, 90 h CH 2 C1 2 AIBN 60°C, 44 h C0 2 Et copolymer. Copolymer 55 was suspected of being rich in fumaronitrile on the basis of nitrogen analysis, found to be -2.7% higher than expected for a 1:1 alternating copolymer. Since alternating copolymers were not obtained in either case, no attempt was made to transform either the nitrile or ester group to a hydroxamic acid group. Copolymerization of Maleimide (16) With 3-Viny1ox.yethy1(imidazol-4,y1meth.yl )piperidinium Chloride (30) After it had been established that copolymer (53) was not an efficient catalyst, new catalysts were sought. It was proposed that a better catalyst could be obtained by changing the nature of the hydroxamic acid group and by varying the position of substitution on the imidazole ring. Our strategy involved copolymerizing a 4(5)imidazole-substituted vinyl ether with an ester-maleimide and converting the ester group to a hydroxamic acid group following the copolymerization step.

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91 o^,Ao C0 2 R C0 2 R O NHROH I CONROH To this end, maleimide Q6) and vinyl ether (30) were synthesized and their copolymerization attempted. Because of the extreme rapidity with which 30 hydrolyzed under acidic conditions, no copolymer was formed under the redox conditions under which U_ and 28 were successfully copolymerized. The hydrophobic nature of _16 necessitated the use of a water miscible organic solvent to obtain a homogeneous reaction mixture. Addition of an organic solvent to an acidic-aqueous solution of 30 resulted in an immediate exothermic reaction probably indicative of hydrolysis of the vinyl ether group. Therefore, it was believed that complete hydrolysis took place before any copolymerization could occur. When _16 and 30 were allowed to react in organic solvents using AIBN as initiator (no acid present), only homopolymers of _16 were obtained. In Table V is summarized our attempts to copolymerize 16 and 30.

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92 CD C "O •ia> ca > 4-> ra -Q CD O i— o 0) CT3T3 O (T3 rt3 CD a; rCD 3 sE cd >,T3 -E i— CD +-> O SCD Q. CD O > — O O >> CD -t•rCD ai •ii. >> CD -c >, Oli— •io rO

PAGE 103

93 Copolymerization of Maleimide (11) with 4-Allyl imidazole (38) Copolymerization of 38 and 11. was attempted with and without acid protection of 38. In only one case was a copolymer obtained (as evi1 3 denced by the presence of imidazole and carbonyl resonances in the C NMR spectrum) in low yield. It could not be determined whether the copolymer was random or alternating in structure. In any case, the IR spectrum indicated that the M-acetoxy group had been hydrolyzed to the N-hydroxy group (1780, 1710 cm" ). Reaction conditions and a summary of results are given in Table VI. Homopolymers In order to more fully understand the catalytic activity exhibited by copolymer S3, we desired the homopolymers of 14 and 28 for comparison purposes. I OH 50 Poly(N-hydroxymaleimide) (50) was synthesized via two routes as shown below. Polymerization of _U with AIBN in CH„C1» afforded homopolymer (48) in 80% conversion, whose molecular weight was determined by VP0 (M = 3850 g/mol). Treatment of 48 with hydroxyl amine gave 50. Homopolymer (_50) exhibited carbonyl stretching frequencies of 1785 and -1 13 1770 cm and broad resonances in the C NMR spectrum centered at 42.0 and 172.7 ppm.

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94

PAGE 105

AIBN — CHgCl 2 AIBN 1 ? — acetone 95 N' I OAc 48 N' I OCO0 II 49 NH„OH MeOH OH 50 Homopolymer (50) was more conveniently prepared from the methanolysis of 49 in 88% yield. Polymerization of 13 with AIBN in acetone 13 afforded 4J9 in 87% conversion. The proton decoupled C NMR spectrum of 50 is shown in Figure 4. Homopolymerization of 2S was not as straightforward. Although the polymerization of vinyl ethers with cationic initiators is well documented, we were unable to obtain 52 in high conversion or in moderate molecular weight. The low yields obtained under cationic conditions might be due to the imidazole's ability to coordinate with the initiator, thereby rendering the latter ineffective. Not surprisingly, 52^ was not obtained by use of free-radical initiators. Table VII contains a summary of initiators, reaction conditions and results.

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96

PAGE 107

o en c 1O 97 re 4C O •!E T3 Si— CD HI -M >>-o 3 Qo re <— sT3

PAGE 108

98 N-(4-Carbethoxyphenyl)maleimide (16_) was homopolymerized with AIBN in DMF to give 51 in 61% conversion. Surprisingly, insoluble polymers resulted when the polymerization was carried out with AIBN in Ch^Clp^ or acetone. Reaction of 51 with hydroxylamine resulted in only partial conversion of ester to hydroxamic acid groups as judged by elemental analysis for nitrogen. 16 AIBN a rN , r N^"0 2 C0 2 Et 51 Copolymerization of Propenyl phenols With Maleic Anhydride (47) and N-Ethylmaleimide (43) In light of the study by Overberger et al . (p. 6), which demonstrated cooperative interactions between imidazole and phenol groups, it was decided to synthesize and evaluate alternating copolymers containing these functional groups. As considerable difficulty was encountered with the direct polymerization of imidazole containing monomers, the imidazole group was introduced into pre-existing alternating copolymers. op It was reported by Iwabuchi et al . that a 1:1 alternating copolymer resulted from copolymerization of isoeugenol ( 41 ) and maleic

PAGE 109

99 anhydride (47). This reaction was repeated in this laboratory and gave copolymer _57 in 62% conversion. Treatment of 57 with histamine ( 20 ) in refluxing DMF gave a quantitative yield of copolymer j>9 containing both phenol and imidazole functionalities. + 47 AIBN acetone, 60° 72 h ^?°di * OMe 20 DMF, 150°C 59 In order to show that ^9 contained succinimide and not succinamic acid units, model compounds 25 and 26^ were synthesized. + 20 acetone, H 2 H_ OH

PAGE 110

100 + 20 DMF 150° Imide ( 26 ) displayed carbonyl stretching frequencies at 1765 and 1690 cm which were in agreement with those of copolymer 5_9. Compound 25_ displayed IR absorptions at 1635 and 1610 cm . Copolymers 58 and 6£ were synthesized in a similar manner, as were 61 and 62. 47 + 40 AIBN — acetone o 60°, 44 h 58 Xj-° H ?50° 0< >0 (^ J 60 AIBN 1Z. + 42 acetone 60°, 48 h

PAGE 111

101 It was desired that either 59^ or 60 would exhibit cooperativity in the hydrolysis of an ester substrate, while 62 would exhibit catalysis by the imidazole group only. Copolymers 62 and 64_ were synthesized to demonstrate catalysis by the phenol group only. 43 + 41 AIBN acetone 60°, 38 h 43 + 40 AIBN acetone 60°, 38 h ^^O Et 63 64 Although we were unable to prove spectroscopically the alternating nature of these copolymers, other observations point toward a nearly alternating structure. Mixing 47 or 43_ with 40, 41, and 42^ produces a yellow color, probably indicative of a charge-transfer com11 82 plex. Iwabuchi et al. have shown that 41 and 47 form a 1:1 copolymer regardless of monomer feed ratios. Elemental analysis of copolymer 61_ gives excellent agreement for a 1:1 copolymer, although the others do not. Finally, neither propenyl phenols nor 47^ homopolymerize under the copolymerization conditions employed.

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102 A list of some properties of copolymers 57 + 64 are presented in Table VIII. TABLE VIII Properties of Copolymers 57 * 64 Copolymer

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103

PAGE 114

104 any case, the rate enhancement in the presence of _50 is small and may not be statistically important. The catalytic activity of copolymer 53^ was found to be significantly higher than 50 yet much lower than monomeric imidazole. Due to the lack of catalytic activity shown by 50, it can be concluded that neutral imidazole residues are responsible for the rate enhancement exhibited by copolymer _53. Once again, a rate enhancement was observed at higher pH, which might be related to the degree of ionization of protonated imidazole groups. Alternatively, an increase in pH might expand the polymer chains, allowing easier access of the substrate to the reaction site. Additional kinetic studies were not carried out on this system due to the poor catalysis exhibited by _5_3, the knowledge that jh3 was impure, the failure to obtain homopolymer 5^2, and the apparent lack of cooperative behavior between hydroxamic acid and imidazole groups in 53 . Kinetic Studies With Copolymers 59, 60, 62, 63 and 68 and Model Compound 26 Pseudo first-order kinetics were measured using copolymer catalysts 5_9, 60, 62 and 63 as previously described (Method B pp. 56-59). The water insolubility of these copolymers necessitated the use of an 80% DMS0:H 2 (V/V) medium. Copolymer 64 was insoluble in this solvent system and therefore was not studied as a catalyst. PNPA was initially used as substrate, however its hydrolysis proceeded too slowly to obtain rate constants in a reasonable time. The more reactive substrate DNPB was subsequently used. The results obtained with these copolymer catalysts are presented in Table X and shown graphically in Figure 5.

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105 TABLE X Esterolysis a of DNPB with 26, 59, 60, 62, 63 and 68 Catalyst PH obs (min -1 ) k cat o-morW 1 ; 26 59 60 62 63 68 blank 26 59 60 62 63 68 blank 26 59 60 62 63 68 blank 8.4 8.9 9.5 4.46 x

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106 Table X Continued Catalyst pH k . (min" ) k , (l-mol~ min" ) 26 10.0 59 60 62 63 68 blank 5.35 x

PAGE 117

10 7 22.0 — 21.0 20.0 — 19.0 — £ 18.0 17.016.0 15.0 — 14.0 13.0 i i r i 1 1 r 8.0 9.0 PH X Figure 5. pH-rate profile for the esterolysis of DNPB using 59_<3 > 60 A, and 62 Q as catalysts.

PAGE 118

108 It can be seen that copolymer J53 exhibited little or no catalytic activity toward hydrolysis of DNPB, which implies that the phenol group or phenolate ion is catalytically inactive. All of the imidazole containing copolymers (59, 60 and 62) catalyze the esterolysis of DNPB at about the same rate. No cooperative interactions between imidazole and phenol groups were observed by comparison of the rates for 59 and 60 vs 62 . Indeed, copolymer 62^ was the most efficient catalyst in this group. The differences in the rate constants for 5J3, i50 and 62 are most likely the result of unequal concentrations of imidazole groups. As can be seen in Figure 5, copolymers _59, 6j3 and 62 display a bell -shaped pH-rate profile. Such behavior is often interpreted as a result of simultaneous participation by a general acid (BH ) and a weak base (nucleophil ic or general). The concentration of BH would decrease with increasing pH which would account for the decrease ink . ca x. at pH = 10.0. A reasonable candidate for BH is the imidazolium ion. This argument is unsatisfactory, however, because of the extreme reactivity of DNPB, i.e., no assistance by a general acid should be required to effect hydrolysis. Also, the pKa of the 4-methyl imidazolium 83 ion is 7.61 which would indicate that the concentration of imidazolium ion in the polymer is yery low in the pH range studied. Without a knowledge of the pKa of the imidazolium ion in the copolymers studied, this latter argument is speculative. Another factor which might account for a bell -shaped pH-rate profile is the conformation of the copolymers in solution. If ring closure following derivatization of the maleic anhydride copolymers with histamine did not proceed quantitatively, a small number of succinamic

PAGE 119

109 acid units would result giving rise to a polyelectrolyte. Alternatively, ring opening might occur under the conditions of the kinetic experiments. To check this latter hypothesis, copolymer 62_ was recovered after standing in buffer solution at pH = 10.0 for 15 days. The IR spectrum of recovered 62 was identical to the spectrum of untreated copolymer, indicating that no ring opening had occurred in buffer solution. Copolymer 62_ did exhibit polyelectrolyte behavior as determined by an increase in n / on dilution (Figure 6). The bell -shaped pHrate profile might then be explained by chain expansion, allowing greater access of DNPB to imidazole residues and chain contraction at higher pH leading to a decrease in observed rate. To test this hypothesis, compound _26 and copolymer 58 were evaluated as catalysts, Table X , Figure 7. H 68 Model compound 26 exhibited a similar bell-shaped pH-rate profile, which gave evidence that this behavior could not be attributed to copolymer conformation.

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110 ill c .92 .90 .88 .86 " .84 .82 .80 .78 .76 .74 .72 .70 .68 .66 1 .64 .62 " .60 .58 .56 .54 0.01 0.02 0.03 0.04 0.05 0.06 C (g/dL) Figure 6. Plot of ti 5P /C vs. C for copolymer 62, 0.02M Tris buffer, u = 0.02 (KC1), pH = 9.5.

PAGE 121

Ill 27 26 25 24 23 E C 22 21 20 19 18 ~ l r 8.2 t i 1 1 r 9.0 1 1 r 10.0 pH Figure 7. pH-rate profile for the esterolysis of DNPB using 260 and &3 A as catalysts.

PAGE 122

112 In view of the small differences in k . with increasing pH, it became evident that the bell-shaped pH-rate profile might not be real. Indeed, there seems to be only a slight dependence of catalytic activity on pH. Therefore, the bell-shape might be the result of error associated with the determination of pH and k , . r obs Conclusion Our inability to observe cooperativity between imidazole -hydroxamic acid and imidazole -phenol groups is surprising in light of results by other workers. Cooperativity might be expected in alternating copolymers only when a precise stereochemical fit can be achieved between substrate and functional groups. Cooperativity reported by other workers in random bifunctional copolymers might be the result of a serendipitous alignment of functional groups as a result of chain conformation. Further work in this area should concentrate on obtaining a precise stereochemical fit between substrate and functional groups. Model compounds might provide the basis for further polymer development. Some parameters which might be modified include: the distance of functional groups from the backbone, the distance of functional groups from each other, the overall hydrophobicity of the polymer, and the nature of the functional groups themselves. One might also imitate natural enzymes by making insoluble but swellable catalysts. Soluble polymers possessing both hydrophobic and hydrophilic regions might be obtained via block copolymerization of appropriate pre-polymers. The synzyme field is full of opportunity we have not yet scratched the surface.

PAGE 123

APPENDIX SELECTED l H AND 13 C NMR SPECTRA

PAGE 124

114

PAGE 125

115

PAGE 126

116 CH -r^ o

PAGE 127

117 +> .— CJ C_> QJ Q

PAGE 128

118

PAGE 129

119 SI
PAGE 130

120 i O) O r— J O X «tf-

PAGE 131

121 i— I CJ

PAGE 132

122 i >> • X o O o so -a c\j I +-> •ra ic >1

PAGE 133

123 Q. B 1/1 >, r-J rH Q

PAGE 134

124

PAGE 135

125

PAGE 136

126

PAGE 137

127
PAGE 138

128 J o

PAGE 139

129

PAGE 140

130 o <—

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134 50. M. Narita, M. Akiyama and M. Okawara, Bull. Chem. Soc. Jp. 44, 437 (1971). ~ 51. S.R. Sandler and W. Karo, "Organic Functional Group Preparations, Vol. Ill," Academic Press, New York, 1971, p. 406. 52. D.E. Ames and T.F. Grey, J. Chem. Soc, 631 (1955). 53. V.S. Ivanov, V.K. Smirnova, A.E. Semenova and T. Yure, J. Org. Chem., USSR 1, 1729 (1965); Chem. Abstr. 64, 586g (1966). 54. M. Akiyama, K. Shimizu and M. Narita, Tet. Lett., 1015 (1976). 55. C.G. Overberger and H. Maki , Macromolecules 3_, 214 (1970). 56. C.G. Overberger and H. Maki, Macromolecules 3_, 220 (1970). 57. D.M. Blow and T.A. Steitz, Ann. Rev. Biochem. 39, 716 (1970). 58. A. Winston and D. Kirchner, Macromolecules _U, 597 (1978). 59. R.J. Cotter, C.K. Sauers and J.M. Whelan, J. Org. Chem. 26, 10 (1961). — 60. L.E. Coleman, J.F. Bork and H. Dunn, Jr., J. Org. Chem. 24, 135 (1959). — 61. F.E. King. J.W. Clark-Lewis, R. Wade and W.A. Swindin, J. Chem. Soc, 873 (1957). 62. G.B. Butler and A. Zampini, J. Macromol . Sci.-Chem. All, 491 (1977). 63. W.H. Watanabe and L.E. Conlon, J. Am. Chem. Soc. _79, 2828 (1957). 64. T. Alfrey, Jr. and C.C. Price, J. Polym. Sci. 2, 101 (1947). 65. R.Z. Greenley, J. Macromol. Sci.-Chem. A14, 427 (1980). 66. J.W. Black and C.R. Ganellin, Experientia 30, 111 (1974). 67. F.B. Stocker, M.W. Fordice, J.K. Larson and J.H. Thorstenson, J. Org. Chem. 31, 2380 (1966). 68. T. Wagner-Jauregg and Q. Ahmed, Helv. Chim. Acta 56, 1406 (1973). 69. T. Wagner-Jauregg and Q. Ahmed, Helv. Chim. Acta 57, 1871 (1974). 70. M. Akiyama, M. Narita and M. Okawara, J. Polym. Sci., Part A-l 7, 1299 (1969).

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135 71. D.M. Grant and E.G. Paul, J. Am. Chem. Soc. 86, 2984 (1964). 72. J.C. Salamone, W. Volksen, A. P. Olson and S.C. Israel, Polymer 19, 1157 (1978). 73. F.W. Billmeyer, Jr., "Textbook of Polymer Science, 2nd Ed.," John Wiley and Sons, Inc., New York, 1971, p. 363. 74. F.A. Cotton and R. Francis, J. Am. Chem. Soc. 82, 2986 (1960). 75. Y. Shi rota, M. Yoshimura, A. Matsumoto and H. Mikawa, Macromolecules 7, 4 (1974). 76. S.R. Sandler and W. Karo, "Polymer Syntheses II," Academic Press, New York, 1977, p. 214. 77. N.D. Field and D.H. Lorenz in "Vinyl and Diene Monomers-Part 1," E.C. Leonard, Ed., Wiley-Interscience, New York, 1970, p. 396. 78. C.E. Schildknecht in "Kirk-Othmer Encyclopedia of Chemical Technology-2nd Ed.," Vol. 21, Wiley-Interscience, New York, 1970, p. 412. 79. C.E. Schildknecht, C.H. Lee and W.E. Maust in "Macromolecular Syntheses, Collective Volume I," J. A. Moore, Ed., John Wiley and Sons, Inc., New York, 1978, p. 113. 80. G. Hardy, K. Nyitrai and F. Cser in "Macromolecular Syntheses, Collective Volume I," J. A. Moore, Ed., John Wiley and Sons, Inc., New York, 1978, p. 669. 81. S.L.N. Seung and R.N. Young, J. Polym. Sci.-Polym. Lett. Ed. 16, 367 (1978). 82. S. Iwabuchi , K. Kojima, T. Nakahira and H. Hosoya, Makromol. Chem. 177 , 1643 (1976). 83. F. Schneider, Z. Physiol. Chem. 338, 131 (1964); Chem. Abstr. 62, 11905 (1965).

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BIOGRAPHICAL SKETCH David Paul Vanderbilt was born on January 18, 1954, in Easton, PA. He was a 1971 graduate of Wilson Boro High School, Easton, PA. The author received the B.S. degree in chemistry from the Pennsylvania State University, University Park, PA, in 1975. Mr. Vanderbilt enrolled in the Graduate School at the University of Florida in September, 1976. He received the M.S. degree in chemistry in August, 1979, under the auspices of Professor Merle A. Battiste. While pursuing M.S. and Ph.D. degrees at U.F., the author served as a teaching and research assistant in the Department of Chemistry. He is a member of the American Chemical Society. 136

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I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. George B. Butler, Chairman Professor of Chemistry I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Merle A. Battiste Professor of Chemistry I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. -'l-r^ i. -C< /-— /~~ ls.Ol~ Thieo E. Hogen-Esch Professor of Chemistry I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Gus J. Palehik Professor of Chemistry

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I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Eugene 7 P. Goldberg Professor of Materials Science"* and Engineering This dissertation was submitted to the Graduate Faculty of the Department of Chemistry in the College of Liberal Arts and Sciences and to the Graduate Council, and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy. December, 1982 Dean for Graduate Studies and Research

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UNIVERSITY OF FLORIDA 3 1262 08553 1654