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Record for a UF thesis. Title & abstract won't display until thesis is accessible after 2012-12-31.

Permanent Link: http://ufdc.ufl.edu/UFE0042629/00001

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Title: Record for a UF thesis. Title & abstract won't display until thesis is accessible after 2012-12-31.
Physical Description: Book
Language: english
Creator: Kovacs, Judit
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
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Electronic Thesis or Dissertation

Notes

Statement of Responsibility: by Judit Kovacs.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Katritzky, Alan R.
Electronic Access: INACCESSIBLE UNTIL 2012-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042629:00001

Permanent Link: http://ufdc.ufl.edu/UFE0042629/00001

Material Information

Title: Record for a UF thesis. Title & abstract won't display until thesis is accessible after 2012-12-31.
Physical Description: Book
Language: english
Creator: Kovacs, Judit
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Statement of Responsibility: by Judit Kovacs.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Katritzky, Alan R.
Electronic Access: INACCESSIBLE UNTIL 2012-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042629:00001


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1 SYNTHESIS OF FUNCTIONALIZED PYRROLO[1,2 B ]PYRIDAZINES AND PYRAZOLO[1,5 A ]PYRIDINES By JUDIT KOVACS A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

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2 2010 Judit Kovacs

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3 To my father, Dr. Peter Kovacs F or his continued love and support

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4 ACKNOWLEDGMENTS I would like to thank my advisor, Prof. Alan R. Katritzky for the opportunity, g reat understanding, and support during this period. I thank c urrent and former group members; especially Dr. C. Dennis Hall, Dr. Levan Khelshvili, Dr. Daniebelle N. Haase Dr. Megumi Yoshioka Tarver, M s. Claudia El Nachef, Ms. Longchuan Huang, and Ms. Kath ryn D. Chinn. Special thanks go to Dr. Ben Smith, Ms Lori Clark, Dr. Tammy Davidson, Ms. Elisabeth Sheppard, Ms. Yaketerina Kovalenko, and Ms. Gwen McCann. France for their val uable suggestions and financial support. I thank my committee members, Prof. Lisa McElwee White, Dr. Ste ph en A. Miller, and Dr. Ion Ghiviriga for their help and support. I also thank to my father Dr. Peter Kovacs, my stepmother Dr. Agota Kovacsne Hovany a nd my family and friends for their support.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF FIGURES ................................ ................................ ................................ .......... 7 LIST OF SCHEMES ................................ ................................ ................................ ........ 8 LIST OF ABBREVIATIONS ................................ ................................ ........................... 10 ABSTRACT ................................ ................................ ................................ ................... 14 CHAPTER 1 GENERAL INTRODUCTION ................................ ................................ .................. 16 1.1 Overview of the Synthesis of Pyrrolo[1,2 b ]pyridazines ................................ 16 1.1.1 Synthesis Starting fro m Pyridazine and Acetylenic Esters .................. 16 1.1.2 The 1,3 dipolar Cycloaddition of Mesoionic Oxazolo[2,3 b ]pyridazines ................................ ................................ ....................... 18 1.2 Overview of the Synthesis of Pyrazolo[1,5 a ]pyridines ................................ ... 19 2 SYNTHESIS OF FUNCTIONALIZED PYRROLO[1,2 B]PYRIDAZINE ................... 22 2.1 Literature Overvi ew ................................ ................................ ........................ 22 2.1.1 Biological Properties of Pyrrolo[1,2 b ]pyridazines ............................... 22 2.1.2 Optical Properties of Pyrrolo[1,2 b ]pyridazines ................................ .... 24 2.2 Results and Discussion ................................ ................................ .................. 26 2.2.1 Retro Synthetic Analysis: Synthesis Plan ................................ ............ 26 2.2.2 The Synthesis of 2 (3 Chloro 6 oxopyridazin 1(6 H ) yl)propanoic Acid 2.14 and 2 (3 (Dimethylamino) 6 oxopyridazin 1(6 H ) yl)propanoic Acid 2.10 ................................ ................................ ......... 28 2.2.3 1,3 Dipolar Cycloadditio n ................................ ................................ .... 29 2.2.4 Attempts to Obtain the Final Target ................................ ..................... 30 2.3 Summary ................................ ................................ ................................ ........ 31 2.4 Experimental Section ................................ ................................ ..................... 32 2.4.1 General Methods ................................ ................................ ................. 32 2.4.2 Preparation of 6 Chloro 2 H pyridazin 3 one 2.15 ................................ 32 2.4.3 Preparation of 6 Chloro N,N dimethylpyridazin 3 amine 2.18 ............. 32 2.4.4 Preparation of 6 (Dimethylamino)pyridazine 3(2 H ) one 2.11 .............. 33 2.4.5 General Procedure for the Preparation of Compounds 2.17 and 2.19 ................................ ................................ ................................ ..... 33 2.4.6 General Procedure for the Preparation of Compounds 2.14 an d 2.10 ................................ ................................ ................................ ..... 34 2.4.7 General Procedure for the Preparation of Compounds 2.13, 2.6, and 2.7 ................................ ................................ ................................ 35

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6 3 SYNTHESIS OF FUNCTIONALIZED PYRAZOLO[1,5-A ]PYRIDINE ...................... 373.1 Literature Overview ........................................................................................ 373.1.1 Biological Properties of Pyrazolo[1,5a ]pyridines ................................. 373.1.2 Pyrazolo[1,5a ]pyridines as Dyeing A gents ......................................... 463.2 Results and Discussion .................................................................................. 482.2.1 Retro Synthetic Anal ysis: Synthesis Plan ............................................ 483.2.2 The Synthesis of the Starting Materials: N-amino-pyridinium 2,4dinitrophenolates 3.31 and 3. 32 .......................................................... 49Substituted pyridi nes 3.33 and 3.34 .................................................... 49N-amino-pyridinium 2,4-dinitrophenolates 3. 31 and 3.32 .................... 503.2.3 1,3-Dipolar Cycloaddit ion .................................................................... 513.2.4 Attempts to Obtain the Final Target ..................................................... 522-Methyl-4-nitropyrazolo[1,5a ]pyridin-5-ol 3.25 .................................. 524-Methoxypyrazolo[1,5a ]pyridin-2-amine 3.26, 4-Methoxy-N,Ndimethylpyrazolo[1,5a ]pyridin-2-amine 3.27, N-(4Methoxypyrazolo[1,5a ]pyridin-2-yl)acet amide 3.28 ............... 533.3 Summa ry ........................................................................................................ 553.4 Experimental Section ..................................................................................... 553.4.1 General Methods ................................................................................. 553.4.2 Preparation of 2 -(2,4-Dinitrophenoxy)-1H -isoindoline-1,3(2 H )-dione 3.41 ..................................................................................................... 563.4.3 Preparation of O -(2,4-Dinitrophenyl)hydroxylamine 3.35 ..................... 563.4.4 Preparation of 4-(Ben zyloxy)pyridi ne 3.34 ........................................... 573.4.5 General Procedure for the Preparation of Compounds 3.32 and 3.31 ..................................................................................................... 573.4.6 General Procedure for the Pr eparation of Compounds 3.43, 3.42, 3.44, and 3.45 ...................................................................................... 583.4.7 Preparation of Pyrazolo[1,5a ]pyridin-4-ol 3.46 ................................... 593.4.8 Preparation of 4 -Methoxypyrazolo[1,5a ]pyridine 3.47 ........................ 603.4.9 Preparation of 4-Met hoxy-3-nitrosopyrazolo[1,5a ]pyridine 3.48 ......... 603.4.10 Preparation of (3-Methoxypyr idin-2-yl)metha nol 3.50 .......................... 603.4.11 Preparation of 2-(Chloromethyl)-3-methox ypyridine 3.51 .................... 613.4.12 Preparation of 2-(3-Methoxypyr idin-2-yl)acetoni trile 3.52 .................... 623.4.13 Preparation of (Z)-N'-Hydroxy-2-(3-methoxypyridin-2yl)acetimidami de 3.53 .......................................................................... 623.4.14 Preparation of N-(4 -Methoxypyrazolo[1,5-a] pyridin-2-yl)acetamide 3.28 and N-Acetyl-N-(4-methox ypyrazolo[1,5-a]pyridin-2yl)acetamide 3.54 ................................................................................ 634 SUMMARY OF A CHIEVEMENTS .......................................................................... 64LIST OF RE FERENCES ............................................................................................... 66BIOGRAPHICAL SKETCH ............................................................................................ 73

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7 LIST OF FIGURES Figure page 1 1 Numbering of the atoms from the pyrrolo[1,2 b ]pyridazine scaffold .................... 16 1 2 Mechanism for the formation of pyrrolopyridazine ................................ .............. 18 1 3 Mechanism for the formation of pyridinopyridazine ................................ ............ 18 1 4 Nu mbering of the atoms from the pyrazolo[1,5 a ]pyridine scaffold ..................... 20 1 5 Effect of 3 substituent on the product ratio ................................ ......................... 21 2 1 Exampl e of compounds showing antioxidant activity ................................ .......... 22 2 2 Examples of compounds showing antimicrobial activity ................................ ..... 23 2 3 Target Molecule ................................ ................................ ................................ .. 26 2 4 Synthesis plan ................................ ................................ ................................ .... 27 2 5 Modified Synthesis Plan ................................ ................................ ..................... 27 2 6 Mecha nism of the 1,3 dipolar cycloaddition ................................ ........................ 30 3 1 Example of mGluR5 modulators ................................ ................................ ......... 39 3 2 Examples for dopamine receptor antagonists ................................ .................... 40 3 3 Example of GSK3 kinase inhibitor ................................ ................................ ...... 41 3 4 Examples of protein kinase inhibitors ................................ ................................ 42 3 5 Examples of p38 MAP kinase inhibitors in clinical trials ................................ ..... 43 3 6 Examples of p38 kinase inhibitors ................................ ................................ ...... 43 3 7 Examples of treatment of herpes simplex ................................ ........................... 45 3 8 Molecules developed by GlaxoSmithKline ................................ .......................... 46 3 9 Examples of 3 amino pyrazolo[1,5 a ]pyridines as oxidation bases .................... 47 3 10 Target Molecules ................................ ................................ ................................ 48 3 11 Preparation of pyrazolo[1,5 a ]pyridine by flash vacuum pyrolysis ...................... 48 3 12 Synthesis plan ................................ ................................ ................................ .... 49

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8 LIST OF SCHEMES Scheme page 1-1 First examples of pyrrolo[1,2-b]pyrazines ........................................................... 16 1-2 Synthesis of indolizines ...................................................................................... 17 1-3 Formation of pyrrolo[1,2b ]pyridazine from pyridazinone-propionic acid ............ 19 1-4 Formation of mesoionic oxazolo[2,3-b]pyridazines ............................................. 19 1-5 Preparation of pyrazolo[1,5a ]pyridines .............................................................. 20 2-1 Synthesis of 2(3 -chloro-6-oxopyridazin-1(6 H )-yl)propanoic acid 2.14 ............... 28 2-2 The synthesis of 2(3 -(dimethylamino)-6-oxopyridazin-1(6H )-yl)propanoic acid 2.10 ............................................................................................................. 28 2-3 Results of the 1,3-dipolar cycloadditions ............................................................ 29 2-4 Attempts for the replacement of chlorine atom to dimethylamino group ............. 30 2-5 Hydrolysis under acidic condition ....................................................................... 31 2-6 Hydrolysis and decarboxylation of 2.6 ................................................................ 31 3-1 Synthesis of 4-benzyloxy pyridine 3.34 .............................................................. 50 3-2 The synthesis of O(2,4-dinitrophenyl)hydroxylamine 3.35 ................................. 50 3-3 Synthesis of N -amino-pyridinium 2,4-dinitrophanolates 3.31 and 3.32 ............... 51 3-4 Results of the 1,3-dipolar cycloadditions starting from N -amino(4 benzyloxy)pyridinium 2,4-dinitrophanolate 3.32 .................................................. 51 3-5 Results of the 1,3-dipolar cycloadditions starting from N-amino(3 methoxy)pyridinium 2,4-dinitrophanolate 3.31 .................................................... 52 3-6 Attempts for the synthesis of 2-methyl-4-nitropyrazolo[1,5-a]pyridine-5-ol 3.25 .................................................................................................................... 52 3-7 Plan to obtain 3.26, 3.27, and 3.28 ..................................................................... 53 3-8 Synthesis of 4-methoxy-3-nitrosopyrazolo[1,5a ]pyridine 3.48 ........................... 53 3-9 Plan to obtain targets 3.26, 3.27, and 3.28 ........................................................ 54

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9 3 10 Preparation of key intermediate 3.53 ................................ ................................ .. 54 3 11 Preparation of final target 3.28 ................................ ................................ ........... 55

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10 LIST OF ABBREVIATION S AcOH Acetic acid Ac 2 O Acetic anhyd ride ADHD Attention deficit hyperactivity disorder ADS Attention deficit syndrome Anal. Analytical ATP Mg 2+ Adenosine triphosphate magnesium salt aq. Aqueous C Celsius degree Calcd. Calculated Cu Cupper CDCl 3 Deut e rated chloroform CNS Central nervous syst em CoA Coenzyme A CSBP Cytokine suppressive anti inflammatory drug binding protein Chemical shift d Doublet dd Doublet of doublet DCM Methylene chloride DGAT Diacetylglycerolacyltransferase DMAD Dim e thyl acetylenedicarboxylate DMF Dimethylformamide DMSO d 6 Deut e rated dimethyl sulfoxide DNA Deoxyribonucleic acid EBV Epstein Barr virus

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11 e.g. Exempli gratia EGFR Epidermal growth factor receptor ErbB Epidermal growth factor receptor Et Ethyl et al And others Et 3 N Triethylamine EtOH Ethanol Fe Iron FGF Fibropl ast growth factor g Gram GPCR G protein coupled receptor GSK3 Glycogen synthase kinase h Hour HBr Hydrobromic acid HCl Hydrochloric acid HCMV Human cytomegalovirus HER Human epidermal growth factor receptor HHV Human herpes virus HMG CoA 3 Hydroxy 3 methyl glutaryl coenzyme A HNO 3 Nitric acid H 2 SO 4 Sulfuric acid HSV Herpes simplex virus Hz Hertz IC 50 Half maximal inhibitory concentration J Coupling constant

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12 K 2 CO 3 Potassium carbonate KOAc Potassium a c etate KOH Potassium hydroxide L Levorotary LED Light emitti ng diode M M ikromolar m M ultiplet MAP Mitogen activated protein MAPK Mitogen activated protein kinase MAPKAP K2 Mitogen activated protein kinase activated protein kinase 2 Me Methyl MeI Methyl iodide Me 2 NH Dimethylamine MeOH Methanol mGluR metabotropic gl utamate receptor mL Mi l liliter mmol M il l imole MOA Mechanism of action mp Melting point mRNA Messenger ribonucleic aid N Normal N 2 H 4 Hydrazine NH 2 OH Hydroxylamine NaNO 2 Sodium nitrite NaOEt Sodium ethoxide

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13 NaOH Sodium hydroxide NMR Nuclear magnetic resonanc e OLED Organic light emitting diode p Para PDGF Platelet derived growth factor Ph Phenyl PNS Peripherial nervous system PTK Protein tyrosine kinase q Quartet rt Room temperature s Singlet sLPA 2 Secretory phospholipase A 2 SOCl 2 Thionyl chloride t Triplet TD A 1 Tris(3,6 dioxaheptyl)amine TIE 2 Receptor tyrosine kinase 2 TMS Tetramethylsilane VEGF Vascular endothelial growth factor VZV Varicella zoster virus

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14 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science SYNTHESIS OF FUNCTIONALIZED PYRROLO[1,2 B ]PYRIDAZINES AND PYRAZOLO[1,5 A ]PYRIDINES By Judit Kovacs December 2010 Chair: Alan R. Katritzky Major: Chemistry The focus of this wor k was to synthesize novel derivatives of both pyrrolo[1,2 b]pyridazine and pyrazolo[1,5 a]pyridine for further application as component s of hair dyes. However, both classes of compounds also have a w ide range of biological activity. Chapter 1 presents a sh ort review of the most relevant syntheses of these compounds. Most commonly, they are synthesized by cycloaddition reactions. Chapter 2 presents a short review of the applications of the pyrrolo[1,2 b]pyrazines as biologically active compounds and as high ly fluorescent materials used in LEDs. They can be use d as both couplers and developers in oxidative hair dyeing compositions. It also has been shown that they could be synthesized efficiently through a 1,3 dipolar cycloaddition reaction between the corres ponding pyridazine derivatives and the appropriate alkyne. Chapter 3 presents a short review of the application of the pyrazolo[1,5 a]pyridines as biologically active compounds. Some derivatives even reached the clinical trial phase and they are still unde r development. Amino substituted pyrazolo[1,5 a]pyridine derivatives have been found to be suitable for use as oxidation bases. It also has been

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15 shown that they can be synthesized by the similar 1,3 dipolar cycloaddition reaction as pyrrolo[1,2 b]pyridazin se. Syntheses involve the almost exclusive use of N aminopyridinium salts and often require the generation of ylides. The N aminopyridinium precursors possessing no 2 substituent, which form the pyrazole ring upon cycl i zation with dipolarophiles. Finally, a summary of this work is presented in Chapter 4.

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16 CHAPTER 1 GENERAL INTRODUCTION 1 1 Overview of the Synthesis of P yrrolo[1,2 b ]pyridazines Pyrrolo[1,2 b ]pyridazine 1.1 is a N bridgehead aromatic heterocycle containing two nitrogen atoms, formally obtain ed by the condensation of pyridazine and pyrrole. The numbering of the atoms from the pyrrolo[1,2 b ]pyridazine scaffold, also known in the literature as 5 azaindolizine, is presented i n Figure 1 1 and used throughout this work. Figure 1 1. Numbering of the atoms from the pyrrolo[1,2 b ]pyridazine scaffold There is a high level of interest in the synthetic pathways leading to such derivatives and their properties. The synthetic methods are classified considering the starting compounds: syntheses starting from pyridazine and its derivatives, synthes es starting from a pyrrole ring; and syntheses starting from acyclic compounds. Herein only selected approaches for obtaining the pyrrolo[1,2 b ]pyridazine system are presented. 1.1.1 Synthesi s S tarting from Pyridazine and Acetylenic E sters The first pyrrolo[1,2 b]pyridazine derivatives were synthesized by this method in 1956 by Letsinger and Lasco. [56JOC764] (Scheme 1 1 ) Scheme 1 1 First examples of pyrrolo[1,2 b]pyrazines

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17 This reaction was first described by Diel s and Meyer in 1934 as a method to synthesize indolizines 1.5 starting from pyridine derivatives and DMAD (dimethyl acetylenedicarboxylate). [34JLAC129] (Scheme 1 2 ) Scheme 1 2 Synthesis of indolizines Acheson and Foxton found that the structure of the products is dependent on the solvent. Thus, in the case of a protic solvent, such as methanol, pyrrolopyridazines are obtained, while using acetonitrile as reaction medium affords the pyridinopyridazine derivative 1.8 [66JCS2218] This can be explained by the difference in the reaction mechanisms. The first step is the nucleophilic addition of the ring nitrogen atom to the triple bond with the formation of a zwitterionic intermediate 1.7, which can add a proton from methanol; the methoxide ion then generat es a new dipolar species 1.9, which reacts with a second molecule of DMAD to form 1.10 The next step is an intermolecular attack on the carbon of the ring, leading to the closing of the pyrrolidinic ring 1.1 1 which is subsequently aromatized by elimi nation of 1,2 dimethoxyethenol to give 1.12 [08ARKIVOC232] ( Figure 1 2 ) However, if a proton is not available, i.e. the reaction is in an aprotic solvent, the 1,3 dipole reacts with another molecule of DMAD to form 1.1 3 The next step is an intramolecular attack on the carbon of the ring, leading to the pyridinopyridazine 1.1 4 (Figure 1 3)

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18 Figure 1 2 Mechanism for the formation of pyrrolopyridazine Figure 1 3 Mechanism for the formation of pyridinopyridazine 1.1.2 The 1,3 dipolar Cycloaddition of Mesoionic O xaz olo[2,3 b ]pyridazines One of the general synthetic methods for obtaining pyrroloazines having a ni trogen atom at the junction of the two heterocyclic moieties is the 1,3 dipolar cycloaddition between mesoionic 1,3 oxazole 5 ones, also called munchnones, an d acetylenic dipolarophiles. [64ACIE135, 08S 813] Dumitrascu et al. were able to obtain pyrrolo[1,2 b ]pyridazine derivatives in good yield starting from pyridazinone propanoic acid 1.1 5 and DMAD in acetic anhydride at 90 C. [08S813] (Scheme 1 3 )

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19 Scheme 1 3 Formation of pyrrolo[1,2 b ]pyridazine from pyridazinone propionic acid When starting from pyridazinone acetic acid 1.18, along with unsubstituted pyrrolopyridazines 1.19, mesoionic oxazolo[2,3 b ]pyridazines 1.20 are also obtained. The formation of co mpound 1.20 was explained by Michael addition of DMAD to the C 3 atom from the oxazolic ring, a reaction which is known for other N heterocycles, such as pyrrole or indole. [71CC226, 07ARKIVOC180, 83T767] (Scheme 1 4 ) Scheme 1 4 Formation of mesoionic oxazolo[2,3 b]pyridazines 1.2 Overview of the Synthesis of P yrazolo[1,5 a ]pyridines Pyrazolo[1,5 a ]pyridazine 1.2 1 is a N bridgehead aromatic heterocycle containing two nitrogen atoms, formally obtained by the condensation of pyridine and pyrazole. The num bering of the atoms of the pyrazolo[1,5 a ]pyridine scaffold, also known as 3 azaindoline, is presented on Figure 1 4 and used throughout this work.

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20 Figure 1 4 Numbering of the atoms from the pyrazolo[1,5 a ]pyridine scaffold The preparation of pyrazo lo[1,5 a ]pyridines is influenced by the presence of the bridgehead nitrogen. Syntheses involve the almost exclusive use of N aminopyridinium salts and often require the generation of ylides. [68JOC3766, 73CPB2146, 75JHC481] The N aminopyridinium precursors can be divided into two major groups: those containing a 2 methylene group, which cyclize on treatment with acylating agents, or those possessing no 2 substituent, which form the pyrazole ring with dipolarophiles. 2,3 Substituted pyrazolo[1,5 a ]pyridines have been obtained, using a variety of dipolarophiles. Cyclization of ylides 1.2 2 with DMAD afforded the diester 1.24. [62TL387, 81JHC1149, 71JOC2978] Analogous products were obtained, using dibenzoylacetylene. [80JOC90] Huisgen et al. proposed the format ion of the dihydro intermediate 1.23, [62TL387] and a number of cycloadducts were later prepared by Sasaki et al. who demonstrated their facile dehydrogenation. [72JOC3106] (Scheme 1 5 ) The effect of 3 substituents in the pyridine ring on the ratio of 4 to 6 substituted products has been examined. The results indicate that (i) unless a large substituent is Scheme 1 5 Preparation of pyrazolo[1,5 a ]pyridines

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21 present at the 3 position, the cycloaddition occurs preferentially at C 2 of the pyridine ring, r egardless of the electron donating or electron withdrawing character of the substituent; (ii) steric hindrance to attack at C 2 by a 3 substituent becomes important with larger 3 substituents and (iii) the 3 hydroxy 3 amino and 3 acetamido pyridine N i mides produce exclusively 4 substituted pyrazolo[1,5 a ]pyridines. ( Figure 1 5 ) Figure 1 5 Effect of 3 substituent on the product ratio These data can be rationaliz ed in terms of electronic and steric factors together with hydrogen bond formation. As al ready suggested by Huisgen, [63ACIE633, 68JOC2291] the formation of compounds 1.27 and 1.28 must proceed in two stages: a concerted 1,3 dipolar cycloaddition between 1.25 and ethyl propiolate leading to the dihydropyridine intermediate 1.26 followed by de hydrogenation to give the final products Since most 1,3 dipolar cycloadditions are known to be stereospecific and hence irreversible, it is assume d that the first step is rate determining and responsible for determining the orientation. The 4 substituted product 1.27 forms if the interaction between the substituent and the ester group is not completely disfavored; otherwise the 6 substituted product predominates. [ 75 JCSPT406]

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22 CHAPTER 2 SYNTHESIS OF FUNCTIONALIZED P YRROLO[1,2 B]PYRIDAZINE 2. 1 Literature Ove rview Pyrrolo[1,2 b ]pyridazine derivatives show various biological activities and have interesting optical properties which make them useful in optoelectronic devices and as dyes. 2. 1 1 Biological Properties of Pyrrolo[1,2 b ]pyridazines Compounds with a ntioxidant/radical scavenging properties may have great therapeutic potential because free radicals are linked to several major diseases. It is reported that several 1 indolizinols are easily oxidized to stable free radicals and are therefore highly potent antioxidants. [89JOC3652] Nasir et. al. showed that the azaindolizine derivative 2. 2 is more active as a lipid peroxidation inhibitor than the corresponding indolizine 2. 1 .(Figure 2 1) [98BMCL1829] Figure 2 1. Example s of compounds showing antioxidant a ctivity A large number of pyridazine derivatives have been described in the literature with antimicrobial activity against Gram positive bacteria. [06H1871, 99APF415, 97APF69] The effect of the extension of the pyridazine with a fused benzene or pyrrolo r ing was studied and it was found that while the benzene ring decreases the activity the pyrrolo ring has no significant effect. (Figure 2 2) [07JHC1149]

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23 Figure 2 2. Examples of compounds showing antimicrobial activity Pyrrolo[1,2 b ]pyridazine derivativ es inhibit different enzymes which makes them important in the treatment of a variety of different disorders. [WO9118903, WO2005013907, EP1085021A1, WO03082208] A key enzyme in the synthesis of triglycerides is acetyl CoA:diacylglycerol acyltransferase (D GAT). Pyrrolopyridazines are useful for treating or preventing conditions and disorders (obesity, insulin resistance syndrome, type II diabetes, coronary heart disease) associated with DGAT in animals and particularly, in humans. [WO2005013907] They also h ave inhibitory activity against 3 hydroxy 3 methylglutaryl coenzyme A (HMG CoA) reductase and are therefore capable of lowering blood serum cholesterol and blood lipid levels. [WO9118903] Secretory phospholipase A 2 (sLPA 2 ) is a n enzyme that h ydrolyzes mem brane phospholipid s and has been considered to be a rate determining enzyme that governs the arachidonate cascade where arachidonic acid is the starting material. Lysophospholipids that are produced as by products in the hydrolysis of phospholipids are kno wn as important mediators in cardiovascular diseases. In order to normalize excess functions of the arachidonate cascade and the lysophospholipids, it is important to develop new compounds which inhibit the the activity or production of sPLA 2 The particip ation of sPLA 2 is considered to be extremely wide and its action is potent.

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24 Pyrrolopyridazine derivatives are useful for general treatment of symptoms, which are induced and sustained by an excess formation of sPLA 2 such as septic shock, adult respiratory dis t ress syndrome, injury, bronchial asthma, allergic rhinitis, chronic and rheumatism. [EP1085021A1] The tight regulation of signal transduction normally exerted by the array of kinase enzymes (human epidermal growth factor receptor family (HER), mitog en activated protein kinase (MAPK), members of the raf family of kinases, Src family of cytoplazmic protein tyrosine kinases, fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), platelet derived growth factor (PDGF), and so on) is of ten lost in malignant cells. Compounds which modulate these kinases are thus highly desirable for the treatment of disorders associated with aberrant cellular proliferation, such as cancer. Moreover, compounds which modulate the cytokines associated with t he inflammatory response are required for the treatment of inflammatory disorders. Some pyrrolopyridazine derivatives ha ve been found a s promising candidates for the treatment of the above conditions. [WO3082208A2, US20040209886A1] 2. 1 2 Optical Properties of Pyrrolo[1,2 b ]pyridazines Since the discovery of a thin film organic electroluminescent device by the team at Kodak [US4539507], organic light emitting diodes (LED/OLED) have become the most promising new optoelectronic devices for practical industrial applications. Electroluminescent thin films of organic molecules have been extensively investigated because of their low operating voltage, tunable red green blue output colors, high brightness, mechanical flexibility, and ease of fabrication. [87APL913] Although, polymeric as well as small organic molecules are well established electroluminescent materials used in the production of the thin film devices, it was realized that smaller

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25 organic units with facile emission color control and the easy assembly of multilayer devices would be advantageous. [02CR2357, 98CCR161] Investigations on synthesizing new blue luminous materials for application in electroluminescent display have attracted great attention, but there are still very few single component deep blue and pure red emitting dyes. [02CR2357, 98CCR161] Recently, many research groups reported pyrrolopyridazine derivatives as a new class of blue organic luminophors. [99JMC2183, 05T10227, 05M4698, 06S804, 10T278] Wudl et. al. demonstrated the possibility of tuning colors and energy levels by modifying the structures of these luminophors. [99JMC2183] Recent functionalization studies showed that the best fluorescent properties were achieved with a p chlorophenyl substituent in the 2 position of the pyrrolopyri dazine moiety, together with a carboethoxy group in the 7 position. [10T278] Included in the wide spectrum of application of pyrrolopyridazine derivatives, is their ability to dye the keratin of human hair. The most extensively used method to color hair i s an oxidative process that utilizes one or more hair coloring agents in combination with one or more oxidizing agents. Commonly, a peroxy oxidizing agent is used in combination with one or more developers or couplers, generally small molecules capable of diffusing into hair. In this procedure, a peroxide material activates the developers so they can react with the couplers to form larger sized compounds in the hair shaft to give a variety of shades and colors. [WO2005097952, FR 2934592 ] A wide variety of de velopers and couplers have been employed in such oxidative hair coloring systems and compositions. [DE102008061676, EP1847250A1, WO2006039990A1] However, there still exists a need for additional keratin dyeing compounds that can act

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26 as both developers and couplers and that safely provide color benefits. [WO2005097952] functionalized pyrrolo[1,2 b]pyrazine derivatives which can be used as both developers and couplers in hair coloring com positions. We have successfully synthesized 3 new pyrrolopyridazine derivatives by 1,3 dipolar cycloaddition. 2.2 Results and Discussion The aim of this project was to synthesize N 2 ,N 2 ,7 trimethylpyrrolo[1,2 b ]pyridazine 2,6 diamine 2. 5 ( Figure 2 3) which could be used as one active component of hair dyes. We chose to synthesize this target molecule by 1,3 dipolar cycloaddition of corresponding pyridazine derivatives and the appropriate alkyne. [08SL813] Also, using this route, we were able to extend the s cope of the cycloaddition reaction. Figure 2 3. Target m olecule 2.2.1. Retro Synthetic Analysis: Synthesis Plan The starting material for the synthesis of pyrrolo[1,2 b ]pyridazine derivative was 2 (3 (dimethylamino) 6 oxopyridazin 1(6 H ) yl)propanoic aci d 2.1 0 Compound 2.1 0 was easily prepared by a documented procedure [52JACS3222, 56JACS407, 56JACS2642] consisting of an N alkylation of 6 (dimethylamino)pyridazin 3(2 H ) one 2.1 1 [68AHC211, 79AHC365] with ethyl 2 bromopropanoate followed by acidic hydrolys is. ( Figure 2 4 )

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27 Figure 2 4. Synthesis plan Another possibility was to exchange one of the chlorine atoms by the dimethylamino group after the cyclization reaction. ( Figure 2 5) We chose this route, because the yield reported for the hydrolysis of 3 chl oro N,N dimethylp y ridazin 3 amine was low. [JP58 140092] Figure 2 5. Modified Synthesis Plan

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28 2.2.2. The S ynthesis of 2 (3 C hloro 6 oxopyridazin 1(6 H ) yl)propanoic A cid 2.14 and 2 (3 ( D imethylamino) 6 oxopyridazin 1(6 H ) yl)propanoic A cid 2.10 The hydroly sis of 3,6 dichloropyridazine 2.12 was carried out under basic conditions to give 6 chloro 2 H pyridazin 3 one 2.15 in 7 8 % yield. [89BKCS614] Alkylation of 2. 1 5 with ethyl 2 bromopropanoate 2.16 in the presence of sodium ethoxide afforded 2.17 in 78% yield The hydrolysis of 2.17 in hydrochloric acid gave 2 (3 chloro 6 oxopyridazine 1(6 H ) yl)propanoic acid 2.14 in 95 % yield. (Scheme 2 1 ) Scheme 2 1 Synthesis of 2 (3 chloro 6 oxopyridazin 1(6 H ) yl)propanoic acid 2.14 6 Chloro N,N dimethylpyridazine 3 ami ne 2.18 was obtained by the reaction of 3,6 dichloropyridazine 2.12 with dimethylamine in 87% yield. [75JMC741] Hydrolysis of 2.18 under acidic conditions gave the desired product 2.11 in 55% yield. [JP58140092] Alkylation of 2.11 with ethyl 2 bromopropano ate 2.16 in the presence of sodium ethoxide afforded compound 2.19 in 47% yield. The hydrolysis of 2.19 with 5N hydrochloric acid was carried out under reflux to obtain 2 (3 (dimethylamino) 6 oxopyridazin 1(6 H ) yl)propanoic acid 2.10 in 82% yield. (Scheme 2 2 ) Scheme 2 2 The synthesis of 2 (3 (dimethylamino) 6 oxopyridazin 1(6 H ) yl)propanoic acid 2.10

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29 2.2.3. 1,3 Dipolar Cycloaddition Pyrrolopyridazine derivatives 2.6, 2.7, and 2.13 were obtained by the reaction of the above pyridazinone propanoic acids w ith dimethyl but 2 ynedioate 2.8 or methyl propiolate 2.9 in 37%, 25%, and 35% yield, respectively. (Scheme 2 3 ) Scheme 2 3 Results of the 1,3 dipolar cycloadditions The proposed mechanism of 1,3 dipolar cycloaddition between mesoionic 1,3 oxazole 5 one s and acetylenic dipolarophiles is described in the literature. [08S813] In the first step t he mechanism involves the generation of the previously unknown mesoionic structures 2.20 by cyclodehydration of acids 2.14 or 2.10 through reaction with acetic anhy dride. T he intermediate adducts 2.22 resulting from mesoionic 1,3 dipole 2.21 and dipolarophile (DMAD), lose carbon dioxide to giv e the fused pyrroles 2.6, 2.7, 2.13 ( Figure 2 6 )

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30 Figure 2 6 Mechanism of the 1,3 dipolar cycloaddition 2.2.4. Attempts to Obtain the Final Target According to our original work plan depicted in Figure 2 5 we tried to replace the chlorine in compound 2.13 by the dimethylamino group under various conditions. The first attempt was to reflux the pyrrolopyridazine derivative 2.1 3 in a 40% dimethylamine solution in ethanol, but even after 48 hours, only starting material was recovered. Harsher conditions were then employed such as heating the reaction mixture in a sealed tube at 100C for 12 hours, but the starting material decom posed (Scheme 2 4 ) Scheme 2 4 Attempts for the replacement of chlorine atom with a dimethylamino group Attempts to hydrol ize and decarboxylate 2.6 were not successful under a variety of conditions. Under acidic conditions at room temperature, t he corres ponding diacid 2.23 mixed with the monoester 2.24 in a ratio of 2:1 based on 1 H NMR was obtained. (Scheme 2 5 ) This result suggests that hydrolysis can proceed by two pathways. At elevated temperature, the starting material decomposed.

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31 Scheme 2-5. Hydrolysis under acidic condition The hydrolysis of 2.6 was achieved under basic conditions to 2.23 and decarboxylation with copper in the presence of quinoline gave 2.25 in 37% yield; but the compound decomposed within an hour Therefore, we tried ni trosation without isolating 2.25, using sodium nitrite in acetic acid, but again the starting ma terial decomposed. (Scheme 2-6) Scheme 2-6. Hydrolysi s and decarboxylation of 2.6 Finally, we tried nitrosation of compound 2.7, where the ester group is already missing from the 6 position but the reacti on was unsuccessful. This may be explained by the fact that the electrophilic substitution is strongly favored at position 5 and 7, but since in our case, both positions are occupied the reaction cannot proceed under conditions that would avoid decomposition of the starting material.[08ARKIVOC232] 2.3 Summary We were able to utilize 1,3-dipolar cycloaddition between py ridazinone-propanoic acids and an acetylenic dipolarophile in acetic anhydride as reaction medium at 90C, in

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32 order to synthesize pyrrolo[1,2 b ]pyridazines. However, we were not able to obtain our final target; the unsuccessful reactions provided an insight into the chemical properties of pyrrolopyridazine derivatives. 2.4 Experimental Section 2.4.1 General Methods Melting points were determined on a capillary point apparatus equipped with a digital thermometer. NMR spectra were recorded in CDCl 3 or DMSO d 6 with TMS as an internal standard for 1 H (300 MHz or 500 MHz) or solvent as an internal standard for 13 C (75 MHz or 125 MHz). Elemental analyses were performed on a CarloErba 1106 instrument. All starting materials were purchased from Sigma Aldrich and used without further purification. 2.4.2 Preparation of 6 C hloro 2 H pyridazin 3 one 2. 15 3,6 Dichloropyrid azine ( 0.9 g, 6 mmol) was dissolved in 4% aq. NaOH solution and heated under reflux for 4 h. After cool ing to room temperature the pH was adjusted to 7 8 by the addi tion of 10% aq. acetic acid. The precipitate was filtered and washed with water. The crude sample was recrystallized from methanol/water 1:1 mixture, to afford 6 chloro 2 H pyr idazine 3 one as yellow microcrystals in 78% yield; mp 140 141C; 1 H NMR (300 MHz, DMSO d 6 6.95 (d, J = 10.1 Hz, 1H), 7.49 (d, J = 10.1 Hz, 1H) ; 13 C NMR (75 MHz, DMSO d 6 132.6, 134.8, 137.5, 159.8 ; Anal. Calcd. for C 4 H 3 ClN 2 O : C, 36.81; H, 2.32; N, 21.46; found: C, 37.18; H, 2.20; N, 20.47. 2.4.3 Preparation of 6 C hloro N,N dimethylpyridazin 3 amine 2. 18 To a solution of 3,6 dichloropyridazine (1.5 g, 0.1 mol) in ethano l was added 25 mL dimethylamine as a 40% solution in water. The reaction mixture was heated under reflux for an hour, and the ethanol was then evaporated. The aqueous residue was

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33 extracted with chloroform, the combined organic layer was dried over magnesiu m sulfate and the filtrate was evaporated to give 6 c hloro N,N dimethylpyridazin 3 amine as white crystals in 88% yield; mp 102 104C (lit. mp 103 104C [75JMC741]); 1 H NMR (300 MHz, DMSO d 6 (d, J = 9.6 Hz, 1H), 7.4 6 (d, J = 9.6 Hz, 1H) ; 13 C NMR (75 MHz, DMSO d 6 1 15.4 1 28.4 1 45.2 159. 0. 2.4. 4 Preparation of 6 (D imethylamino)pyridazine 3(2 H ) one 2.11 6 Chloro N,N dimethylpyridazine 3 amine (1.0 g, 6.4 mmol) a nd potassium acetate (0.94 g, 9.6 mmol) were dissolved in acetic acid and heated under reflux for 4 hours. The acetic acid was evaporated under reduced pressure and the residue was dissolved in 10% aq. sodium hydroxide solution. The precipitate was filtere d and the filtrate was neutralized with 6N aq. hydrochloric acid. The precipitate was collected by filtration and recrystallized from acetone to give 6 ( d imethylamino)pyridazine 3(2 H ) one as yellow solid in 55% yield; mp 188 190C (lit. mp 189 191C [JP581 40092]) 1 H NMR (300 MHz, DMSO d 6 (d, J = 10.2 Hz, 1H), 7. 21 (d, J = 10.2 Hz, 1H) 11.84 (s, 1H); 13 C NMR (75 MHz, DMSO d 6 130.7 149.4 158.5. 2.4. 5 General P rocedure for the Preparation of C ompounds 2.17 and 2.19 Sod ium ( 0.1 g, 5.4 mmol) was dissolved in absolute ethanol. The stirred sodium ethoxide solution was cooled to 10 C and the appropriate pyridazin 3(2 H ) one (5.4 mmol) was added, followed by the dropwise addition, of ethyl 3 bromo 2 methylpropanoate ( 1.1 g, 6 .2 mmol) keeping the reaction temperature at 15 20C. After addition was complete the mixture was heated under reflux for 3 hours, cooled and filtered. Ethanol was removed from the filtrate under vacuum and the residue was dissolved in benzene. A small a dditional amount of sodium bromide was removed by filtration and the benzene was evaporated to give 2. 17 or 2. 19

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34 Ethyl 2 (3 C hloro 6 oxopyridazin 1(6H) yl)propanoate 2. 17 : Colorless oil (78%); 1 H NMR (300 MHz, CDCl 3 1.30 (t, J = 7.1 Hz, 3H), 1.73 (d, J = 7.3 Hz, 3H), 4.18 4.31 (m, 2H), 5.52 (q, J = 7.3 Hz, 1H), 6.98 (d, J = 9.6 Hz, 1H), 7.25 (d, J = 9.8 Hz, 1H) ; 13 C NMR (75 MHz, CDCl 3 14.0, 15.2, 57.3, 61.8, 131.7, 133.9, 137.6, 158.7, 169.6 ; Anal. Calcd. for C 9 H 11 ClN 2 O 3 : C, 46.87; H, 4.81; N, 12.15; found: C, 46.65; H, 4.76; N, 12.38. Ethyl 2 (3 ( D imethylamino) 6 oxopyridazin 1(6 H ) yl)propanoate 2.19: Colorless oil (47%); 1 H NMR (300 MHz, CDCl 3 1.02 (t, J = 7.1 Hz, 3H), 1.41 (d, J = 7.1 Hz, 3H), 2.71 (s, 6H), 3.92 4.03 (m, 2H), 5.34 (q, J = 7.1 H z, 1H), 6.64 (d, J = 10.0 Hz, 1H), 6.89 (d, J = 9.9 Hz, 1H), 7.06 (s, 1H) ; 13 C NMR (75 MHz, CDCl 3 14.1, 15.0, 38.7, 56.2, 61.2, 124.0, 130.7, 148.9, 157.6, 170.6 ; Anal. Calcd. for C 11 H 17 N 3 O 3 : C, 55.22; H, 7.16; N, 17.56; found: C, 55.59; H, 7.10; N, 17. 72. 2.4.6 General P rocedure for the P reparation of C ompounds 2.14 and 2.10 A mixture of the desired ester 2. 17 or 2. 19 (4.2mmol) and 5% hydrobromic acid wa s heated under reflux for 2 hours. The mixture was chilled and filtered to g i ve 2. 14 or 2. 10 2 (3 Chloro 6 oxopyridazin 1(6H) yl)propanoic A cid 2. 14 : White crystals (95%); mp 163 165C; 1 H NMR (300 MHz, DMSO d 6 1.51 (d, J = 7.1 Hz, 3H), 5.34 (q, J = 7.2 Hz, 1H), 7.13 (d, J = 9.8 Hz, 1H), 7.64 (d, J = 9.1 Hz, 1H) ; 13 C NMR (75 MHz, DMSO d 6 14.9, 57.0, 131.9, 134.4, 136.7, 158.2, 171.0 ; Anal. Calcd. for C 7 H 7 Cl N 2 O 3 : C, 41.50; H, 3.48; N, 13.83; found: C, 41.24 ; H, 3.44; N, 13.46. 2 (3 ( D imethylamino) 6 oxopyridazin 1(6H) yl)propanoic A cid 2.10: Yellow powder (82%); mp 198 200C; 1 H NMR (300 MHz, DMSO d 6 1.25 (d, J = 7.0 Hz, 3H), 2.65 (s, 6H), 5.06 (d, J = 7.1 Hz, 1H), 6.61 (d, J = 10.0 Hz, 1H), 7.23 (d, J = 10.0 Hz,

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35 1H) ; 13 C NMR (75 MHz, DMSO d 6 14.9, 38.2, 55.7, 125.1, 130.2, 148.6, 156.7, 171.6 ; Anal. Calcd. for C 9 H 13 N 3 O 3 : C, 51.18; H, 6.20; N, 19.89; found: C, 51.32; H, 6.31; N, 19.88. 2.4.7 General P rocedure for the P reparation of C ompounds 2.13, 2.6, and 2.7 The appropriate acid 2. 14 or 2. 19 (4.0 mmol) w as suspended with stirring in acetic anhydride and then the appropriate alkyne 2. 8 or 2. 9 (4.4 mmol) was added. The reaction m ixture was kept at 90C for 4 hours. The acetic anhydride was removed unde r reduced pressure and the residue was purified by column chromatography (hexanes ethylacetate) to give 2. 13 2. 6 or 2. 7 Dimethyl 2 C hloro 7 methylpyrrolo[1,2 b ]pyridazine 5,6 dicarboxylate 2.13: Yellow powder (35%); mp 150 152C; 1 H NMR (300 MHz, CDCl 3 2.67 (s, 3H), 3.95 (s, 3H), 4.00 (s, 3H), 6.91 (d, J = 9.5 Hz, 1H), 8.40 (d, J = 9.5 Hz, 1H) ; 13 C NMR (75 MHz, CDCl 3 9.8, 51.7, 52.4, 103.4, 115.9, 119.0, 126.8, 129.1, 129.8, 147.7, 163.4, 165.6 ; Anal. Calcd. for C 12 H 11 Cl N 2 O 4 : C, 50.99; H, 3.92; N, 9.91; found: C, 50.73; H, 3.59; N, 10.21. Dimethyl 2 ( D imethylamino) 7 methylpyrrolo[1,2 b ]pyridazine 5,6 dicarboxylate 2.6: Yellow microcrystals (37%); mp 148 150C; 1 H NMR (300 MHz, CDCl 3 2.33 (s, 3H), 2.88 (s, 6H), 3.65 (s, 3H), 3.71 (s, 3H), 6.40 (d, J = 10.0 Hz, 1H), 7.89 (d, J = 9.9 Hz, 1H) ; 13 C NMR (75 MHz, CDCl 3 9.8, 38.2, 51.2, 51.9, 106.7, 125.4, 127.8, 128.5, 154.5, 164.2, 166.5 ; Anal. Calcd. for C 14 H 17 N 3 O 4 : C, 57.72; H, 5.88; N, 14.42; found: C, 57.64; H, 5.99; N, 14.29. Methyl 2 ( D imet hylamino) 7 methylpyrrolo[1,2 b ]pyridazine 5 carboxylate 2.7: Green crystals (35%); mp 125 127C; 1 H NMR (300 MHz, CDCl 3 2.18 (s, 3H), 2.80 (s, 6H), 3.63 (s, 3H), 6.24 (d, J = 9.8 Hz, 1H), 6.60 (s, 1H), 7.89 (d, J = 9.8 Hz, 1H) ;

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36 13 C NMR (75 MHz, CDCl 3 ) 11.0, 38.3, 50.8, 104.7, 111.3, 125.5, 126.0, 127.3, 154.4, 165.3 ; Anal. Calcd. for C 12 H 15 N 3 O 2 : C, 61.79; H, 6.48; N, 18.01; found: C, 61.69; H, 6.34; N, 17.81.

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37 CHAPTER 3 SYNTHESIS OF FUNCTIONALIZED P YR AZ OLO[1, 5 A ]PYRIDINE 3 1 Literature Overview Pyraz olo[1,5 a ]pyridine derivatives show a range of biological activity and have important redox properties, which make them useful in optoelectronic devices and as dyes. 3 1 1 Biological Properties of Pyrazolo[1,5 a ]pyridines It has been found that certain p yrazolopyridine derivatives are potent mGluR5 modulators. Therefore, these substances may be therapeutically beneficial in the treatment of conditions which involve abnormal glutamate neurotransmission or in which modulation of mGluR5 receptors results in therapeutic benefit. These substances are preferably administered in the form of a pharmaceutical composition, wherein they are present together with one or more pharmaceutically acceptable diluents, carriers, or excipients. [WO2003078435] Neuronal stimuli are transmitted by the central nervous system (CNS) through the interaction of a neurotransmitter released by a neuron, and the neurotransmitter has a specific effect on a neuroreceptor of another neuron. L glutamic acid is considered to be a major excita tory neurotransmitter in the mammalian CNS, consequently playing a critical role in a large number of physiological processes. Glutamate dependent stimulus receptors are divided into two main groups. The first group comprises ligand controlled ion channels whereas the other comprises metabotropic glutamate receptors (mGluR). Metabotropic glutamate receptors are a subfamily of G protein coupled receptors (GPCR). There is increasing evidence for a peripheral role of both ionotropic and metabotropic glutamate receptors outside the CNS e.g, in chronic pain states. At present, eight different members of these mGluRs

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38 are known. The mGluR5 modulators have been shown to modulate the effects of the presynaptically released neurotransmitter glutamate via postsynaptic mechanisms. Moreover, as these modulators can be both positive and/or negative mGluR5 modulators, such modulators may increase or inhibit the effects mediated through these metabotropic glutamate receptors. Of particular interest are those modulators whi ch are negative mGluR5 modulators. Such modulators decrease the effects mediated through metabotropic glutamate receptors. Since a variety of patho physiological processes and disease states affecting the CNS are thought to be related to abnormal glutamate neurotransmission, and mGluR5 receptors are shown to be expressed in many areas of the CNS and in PNS (peripheral nervous system), modulators of these receptors could be therapeutically beneficial in the treatment of diseases involving CNS and PNS. Theref ore, mGluR5 positive or negative modulators may be administered to provide neuroprotection and/or disease modification in the following acute or chronic pathological conditions or to provide a symptomatological effect on the following conditions: Alzheimer 's disease, Creutzfeld Jakob's syndrome/disease, attention deficit hyperactivity disorder (ADHD), attention deficit syndrome (ADS), depression, migraine, Tourette's syndrome. Positive modulators may be particularly useful in the treatment of positive and n egative symptoms in schizophrenia and cognitive deficits in various forms of dementia and mild cognitive impairment. [EP2090576, EP483836, WO2003078435] (Figure 3 1) Dopamine receptors, which belong to the class A rhodopsin like G protein coupled receptors can be divided phylogenetically into D 1 like receptors comprising the subtypes D 1 and D 5 and a D 2 like group including D 2 D 3 and D 4 [91DNP150]

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39 Figure 3 1. Example of mGluR5 modulators Interestingly, the D 3 receptor mRNA has a high abundance in limbi c brain areas associated with cognitive and emotional functions [91N610] and, therefore, can be considered as particularly related to affective disorders. [93N442] Thus, the D 3 receptor has been regarded as an interesting therapeutic target for the treatme nt of induced dyskinesia, and cocaine addiction. [00DF587, 00MP531, 93HMG767, 96MC1941, 02BMCL633] (Figure 3 2) An important large group of enzymes is the protein kinase enzyme family. Currently, there are about 50 0 different known protein kinases. Protein kinases serve to catalyze the phosphorylation of an amino acid side chain in various proteins by the transfer of the phosphate of the ATP Mg 2+ complex to said amino acid side chain. These enzymes control the maj ority of the signaling processes inside cells, thereby governing cell function, growth, differentiation and destruction (apoptosis) through reversible phosphorylation of the hydroxyl groups of serine, threonine and tyrosine residues in proteins.

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40 Figure 3 2. Examples for dopamine receptor antagonists Studies have shown that protein kinases are key regulators of many cell functions, including signal transduction, transcriptional regulation, cell motility, and cell division. Several oncogenes have also been shown to encode protein kinases, suggesting that kinases play a role in oncogenesis. These processes are highly regulated, often by complex intermeshed pathways where each kinase will itself be regulated by one or more kinases. Consequently, aberrant or in appropriate protein kinase activity can contribute to the rise of disease states associated with such aberrant kinase activity. Due to their physiological relevance, variety and ubiquity, protein kinases have become one of the most important and widely stu died families of enzymes in biochemical and medical research. One type of protein kinase is protein tyrosine kinases (PTK). Aberrant PTK activity has been implicated in a variety of disorders including psoriasis, rheumatoid arthritis, bronchitis, and cance r. Development of effective treatments for such disorders is a constant and ongoing enterprise in the medical field. The ErbB family of PTKs, which includes c ErbB 2, EGFR, and ErbB 4, is one group of PTKs that has attracted interest as a therapeutic targe t. Currently, of special interest, is the role of ErbB family PTKs in hyperproliferative disorders, particularly human malignancies. Elevated EGFR activity

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41 has, for example, been implicated in non small cell lung, bladder, and head and neck cancers. Furthe rmore, increased c ErbB 2 activity has been implicated in breast, ovarian, gastric and pancreatic cancers. Consequently, inhibition of ErbB family PTKs should provide a treatment for disorders characterized by aberrant ErbB family PTK activity. [US5773476, WO9935 146 ] However, many compounds used as inhibitors of protein kinases so far have shown lack of specificity, undesired side effects that may be caused by disadvantageous inhibitory properties against more than one type of protein kinase, lack of effici ency due to high specificity, efficiency only against certain diseases, development of resistance during administration and/or comparable undesirable properties. Certain 4 substituted hydrazono pyrazolopyrimidines have been described for use as GSK3 kinase inhibitors in the treatment of e.g. diabetes and TIE 2 kinase related diseases. [WO04009602, WO04009596, WO04009597]. (Figure 3 3) Figure 3 3. Example of GSK3 kinase inhibitor It has been found surprisingly, that a number of protein kinases which can be involved in signal transmission mediated by trophic factors and in the manifestation of

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42 diseases that involve the activity of protein kinases, can be inhibited by a pyrazolo[1,5 a ]pyridine 3 carboxylic acid compound. [WO2007065664] (Figure 3 4) Figure 3 4. Examples of protein kinase inhibitors MAPKAP K2 (mitogen activated protein kinase activated protein kinase 2) is a serine/threonine kinase and operates downstream of p38 kinase in the stress induced MAPK pathway. This p38 kinase pathway is activated by various stress related extracellular stimuli such as heat, ultraviolet radiation, bacterial lipopolysaccharide or inflammatory cytokines. The activation of this pathway causes phosphorylation of transcription and initiation factors and affects cell divisi on, apoptosis, cell differentiation, inflammatory response and infiltration of cancer cells. P38, also known as cytokine suppressive anti inflammatory drug binding protein (CSBP), is a member of the mitogen activated protein (MAP) kinase family that is in volved in stress and inflammatory response signal transduction pathways. [94N739, 96JLB152] A large number of small molecular inhibitors of p38 have been reported, and many are undergoing clinical trials for the treatment of inflammatory and autoimmune dis disease, psoriasis and surgery induced tissue injury. [06CTMC113, 05CTMC1017, 06MRR1] Recently,the potential utility of inhibiting p38 for the treatment of ischemic heart disease was also proposed.6 The most

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43 clin ically advanced p38 MAP kinase i nhibitors include SCIO 469 (talmapimod) 3.10 and VX 702 3.11 which are currently in phase 2 clinical trials for the treatment of rheumatoid arthritis and additional indications. [07PT192, 08BMCL5428] (Figure 3 5) Figure 3 5. Examples of p38 MAP kinase inhibitors in clinical trials As part of a lead optimization program, 2 (4 fluorophenyl) 3 (4 pyridinyl)pyrazolo [1,5 a]pyridine was identified as a promising p38 kinase inhibitor with an IC 50 of 0.12 M. Cheung et. al. trie d to improve the pharmacokinetic properties of this series by identification of a key potential site of oxidative metabolism on the pyrazolo [1,5 a]pyridine core and attachment of various substitutions at that site to inhibit metabolism. They found compoun d 3.1 3 the most active in this series. (Figure 3 6) Figure 3 6. Examples of p38 kinase inhibitors Herpes viruses are among the most prevalent infectious agents known and have the ability to infect nearly every animal species. This family contains eight k nown human viruses, herpes simplex virus 1 (HSV 1), HSV 2, varicella zoster virus (VZV), human

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44 cytomegalovirus (HCMV), Epstein Barr virus (EBV), and human herpesviruses 6 8 (HHV 6, HHV 7, and HHV 8). [01FV2381] The severity of the viral infections can rang e from the host being asymptomatic due to adequate control of the virus by the immune system to discomfort caused by oral fever blisters to death in certain immunocompromised individuals or neonates. [06EOP2271] The current gold standard therapy, valacyclo vir, is well known, widely used, and exceptionally well tolerated. While this has been an extremely successful therapy for patients, there is still a goal to improve treatment in the areas of time to healing of lesions, attenuation of pain, and reduction i n the frequency of reactivations. A major goal of our current efforts has been to find novel therapeutic agents to control viral replication through alternative mechanisms of action (MOA) such that potential synergy and complimentarity with valacyclovir ty pe of treatments may exist. Previous antiviral research on HSVs has primarily focused on the development of nucleoside analog ue s that target the viral polymerase. [03ERAT283] Early nucleosides included idoxuridine, vidarabine, and trifluridine. These are still used topically, but are too toxic for use as first line treatment. [01H23] Development of acyclovir ( 3.14 Zovirax), [93MVS2] a potent, specific, and well tolerated nucleoside inhibitor of herpes DNA polymerase, was a milestone in the development of antiviral drugs in the late 1970s and spurred development of a number of other nucleoside analog ue s. Currently, only the nucleosides acyclovir, valacyclovir 3.15 famciclovir 3 1 6 and penciclovir 3.17 are recommended for the treatment of herpes simplex di sease [05BMC5346] ( Figure 3 7)

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45 Figure 3 7. Examples for the treatment of herpes simplex Though numerous strategies and considerable effort h ave been expended in the search for the next generation anti herpetic therapy, it has proved difficult to outperf orm acyclovir. Vaccines, interleukins, interferons, therapeutic proteins, and antibodies with specific or non specific mode of action have lacked either the specificity or the safety to replace the currently available nucleosides as first line treatment. [ 05BMC5346] Small molecule drugs have recently received considerable attention as potential next generation anti herpetics. Immunomodulators (imiquimod and resiquimod), [01JID196] non nucleoside viral polymerase inhibitors (4 hydroxyquinoline 3 carboxamides ), [02RMV167] and viral helicase inhibitors (thiazolylphenyl and thiazolylamide) [02NM392] appear to be among the most promising investigational drugs. The pyrazolo[1,5 a ]pyridines of this class were shown not to be DNA synthesis inhibitors and thus have a mechanism of action different from currently marketed polymerase inhibitors. This prompted the directed chemistry effort around this core to

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46 identify a potent and safe agent with drug like properties. [06BMC944, 07BMCL2858] ( Figure 3 8) Figure 3 8. Mole cules developed by GlaxoSmithKline 3 1 2 Pyrazolo[1,5 a ]pyridines as Dyeing A gents It is known that keratin fibers especially human hair may be dyed with compositions containing oxidation dye precursors, in particular ortho or para phenylenediamines, ortho or para aminophenols, and heterocyclic compounds such as derivatives of diaminopyrazole called generally oxidation bases. The oxidation dye precursors, or oxidation bases are colorless or weakly colored compounds which, when combined with oxidizing produc ts, can give birth through a process of oxidative condensation to colored compounds and dyes. These compounds have in common an amino group and a hydroxyl group or two amino groups, which allow them to use oxidized. It is also known that the shades obtaine d with these oxidation bases can be varied by combining them with couplers or coloration modifiers, the latter being chosen especially from aromatic meta aminophenols, meta diphenols and certain heterocyclic

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47 compounds. The variety of molecules involved in the oxidation bases and couplers affords a rich palette of colors. Staining "permanent" obtained from these oxidation dyes must moreover satisfy a number of requirements. Thus, there should be no disadvantage toxicologically, they must allow shades to be o btained in the desired intensity and have good resistance to external agents (light, bad weather, washing, permanent waving, perspiration, and rubbing). The dyes should also cover gray hair, and obtain color differences as low as possible throughout the sa me keratin fiber. Pyridines are used for oxidation dyeing of keratin fibers and are also known as couplers for dyeing keratinous fibers Examples include 2,5 diaminopyridine, 2 (4 methoxyphenyl)amino 3 amino pyridine, 2,3 diamino 6 methoxy pyridine, 2 ( methoxyethyl)amino 3 amino 6 methoxy and 3,4 diaminopyridine as oxidation base. [GB1026978, GB1153196, DE3132885, DE3233540, DE1149496]. A new family of 3 amino pyrazolo[1,5 a ]pyridines has been found, quite surprisingly to be suitable for use as oxidati on bases, and for obtaining dye compositions which lead to strong staining even at neutral pH, with good resistance to external agents (light, bad weather, washing, permanent waving, perspiration, and rubbing). [WO2001035917, WO2002076416, WO2002076417, WO 2002076418, WO2002076419] ( Figure 3 9) Figure 3 9. Examples of 3 amino pyrazolo[1,5 a ]pyridines as oxidation bases

PAGE 48

48 functionalized pyrazolo[1,5 a ]pyridine derivatives to be used as o xidation bases in hair coloring compositions, and 5 new pyrazolopyridine derivatives were synthesized by 1,3 dipolar cycloaddition. 3.2 Results and Discussion The aim of this project was to synthesize 2 methyl 4 nitropyrazolo[1,5 a ]pyridin 5 ol 3. 25, 4 met hoxypyrazolo[1,5 a ]pyridin 2 amine 3.26, 4 methoxy N,N dimethylpyrazolo[1,5 a ]pyridin 2 amine 3.27, N (4 methoxypyrazolo[1,5 a ]pyridin 2 yl)acetamide 3.28 ( Figure 3 10) which could be used as active component of hair dyes. We chose to synthesize these targ et molecules by 1,3 dipolar cycloaddition of the corresponding N amino pyridinium salts with the appropriate alkyne. [05JMC5771] Also, using this route, we were able to extend the scope of the cycloaddition reaction. Figure 3 10. Target Molecules 2.2.1. Retro Synthetic Analysis: Synthesis Plan Target molecule 3.25 and its synthesis is described in the literature [94AJC991, 94AJC1009] by flash pyrolysis of the appropriately substituted 1 (1 H pyrazol 1 yl)prop 2 yn 1 one ( Figure 3 11) Figure 3 11. Pre paration of pyrazolo[1,5 a ]pyridine by flash vacuum pyrolysis

PAGE 49

49 Another widely used method for the preparation of pyrazolo[1,5 a ]pyridines is the 1,3 dipolar cycloaddition between N amino pyridinium salts and acetylenic dipolarophiles. [ 73CR255 80JCSCC1109, 81JHC1149 ] The starting material s for the synthesis of pyr az olo[1, 5 a ]pyridine derivative s w ere the substituted N amino pyridinium 2,4 dinitro phenolate 3.31, 3.32, which can be prepared by electrophilic amination of the substituted pyridines 3.33, 3.34. [77S1] ( Figure 3 12) Figure 3 12. Synthesis plan 3.2.2. The Synthesis of the Starting M aterials: N amino pyridinium 2,4 dinitroph e nolates 3.31 and 3.32 Substituted pyridines 3.33 and 3.34 3 Methoxy pyridine 3.33 the starting material for compounds 3.26 28, is commercially available but 4 benzyloxy pyridine 3.34 had to be prepared from 4 chloropyridine 3.3 6 as described by Ballesteros et. al. [87T2557] 4 Chloropyridine hydrochloride 3.36 was basified and then reacted with benzyl alcohol 3.37 in the

PAGE 50

50 prese nce of TDA 1 (tris(3,6 dioxaheptyl)amine) 3.38 to give 4 benzyloxy pyridine 3.34 in 75% yield. (Scheme 3 1) N amino pyridinium 2,4 dinitroph e nolates 3.31 and 3.32 In order to carry out the electrophilic amination of the pyridine nitrogen, the amination re agent, O (2,4 dinitrophenyl)hydroxylamine 3.35 was prepared in two steps by a known method. [03JOC7119]. N Hydroxypthalimide 3.39 was reacted with 2,4 Scheme 3 1 Synthesis of 4 benzyloxy pyridine 3.34 dinitrochlorobenzene 3.40 in the presence of trieth ylamine to obtain the amino protected O (2,4 dinitrophenyl)hydroxylamine 3.41 Deprotection was achieved by using hydrazine to yield the desired amination reagent 3.35 (Scheme 3 2 ) Scheme 3 2 The synthesis of O (2,4 dinitrophenyl)hydroxylamine 3.35 With the amination reagent in hand, the electrophilic amination was carried out with both pyridine starting materials. The reaction with 3 methoxy pyridine 3.33 has been described. [WO2008113559] Following the published procedure the pyridine derivatives were reacted with the amination reagent in dichloromethane for 20 h at room

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51 temperature to give the corresponding N amino pyridine 2,4 dinitrophenolate in almost quantitative yield. (Scheme 3 3 ) Scheme 3 3 Synthesis of N amino pyridinium 2,4 dinitroph e n olates 3.3 1 and 3.3 2 3.2.3. 1,3 Dipolar Cycloaddition Pyrazolopyridine derivatives 3.42, 3.43 were obtained by the reaction of N amino (4 benzyloxy)pyridinium 2,4 dinitrophanolate 3.3 2 with ethyl but 2 ynoate 3.30 or methyl propiolate 3.29 in 20% and 51% y ield, respectively. (Scheme 3 4 ) Scheme 3 4 Results of the 1,3 dipolar cycloadditions starting from N amino (4 benzyloxy)pyridinium 2,4 dinitrophanolate 3.3 2

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52 When N amino (3 methoxy)pyridinium 2,4 dinitroph e nolate 3.3 1 was reacted with methyl propiolate 3.29 under the same conditions, two isomers of the ring closed product were isolated, the desired isomer 3.44 in 36% and 3.45 in 15% yield. (Scheme 3 5 ) Scheme 3 5 Results of the 1,3 dipolar cycloadditions starting from N amino ( 3 meth oxy)pyridinium 2, 4 dinitroph e nolate 3.3 1 3.2.4. Attempts to Obtain the Final Target 2 M ethyl 4 nitropyrazolo[1,5 a ]pyridin 5 ol 3. 25 The plan to obtain the titled target was to carry out the decarboxylation and deprotection of the pyrazolopyridine derivative 3.42 and then obtain the final target by nitration according to a literature procedure. [94AJC991] (Scheme 3 6 ) Scheme 3 6 Attempts for the synthesis of 2 methyl 4 nitropyrazolo[1,5 a]pyridine 5 ol 3.25 The decarboxylation/deprotection step was carried out in 48% hy drobromic acid solution at various temperatures. When the reaction was stirred at room temperature, there was no observed reaction even after 48 h. When the reaction was heated under reflux for 1 hour, deprotection occured, but not decarboxylation. When th e reaction was carried out under reflux for 6 hours, the starting material decomposed.

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53 4 Methoxypyrazolo[1,5 a ]pyridin 2 amine 3.26, 4 M ethoxy N,N dimethylpyrazolo[1,5 a ]pyridin 2 amine 3.27, N (4 M ethoxypyrazolo[1,5 a ]pyridin 2 yl)acetamide 3.28 The plann ed synthesis beyond 3.44 is shown in Scheme 3 7 Decarboxylation of 3.44 followed by nitrosation and reduction to obtain the amine 3.26 which would be converted to the other targets by methylation with methyl iodide to afford 3.27, or by acylation with a cetic anhydride to obtain 3.28. (Scheme 3 7) Scheme 3 7 Plan to obtain 3.26, 3.27, and 3.28 According to the plan, methyl 4 methoxypyrazolo[1,5 a]pyridine 3 carboxylate 3.44 was heated under reflux in 48% hydrobromic acid solution for 6 hours; however, under these conditions the de alkylation of the methoxy group occured as well as decarboxylation. The hydroxyl derivative 3.46 was methylated with methyl iodide to obtain 4 methoxypyrazolo[1,5 a]pyridine 3.47 in 21% yield over the two steps. The nitrosati on was carried out using sodium nitrite in acetic acid; but the product was the 3 nitroso derivative 3.48 and not the desired 2 nitroso (Scheme 3 8 ) Scheme 3 8 Synthesis of 4 m ethoxy 3 nitrosopyrazolo[1,5 a ]pyridine 3.48

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54 Since nitrosation did not occu r in the desired position, another route was chosen for the synthesis of these targets based on a literature procedure, which involves a cycli z ation reaction of (Z) N' hydroxy 2 (3 methoxypyridin 2 yl)acetimidamide 3.53 with acetic anhydride to provide the desired acylated target 3.28 in a separable mixture with the doubly acylated product 3.54. The hydrolysis of any of these acylated derivatives would lead to the desired amine derivative 3.26, which upon methylation would give the dimethylamino derivative 3.27. (Scheme 3 9 ) Scheme 3 9 Plan to obtain targets 3.26, 3.27, and 3.28 (Z) N' H ydroxy 2 (3 methoxypyridin 2 yl)acetimidamide 3.53 was prepared starting from 2 (hydroxymethyl)pyridin 3 ol 3.49. It was first methylated with methyl iodide to give (3 me thoxypyridin 2 yl)methanol 3.50 in 64% yield. The primary hydroxyl group was converted to chloro using thionyl chloride in 70% yield. 2 ( C hloromethyl) 3 methoxypyridine 3.51 was reacted with potassium cyanide to obtain 2 (3 methoxypyridin 2 yl)acetonitrile 3.52 in 27% yield. The reaction of 3.52 with hydroxylamine in the presence of base gave the key intermediate 3.53. (Scheme 3 10 ) Scheme 3 10 Preparation of key intermediate 3.53

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55 The reaction of (Z) N' hydroxy 2 (3 methoxypyridin 2 yl)acetimidamide 3.5 3 with acetic anhydride gave the two acylated pyrazolopyridine derivatives 3.28 and 3.54 in 25% and 9% yield, respectively. (Scheme 3 11 ) Scheme 3 11 Preparation of final target 3.28 3.3 Summary We were able to utilize 1,3 dipolar cycloaddition between N amino pyridinium salts and an acetylenic dipolarophile in acetic anhydride as reaction medium at 90C, in order to synthesize pyrazolo[1,5 a ]pyridines. However, we were not able to obtain all of our final targets; the unsuccessful reactions provided an i nsight into the chemical properties of pyrazolopyridine derivatives. 3 .4 Experimental Section 3 .4.1 General Methods Melting points were determined on a capillary point apparatus equipped with a digital thermometer. NMR spectra were recorded in CDCl 3 or DMS O d 6 with TMS as an internal standard for 1 H (300 MHz or 500 MHz) or solvent as an internal standard for 13 C (75 MHz or 125 MHz). Elemental analyses were performed on a CarloErba 1106 instrument. All starting materials were purchased from Sigma Aldrich and used without further purification.

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56 3 .4.2 Preparation of 2 (2,4 D initrophenoxy) 1 H isoindoline 1,3 (2 H ) dione 3 41 Triethylamine ( 21.5 mL, 154 mmol) was added in one portion to a suspension of N hydroxyphthalimide ( 25 g, 153 mmol) in acetone (500 mL) and the mixture was stirred at room temperature until it became a homogeneous solution. 2,4 Dinitrochlorobenzene ( 31 g, 153 mmol) was then added in one portion, and the reaction was stirred at room temperature for 2 h. T he reaction mixture was then poured into 500 m L of ice water. The precipitate was filtered and washed with cold methanol and hexanes. After drying it afforded 2 (2,4 dinitrophenoxy) 1 H isoindoline 1,3 (2 H ) dione as off white crystals in 89% yield; mp 186 188C (lit. mp 186C [03JOC7119]); 1 H MNR (300 MHz, CDCl 3 7.48 (d, J = 9.3 Hz, 1H), 7.91 7.96 (m, 2H), 7.96 8.01 (m, 2H), 8.45 (dd, J = 6.9, 2.3 Hz, 1H), 8.99 (d, J = 2.3 Hz, 1H) ; 13 C NMR (75 MHz, CDCl 3 116.0, 122.9, 124.9, 128.9, 129.7, 136.0, 143.4, 156.7, 162.3 3 .4.3 Preparation of O (2,4 D initrophenyl)hydroxylamine 3 35 A solution of hydrazine hydrate (8.85 g, 177 mmol) in methanol (60 mL) was added in one portion to a solution of 2 (2,4 dinitrophenoxy) 1 H isoindoline 1,3 (2 H ) dione (20 g, 60.7 mmol) in dichloromethane (400 mL) at 0C The reaction mixture rapidly became bright yellow, and a precipitate formed. The suspension was allowed to stand at 0C for 8 h, cold aq. HCl (1M, 400 mL) was added, and the reaction mixture was shaken rapidly at 0C. The reaction mixture was filtered th rough a loose cotton plug on a Buchner funnel, and the precipitate was washed three times with 50 mL of acetonitrile. The filtrate was poured into a separatory funnel, and the organic phase was separated. The aqueous phase was extracted with dichloromethan e (2x 100 mL), and the combined organic phases dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to give O (2,4 dinitrophenyl)hydroxylamine as

PAGE 57

57 orange crystals in 85% yield; mp 111 113C (lit. mp 112C [03JOC7119]); 1 H M NR (300 MHz, CDCl 3 (d, J = 9.6 Hz, 1H), 8 .4 5 (d d J = 9.5, 2.7 Hz, 1H) 8.77 (d, J = 2.6 Hz, 1H); 13 C NMR (75 MHz, CDCl 3 1 28.7 159. 6. 3 .4. 4 Preparation of 4 (B enzyloxy)pyridine 3.34 4 C hloropyridine ( 0.56 g, 5 mmol) was added to a suspension of powdered potassium hydroxide ( 1.1 g, 20 mmol) and potassium carbonate (5 mmol) in dry toluene (50 ml), and benzylalcohol ( 0.69 g, 7.5 mmol). After adding tris(3,6 dioxaheptyl)amine ( 0.2 g, 0.5 mmol) the reaction was stirred at 120C for 18 h. T he solvent was evaporated and the residue was dissolved in ethyl acetate. It was washed with 6N HCl and the aqueous phase was washed with ethyl acetate twice more. The aqueous phase was basified with 10% N aOH and extracted with ethyl acet ate, dried and evaporated to g i ve 4 (benzyloxy)pyridine as white crystals in 86% yield; mp 54 56C (lit mp 55 56C [87T2557]); 1 H MNR (300 MHz, CDCl 3 5.09 (s, 2H), 6.87 (d, J = 6.2 Hz, 2H), 7.36 7.50 (m, 5H), 8.43 (d, J = 6.0 Hz, 2H) ; 13 C NMR (75 MHz, C DCl 3 70.0, 110.7, 127.6, 128.5, 128.9, 153.8, 151.3, 164.8 3 .4. 5 General Procedure for the Preparation of Compounds 3.32 and 3.31 A suspension of the appropriate pyridine derivative (1.12 mmol) and O (2,4 dinitrophenyl)hydroxylamine (1.24 mmol) in met hylene chloride was stirred for 20 h at room temperature. After addition of diethylether the precipitate was filtered off and dried under reduced pressu re to give 3.32 or 3.31 1 Amino 4 (Benzyloxy)pyridinium 2,4 D initrophenolate 3.32 : Yellow microcrystals (99%); mp 134 136 C ; 1 H MNR (300 MHz, DMSO d 6 ) 5.42 (s, 2H), 6.34 (d, J = 9.8 Hz, 1H), 7.42 7.51 (m, 5H), 7.61 (d, J = 6.0 Hz, 2H), 7.72 7.81 (m, 3H), 8.58 8.61 (m, 1H), 8.68 (d, J = 5.9 Hz, 2H) ; 13 C NMR (75 MHz, DMSO d 6 71.8,

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58 113.8, 124.9, 126.2, 127.5, 128.4, 128.7, 128.8, 134.5, 143.4, 1 66.9, 169.7 ; Anal. Calcd. for C 18 H 16 N 4 O 6 : C, 56.25; H, 4.20; N, 14.58; found: C, 56.02; H, 3.95; N, 14.58. 1 Amino 3 methoxypyridinium 2,4 D initrophenolate 3.31: Yellow microcrystals (99%); mp 139 141 C (lit mp 140C [WO2008113559]); 1 H MNR (300 MHz, DMSO d 6 3.95 (s, 3H), 6.32 (dd, J = 6.3, 3.4 Hz, 1H), 7.75 7.80 (m, 1H), 7.91 (d, J = 3.4 Hz, 2H), 8.38 8.42 (m, 1H), 8.50 (br s, 2H), 8.58 (d, J = 3.2 Hz, 2H) ; 13 C NMR (75 MHz, DMSO d 6 57.2, 124.8, 125.0, 126.0, 126.6, 127.4, 128.2, 130.5, 136.0, 157. 9, 170.4 3.4.6 General Procedure for the Preparation of Compounds 3.43, 3.42, 3.44, and 3.45 To a mixture of the desired pyridinium 2,4 dinitrophenolate (1.43 mmol) and potassium carbonate (2.01 mmol) in dry DMF was added dropwise the appropriate alkyne 3. 29 or 3. 30 (1.51 mmol) and the mixture was stirred at room temperature for 16h. The precipitate was filtered off and the filtrate was evaporated. Then saturated NaHCO 3 solution was added, extracted with methylene chloride and washed with 1N HCl and water The organic layer was dried over magnesium sulfate filtered, and the filtrate evaporated under reduced pressure The crude product was purified by flash chromat ography (hexanes ethyl acetate) to g i ve 3.43, 3.42, 3.44 or 3. 45 Methyl 5 ( B enzyloxy)pyrazo lo[1,5 a ]pyridine 3 carboxylate 3.43 : Brown crystals (51%); mp 120 122C (lit mp 122 123C [05JMC5771]); 1 H MNR (300 MHz, CDCl 3 3.90 (s, 3H), 5.17 (s, 2H), 6.69 (dd, J = 7.4, 2.6 Hz, 1H), 7.38 7.54 (m, 5H), 8.29 (s, 1H), 8.35 (d, J = 7.4 Hz, 1H) ; 13 C NMR (75 MHz, CDCl 3 51.3, 70.9, 97.6, 102.7, 108.6, 128.0, 128.8, 129.0, 130.3, 135.5, 142.9, 145.5, 158.8, 164.3

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59 Ethyl 5 (B e nzyloxy) 2 methylpyrazolo[1,5 a ]pyridine 3 carboxylate 3.42: Off white powder (20%); mp 127 129C; 1 H MNR (300 MHz, CDCl 3 1.41 (t, J = 7.1 Hz, 3H), 2.62 (s, 3H), 4.36 (q, J = 7.0 Hz, 2H), 5.15 (s, 2H), 6.58 6.66 (m, 1H), 7.33 7.51 (m, 6H), 8.23 (d, J = 7.4 Hz, 1H) ; 13 C NMR (75 MHz, CDCl 3 14.9, 38.2, 55.7, 125.1, 130.2, 148.6, 156.7, 171.6 14.7, 14.8, 59.7, 70.7, 97.9, 107.7, 127.9, 128.7, 129.0, 129.6, 135.7, 144.2, 156.3, 158.6, 164.6 ; Anal. Calcd. for C 18 H 18 N 2 O 3 : C, 69.66; H, 5.85; N, 9.03; found: C 69.43; H, 5.95; N, 8.78. Methyl 4 M ethoxypyrazolo[1,5 a ]pyridine 3 carboxylate 3.44: Yellow powder (36%); mp 187 189C (lit mp 186 187C [WO2008113559]); 1 H MNR (300 MHz, CDCl 3 ) 3.90 (s, 3H), 3.94 (s, 3H), 7.19 (d, J = 7.8 Hz, 1H), 8.07 (d, J = 9.1 Hz 1H), 8.13 (s, 1H), 8.34 (s, 1H) ; 13 C NMR (75 MHz, CDCl 3 9 51.1, 56.1, 103.4, 111.7, 118.7, 122.1, 136.8, 144.0, 150.2, 136.8 Methyl 6 M ethoxypyrazolo[1,5 a ]pyridine 3 carboxylate 3.45: Yellow microcrystals (15%); mp 153 155C (lit mp 154C [WO200811 3559]); 1 H MNR (300 MHz, CDCl 3 3.91 (s, 3H), 4.04 (s, 3H), 6.69 (d, J = 7.7 Hz, 1H), 6.88 (t, J = 7.3 Hz, 1H), 8.21 (d, J = 6.7 Hz, 1H), 8.38 (s, 1H) ; 13 C NMR (75 MHz, CDCl 3 51.4, 56.2, 104.2, 113.4, 122.5, 145.3, 151.9, 162.8 3 .4. 7 Preparation of P yrazolo[1,5 a ]pyridin 4 ol 3 46 M ethyl 4 methoxypyrazolo[1,5 a ]pyrydine 3 carboxylate ( 0.4 g, 1.9 mmol) was treated wtih 48% hydrobromic acid (9.5 mL) and heated under reflux for 16 h. After cooling to room temperature the mixture was neutralized with 5N N aOH and extracted with diethylether. The organic layer was dried over magnesium sulfate evaporated and purified by flash chro matography (hexane/EtOAc 1:1) to gi ve pyrazolo[1,5 a ]pyridin 4 ol as yellow crystals ( 47% ) ; mp 200 202C (lit mp 200C [WO2008113 559]); 1 H MNR (300

PAGE 60

60 MHz, DMSO d 6 6.45 (d, J = 7.6 Hz, 1H), 6.61 (s, 1H), 6.69 (t, J = 6.1 Hz, 1H), 7.87 (s, 1H), 8.19 (d, J = 6.9 Hz, 1H), 10.48 (s, 1H) ; 13 C NMR (75 MHz, DMSO d 6 94.8, 102.8, 112.3, 120.4, 134.9, 140.2, 148.2 3 .4. 8 Preparation of 4 M ethoxypyrazolo[1,5 a ]pyridine 3 47 Pyrazolo[1,5 a ]pyridin 4 ol ( 0.12 g, 0 .9 mmol) and potassium hydroxide (0.1 g, 1.5 mmol) were suspended in dimethyl formamide (10 mL), then iodomethane (0.7 g, 5 mmol) was added, and the reaction mixture was stirred at ro om temperature for 24 h. The solvent was removed under reduced pressure and the residue was dissolved in ethyl acetate and extracted with water. The organic phase was dried over magnesium sulfate and the filtrate evaporated to gi ve crude 4 methoxypyrazolo[ 1,5 a ]pyridine as a yellow oil, which was used without further purification. 3 .4. 9 Preparation of 4 M ethoxy 3 nitrosopyrazolo[1,5 a ]pyridine 3 48 A solution of sodium nitrite (4.6 mmol) in water (2 mL) was added slowly at 0 o C to a stirred solution 4 metho xypyrazolo[1,5 a ]pyridine (3.4 mmol) in glacial acetic acid (4 mL). After 1h a green precipitate was formed, which was filtered, washed with water and dried under vacuum to give 4 methoxy 3 nitrosopyrazolo[1,5 a ]pyridine as a green powder (32%), m.p. 21 6.0 218.0 C. HRMS (ESI) calc. for [C 8 H 7 N 3 O 2 +H] + 178.0611; Found: 178.0615; 1 H MNR (500 MHz, DMSO d 6 ( s 3 H), 7.35 ( dd J = 8.1, 6.7 Hz, 1H), 7.57 ( d J = 8 .1 Hz, 1H), 7. 78 (s, 1H), 8. 66 (d, J = 6. 5 Hz, 1H) ; 13 C NMR (125 MHz, DMSO d 6 112.5 117.6 123.9 126.0 134.7 153.1, 158.2. 3 .4. 10 Preparation of (3 M ethoxypyridin 2 yl)methanol 3.50 Potassium hydroxide (0.52 g, 9.3 mmol) was ground to a powder under nitrogen, added DMSO (5 mL) and stirred for 20 min under nitrogen at room temperat ure. The mixture was cooled to 0C, and 2 (hydroxymethyl )pyridine 3 ol hydrochloride (0.5 g, 3.1

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61 mmol) was added. The slurry was stirred at 0C for 1 h before the addition of methyl iodide (0.2 mL, 3.1 mmol). The mixture was allowed to warm to room tempera ture and stirred under nitrogen overnight. Water (10 mL) was added, and the resultant solution was acidified to pH 1 with hydrochloric acid (5 N). The solution was washed with dichloromethane (3x20 mL), basified to pH 14 with sodium hydroxide (4 N), and ex tracted with dichloromethane (3x20 mL). The organic extracts were combined, washed with water, and saturated sodium chloride solution, dried over magnesium sulfate, filtered, and the filtrate evaporated to give (3 methoxypyridin 2 yl)methanol as a light br own needles (64%), mp 83 85C ; 1 H MNR (300 MHz, CDCl 3 ( s 3 H), 4.74 (s, 2 H), 7.12 7.24 ( m 2 H), 8.15 (d, J = 4.5 Hz, 1H ) ; 13 C NMR (75 MHz, CDCl 3 55.1 60.0 116.4 122.6 139.3 148.3 152.3 Anal. Calcd. for C 7 H 9 NO 2 : C, 60.42 ; H, 6.52 ; N, 10.07 ; found: C, 59.98 ; H, 6.61 ; N, 9.71 3 .4. 1 1 Preparation of 2 (C hloromethyl) 3 methoxypyridine 3.51 (3 methoxypyridin 2 yl)methanol (0.4 g, 2.9 mmol) was dissolved in dry chloroform (10 mL) and cooled to 5C. Thionyl chloride (0.3 mL, 4.3 mmol) was added t o this solution at such a rate that the temperature of the reaction mixture did not rise above 10C. After the addition was over, the temperature of the reaction mixture was allowed to warm to room temperature and stirred further for 30 min. The reaction m ixture was basified to pH 8 by slow addition of saturated sodium bicarbonate solution, extracted with chloroform. The combined organic layer was washed with water, dried over magnesium sulfate, and the solvent removed to give 2 (chloromethyl) 3 methoxypyri dine as a yellow crystals (70%), mp 75 76C; 1 H MNR (300 MHz, CDCl 3 3. 90 ( s 3 H), 4.7 6 (s, 2 H), 7. 20 7.2 8 ( m 2 H), 8.1 9 (d, J = 4. 2 Hz, 1H ) ; 13 C NMR (75

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62 MHz, CDCl 3 42.4 55.8 118.4 124.8 141. 2 146.1 154.1 Anal. Calcd. for C 7 H 8 Cl NO: C, 53.35 ; H, 5.12 ; N, 8.89 ; found: C, 52.90; H, 5.09 ; N, 8.41 3 .4. 12 Preparati on of 2 (3 M ethoxypyridin 2 yl)acetonitrile 3.52 2 (chloromethyl) 3 methoxypyridine ( 0.35 g, 2.25 mmol) and excess potassium cyanide (0.9 g, 13.5 mmol) were combined in dimethylformamide at room temperature and stirred for 18 h. Water (10 mL) and dichloro methane 10 mL) was added to the reaction mixture and stirred for 15 min. the phases were separated, and the water phase washed with dichloromethane. The combined organic phases were washed with water and dried over magnesium sulfate, filtered, and the filt erate evaporated to give 2 (3 methoxypyridin 2 yl)acetonitrile as orange crystals (27%), mp 63 65C; 1 H MNR (300 MHz, CDCl 3 ( s 3 H), 3.88 (s, 2 H), 7.16 7.28 ( m 2 H), 8.16 (d, J = 4.2 Hz, 1H ); 13 C NMR (75 MHz, CDCl 3 55.7 117.1 117.7 124. 4, 140.1 141.2 153.4 Anal. Calcd. for C 8 H 8 N 2 O: C, 64.85 ; H, 5.44 ; N, 18.91 ; found: C, 64.54 ; H, 5.32 ; N, 18.37 3 .4. 13 Preparation of (Z) N' Hydroxy 2 (3 m ethoxypyridin 2 yl)acetimidamide 3.53 To a solution of hydroxylamine hydrochloride (0.21 g, 3 mmo l) in water (10 mL) a solution of potassium carbonate ( 0.2 g, 1.5 mmol) in water (10 mL)was added gradually and then 30 mL of methanol Inorganic precipitate was removed by filtration. To the filtrate was added 2 (3 methoxypyridin 2 yl)acetonitrile (0.15 g 1 mmol) and the mixture was heated under reflux for 4 h. Removal of the solvent give crude (Z) N' hydroxy 2 (3 methoxypyridin 2 yl)acetimidamide as pale yellow oil (58%), which was used without further purification.

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63 3.4.14 Preparation of N (4 M ethoxypyra zolo[1,5 a]pyridin 2 yl)acetamide 3.28 and N A cetyl N (4 methoxypyrazolo[1,5 a]pyridin 2 yl)acetamide 3.54 (Z) N' H ydroxy 2 (3 methoxypyridin 2 yl)acetimidamide (1. 0 g 5.5 mmol) was dissolved in acetic anhydride and heated under reflux for 30 min. After the reaction was cooled down it was evaporated under reduced pressure.The residue was purified by column c h romatography ( hexane ethylacetate) to obtain 3.28 and 3.54. N (4 M ethoxypyrazolo[1,5 a]pyridin 2 yl)acetamide 3.28 White crystals (25%); mp 160 162 C ; HRMS (ESI) calc. for [C 10 H 11 N 3 O 2 +H] + 206.0924; Found: 206.0923; 1 H MNR (300 MHz, DMSO d 6 ) 2.07 (s, 3H), 3.90 (s, 3H), 6.60 (d, J = 7.7 Hz, 1H), 6.72 ( t, J = 7.2 Hz, 1H), 6.82 (s, 1H), 8.12 (d, J = 6.7 Hz, 1H), 10.75 (s, 1H) ; 13 C NMR (75 MHz, DMSO d 6 23.3, 55.7, 85.0, 100.4, 110.8, 121.1, 134.6, 148.8, 149.5, 168.0 N A cetyl N (4 methoxypy razolo[1,5 a]pyridin 2 yl)acetamide 3.5 4 Brown powder (9%); mp 142 144C; 1 H MNR (300 MHz, DMSO d 6 2.01 (s, 6H), 3.73 (s, 3H), 6.45 (s, 1H), 6.51 (d, J = 7.7 Hz, 1H), 6.69 (t, J = 7.4 Hz, 1H), 8.07 (d, J = 6.9 Hz, 1H) ; 13 C NMR (75 MHz, DMSO d 6 26.0, 55.9, 93.8, 100.8, 112.7, 121.6, 135.5, 148.0, 150.1, 172.1 Anal. Calcd. for C 12 H 13 N 3 O 3 : C, 58.29; H, 5.30; N, 16.99; found: C, 58.18; H, 5.36; N, 16.62.

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64 CHAPTER 4 SUMMARY OF ACHIEVEMENTS Synthetic organic chemistry plays an import ant role in the fields of material science, pharmaceuticals, cosmetics, food chemistry, and agricultures. The present work extends the scope of 1,3-dipolar cycloaddition in order to be able to obtain novel compounds for cosmetic use. Chapter 1 provides an overview of previ ous synthetic methods for the preparation of pyrrolo[1,2-b]pyrazine and pyrazo lo[1,5-a]pyridine. Pyrrolo[1,2b ]pyridazine is a N bridgehead aromatic heterocycl e containing two nitrogen at oms, formally obtained by the condensation of pyridazine and pyrrole. The first pyrrolo[1,2-b]pyridazine derivatives were synthesized by reacting pyridazine with acetylenic esters in 1956 by Letsinger and Lasco. [56JOC764] One of the other gener al synthetic methods for obtaining pyrroloazines having a nitrogen at om at the junction of the tw o heterocyclic moieties is the 1,3-dipolar cycloaddition between mesoi onic 1,3-oxazole-5-ones, also called munchnones, and acetylenic dipolarophiles. [64ACIE135, 08S813] In Chapter 2 novel, highly functionalized pyrrolo[1,2-b]pyridazines were prepared utilizing 1,3-dipolar cycloaddition between meso ionic 1,3-oxazole-5-ones and acetylenic dipolarophiles in acetic anhydride as reacti on medium at 90C. However, we were not able to obtain our final target; the unsuccessf ul reactions provided an insight into the chemical properties of py rrolopyridazine derivatives. In Chapter 3, novel, functionalized pyra zolo[1,5-a]pyridine derivatives were prepared. We were able to utiliz e 1,3-dipolar cycl oaddition between N -amino-pyridinium salts and an acetylenic dipolarophile in acet ic anhydride as reaction medium at 90C.

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65 However, we were not able to obtain all of our final targets; the unsuccessful reactions provided an insight into the chemical properties of pyrazolopyridine derivatives. Many methods are known to synthesize pyrrolo[1,2 b]pyrazin es and pyrazolo[1,5 a]pyridines; however the approach by 1,3 dipolar cycloaddition is new in the literature. By this work I was able to extend the scope of the cycloaddition reaction and successfully synthes e s new derivativ es of the pyrrolo[1,2 b]pyridazine and the pyrazolo[1,5 a]pyridine compound family.

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66 LIST OF REFERENCES The reference citation system employed throughout this research report is from (Eds. Katritzky, A. R.; Rees, C. W.; Scriven, E.). Each time a reference is cited, a number letter code is designated to the corresponding reference with the first two or four if the reference is er indicating the year followed by the letter code of the journal and the page number in the end. Additional notes to this reference system are as follows: 1) Each reference code is followed by conventional literature citation in the ACS style. 2) Journals which are published in more than one part including in the abbreviation cited the appropriate part. 3) Less commonly used books and journals are still abbreviated as using initials of the journal name. 4) Patents are given by their application number. 5 ) The list of the reference is arranged according to the designated code in the order of (i) year, (ii) journal/book in alphabetical order, (iii) part number or volume number if it is included in the code, and (iv) page number. REFERENCES [34JLAC129] Diels, O., Meyer, R. Justus Liebig Ann. Chem., 1934, 513, 129 [52JACS3222] Kinga, J. A.; Cmilla, F. M. J. Am. Chem. Soc., 1952, 74, 3222 [56JACS407] McMillan, F. H.; Kun, K. A.; McMillan, C. B.; Schwartz, B. S.; King, J. A. J. Am. Chem. Soc., 1956, 78, 407 [56JA CS2642] McMillan, F. H.; McMillan, C. B.; Kun, K. A.; King, J. A. J. Am. Chem. Soc., 1956, 78, 2642

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67 [56JOC764] Letsinger, R. L.; Lasco, R. J. Org. Chem., 1956, 21, 764 [62TL387] Huisgen, R.; Grashey, R.; Krischke, R. Tetrahedron Lett., 1962, 3, 387 [DE114 9496] Lange, F. W. 1963, Pat. App. DE1149496 [63ACIE633] Huisgen, R. Angew. Chem. Int. Ed., 1963, 2, 633 [64ACIE135] Huisgen, R.; Gotthardt, H.; Bayer, H. O. Angew. Chem. Int. Ed. 1964, 3, 135 [GB1026978] Schwarzkopf Verwaltung GmbH 1966, Pat. App. GB10269 78 [66JCS2218] Acheson, R. M.; Foxton, M. W. J. Chem. Soc. (C), 1966, 2218 [68AHC211] Tisler, M.; Stanovnik, B. Adv. Heterocycl. Chem. 1968 9 211. [68JOC2291] Heusgen, R. J. Org. Chem., 1968, 33, 2291 [68JOC3766] Potts, K. T.; Singh, U. P.; Bhattacha ryya, J. J. Org. Chem. 1968, 33, 3766 [GB1153196] Schwarzkopf Verwaltung GmbH 1969, Pat. App. GB1153196 [71CC226] Fried, F.; Taylor, J. B.; Westwood, R. Chem. Commun., 1971, 226 [71JOC2978] Sasaki, T.; Kanematsu, K.; Kakehi, A. J. Org. Chem., 1971, 36, 2 978 [72JOC3106] Sasaki, T.; Kanematsu, K.; Kakehi, A. J. Org. Chem., 1972, 37, 3106 [73CPB2146] Suzue, S.; Hirobe, M.; Okamoto, T. Chem. Pharm. Bull., 1973, 21, 2146 [73CR255] Mckillip, W. J.; Sedor, E. A.; Culbertson, B. M.; Wawzonek, S. Chem. Rev. 1973, 73, 255 [75JCSPT406] Tamura, Y.; Sumida, Y.; Miki, Y.; Ikeda, M. J. Chem. Soc. Perkin Trans., 1975, 406 [75JHC481] Tamura, Y.; Kim, J. H.; Miki, Y.; Hayashi, H.; Ikeda, M. J. Het. Chem. 1975, 12, 481 [75JMC741] Pifferi, G.; Parravicini, F.; Carpi, C.; Dori gotti, L. J. Med. Chem., 1975, 18, 741

PAGE 68

68 [77S1] Tamura, Y.; Minamikawa, J.; Ikeda, M. Synthesis, 1977, 1 [79AHC365] Tisler, M.; Stanovnik, B. Adv. Heterocycl. Chem., 1979 24 365. [80JCSCC1109] Tsuchiya, T.; Sashida, H. J. Chem. Soc. Chem. Commun. 1980, 1 109 [80JOC90] Potts, K. T.; Youzwak, H. P.; Zurawel Jr., S. J. J. Org. Chem., 1980, 45, 90 [81JHC1149] Anderson, P. L.; Hasak, J. P.; Kahle, A. D.; Paolella, N. A.; Shapiro, M. J. J. Het. Chem. 1981, 18, 1149 [DE3132885] Clausen, T. 1983, Pat. App. DE31328 85 [JP58140092] Okada, Y.; Satou, Y.; Kamei, K. 1983, Pat. App. JP58140092 [83T767] Barillier, D.; Strobel, M. P.; Morin, L.; Paquer, D. Tetrahedron, 1983, 39, 767 [DE3233540] Maak, N. 1984, Pat. App. DE3233540 [US4539507] Vanslyke, S. A.; Tamg, C. W. 1985 Pat. App. US4539507 [87APL913] Tang, C. W.; VanSlyke, S. A. Appl. Phys. Lett., 1987, 51, 913 [87T2557] Ballesteros, P.; Claramunt, R. M. Tetrahedron, 1987, 43, 2557 [89BKCS614] Lee, S. G.; Yoon, Y. J. Bull. Korean Chem. Soc., 1989, 10, 614 [89JOC3652] Wa dsworth, D. H.; Weidner, C. H.; Bender, S. L.; Nuttall, R. H.; Luss, H. R. J. Org. Chem., 1989, 54, 3652 [EP483836] Higashino, T.; Suzuki, Y.; Sasahara, T.; Saito, T.; Mochizuki, D. 1991, Pat. App. EP483836 [WO9118903] Matsuo, M.; Manabe, T.; Okumura, H.; Matsuda, H.; Fujii, N. 1991, Pat. App. WO9118903 [91DNP150] Andersen, P. H.; Nielsen, E. B. Drugs News Perspect 1991, 4, 150 [91N610] Van Tol, H. H. M.; Bunzow, J. R.; Guan, H. C.; Sunahara, R. K.; Seeman, P.; Niznik, H. B.; Civelli, O. Nature 1991, 350, 610 [93HMG767] Lichter, J. B.; Barr, C. L.; Kennedy, J. L.; Van Tol, H. H.; Kidd, K. K.; Livak, K. J. Hum. Mol. Genet. 1993, 2, 767

PAGE 69

69 [93JMVS2] Elion, G. B. J. Med. Virol. Suppl 1993, 1, 2 [93N441] Seeman, P.; Guan, H. C.; Van Tol, H. H. M. Nature 1993, 365 441 [94AJC991] Brown, R. F. C.; Eastwood, F. W.; Fallon, G. D.; Lee, S. C.; McGeary, R. P. Aust. J. Chem. 1994, 47, 991 [94N739] Lee, J. C.; Laydon, J. T.; McDonnell, P. C.; Gallagher, T. F.; Kumar, S.; Green, D.; McNulty, D.; Blumenthal, M. J.; Heys, J. R.; Landvatter, S. W.; Strickler, J. E.; McLaughlin, M. M.; Siemens, I. R.; Fisher, S. M.; Livi, G. P. l.; White, J. R.; Adams, J. L.; Young, P. R. Nature 1994, 372, 739 [96JLB152] Lee, J. C.; Young, P. R. J. Leukocyte Biol. 1996, 59, 152 [96MC1941] Kulag owski, J. J.; Broughton, H. B.; Curtis, N. R.; Mawer, I. M.; Ridgill, M. P.; Baker, R.; Emms, F.; Freedman, S. B.; Marwood, R.; Patel, S.; Patel, S.; Ragan, C. I.; Leeson, P. D. Med. Chem. 1996, 39, 1941 [97APF69] Ungureanu, M.; Mangalagiu, I. I.; Grosu, G .; Petrovanu, M. Ann. Pharm. Fr., 1997, 55, 69 [US5773476] Chen, H.; Gazit, A.; Levitzki, A.; Hirth, K. P.; Mann, E.; Shawver, L. K.; Tsai, J.; Tang, P. C. 1998, Pat. App. US5773476 [98BMCL1829] Nasir, A. I.; Gundersen, L. L.; Rise, F.; Antonsen, O,; Krist ensen, T.; Langhelle, B.; Bast, A.; Custers, I,; Haenen, G. R. M. M.; Wikstrom, K. Bioorg. Med. Chem. Lett., 1998, 8, 1829 [98CCR161] Chen, C. H.; Shi, J. Coord. Chem. Rev., 1998, 171, 161 [EP1085021A1] Ohtani, M.; Fuji, M.; Fukui, Y.; Adachi, M. 1999, Pat App. EP1085021A1 [WO9935146] Carter, M. C.; Cockerill, G. S.; Guntrip, S. B.; Lackey, K. E.; Smith, K. J. 1999, Pat. App. WO9935146 [99APF415] Dima, S.; Caprosu, M.; Ungureanu, M.; Grosu, G.; Petrovanu, M. Ann. Pharm. Fr., 1999, 57, 415 [99JMC2183] Cheng Y.; Ma, B.; Wudl, F. J. Mater. Chem., 1999, 9, 2183 [00DF587] Hrib, N. J. Drugs Future 2000, 25, 587

PAGE 70

70 [00MP531] McCracken, J. T.; Smalley, S. L.; McGough, J. J.; Crawford, L.; Mol. Psychiatry 2000, 5 531 [WO2001035917] Birault, V.; Leduc, M.; Terranova, E. 2001, Pat. App. WO2001035917 [01FV2381] Roizman, B.; Pellett, P. E.. In Knipe, D. M., Howley, P. M., Eds.; Fields Virology ; Lippincott Williams and Wilkins: Philadelphia, PA, 2001, 2, 2381 [01H23] Roizman, B.; Whitley, R. J. Herpes 2001, 8, 23 [01JID196] Spruance, S. L.; Tyring, S. K.; Smith, M. H.; Meng, T. C. J. Infect. Dis. 2001, 184, 196 [WO2002076416] Kravtchenko, S.; Lagrange, A. 2002, Pat. App. WO2002076416 [WO2002076417] Kravtchenko, S.; Lag range, A. 2002, Pat. App. WO2002076417 [WO2002076418] Kravtchenko, S.; Lagrange, A. 2002, Pat. App. WO2002076418 [WO2002076419] Kravtchenko, S.; Lagrange, A. 2002, Pat. App. WO2002076419 [02BMCL633] Lober, S.; Aboul Fadl, T.; Hubner, H.; Gmeiner, P. Bioorg Med. Chem. Lett., 2002, 12, 633 [02CR2357] Kido, J.; Okamoto, Y. Chem. Rev., 2002, 102, 2357 [02NM392] Kleymann, G.; Fischer, R.; Betz, U. A. K.; Hendrix, M.; Bender, W.; Schneider, U.; Handke, G.; Eckenberg, P., et al. Nat. Med. 2002, 8, 392 [02RMV167] Wathen, M. W. Rev. Med. Virol. 2002, 12, 167 [WO03082208] Salvati, M. E.; Barbosa, S. A.; Chen, Z.; Hunt, J. T. 2003, Pat. App. WO03082208 [WO2003078435] Fu, J. M. 2003, Pat. App. WO2003078435 [03ERAT283] Moomaw, M. D.; Cornea, P.; Rathbun, R. C.; Wendel, K. A. Expert Rev. Anti infect. Ther 2003, 1, 283 [03JOC7119] Legault, C.; Charette, A. B. J. Org. Chem. 2003, 68, 7119 [US20040209886] Salvati, M. E.; Illig, C. R.; Wilson, K. J.; Chen, J.; Meegalla, S. K.; Wall, M. J. 2004, Pat. App. US20040209886

PAGE 71

71 [WO200 4009596] Brown, M. L.; Cheung, M.; Dickerson, S. H.; Drewry, D. H.; Lackey, K. E.; Peat, A. J.; Thompson, S. A.; Veal, J. M.; Wilson, J. L. R. 2004, Pat. App. WO2004009596 [WO2004009597] Dickenson, S. H.; Garrido, D. M.; Mills, W. Y.; Kano, K.; Peat, A. J. ; Thompson, S. A.; Wilson, J. L. R.; Zhou, H. 2004, Pat. App. WO2004009597 [WO2004009602] Brown, M. L.; Cheung, M.; Dickerson, S. H.; Garrido, D. M.; Mills, W. Y.; Miyazaki, Y.; Peat, A. J.; Peckham, J. P.; Swalley, T. L.; Thompson, S. A.; Veal, J. M.; Wil son, J. L. R. 2004, Pat. App. WO2004009602 [WO2005013907] Fox, B. M.; Iio, K.; Inaba, T.; Kayser, F.; Li, K.; Sagawa, S.; Tanaka, M.; Yoshida, A. 2005, Pat. App. WO2005013907 [WO2005097952] Glenn, R. W. Jr.; Lim, M.; Gardlik, J. M.; Murphy, B. P.; Rees, C. 2005, Pat. App. WO2005097952 [05BMC5346] Gudmundsson, K. S.; Johns, B. A.; Wang, Z.; Turner, E. M.; Allen, S. H.; Freeman, G. A.; Boyd, F. L. Jr.; Sexton, C. J.; Selleseth, D. W.; Monirib, K. R.; Creech, K. L. Bioorg. Med. Chem. 2005, 13, 5346 [05CTMC101 7] Goldstein, D. M.; Gabriel, T. Curr. Top. Med. Chem. 2005, 5, 1017 [05H1871] Caprosu, M.; Butnariu, R.; Mangalagiu, I. I. Heterocycles, 2005, 65, 1871 [05JMC5771] Elsner, J.;Boeckler, F.; Heinemann, F. W.; Hubner, H.; Gmeiner, P. J. Med. Chem. 2005, 48, 5771 [05M4698] Mitsumori, T.; Craig, I. M.; Martini, I. B.; Schwartz, B. J.; Wudl, F. Macromolecules, 2005, 38, 4698 [05T10227] Swamy, K. M K.; Park, M. S.; Han, S. J.; Kim, S. K.; Kim, J. H.; Lee, C.; Bang, H.; Kim, Y.; Kima, S. J.; Yoon, J. Tetrahedron, 2005, 61, 10227 [WO2006039990] Speckbacher, M.; Braun, H. J. 2006, Pat. App. WO2006039990A1 [06BMC944] Allen, S. H.; Johns, B. A.; Gudmundsson, K. S.; Freeman, G. A.; Boyd, F. L. Jr.; Sexton, C. H.; Selleseth, D. W.; Creech, K. L.; Moniri, K. R. Bioorg. Me d. Chem. 2006, 14, 944

PAGE 72

72 [06CTMC113] Peifer, C.; Wagner, G.; Laufer, S. Curr. Top. Med. Chem 2006, 6, 113 [06EOP2271] Vinh, D. C.; Aoki, F. Y. Expert Opin. Pharmacother 2006, 7, 2271 [06MRR1] Wagner, G.; Laufer, S. Med. Res. Rev 2006, 26 1 [06S804] Zbanc ioc, G. N.; Mangalagiu, I. I. Synlett, 2006, 804 [EP1847250A1] Pasquier, C.; Buclin, V.; Roulin, A.; Braun, H. J. 2007, Pat. App. EP1847250A1 [WO2007065664] Imbach, P.; Holzer, P.; Furet, P. 2007, Pat. App. WO2007065664 [07BMCL2858] Johns, B. A.; Gudmundss on, K. S.; Allen, S. H. Bioorg. Med. Chem. Lett. 2007, 17, 2858 [07ARKIVOC180] Darehkordi, A.; Saidi, K.; Islami, R. I. ARKIVOC, 2007, (i), 180 [07JHC1149] Butnariu, R. M.; Caprosu, M. D.; Bejan, V.; Ungureanu, M.; Poiata, A.; Tuchilus, C.; Florescu, M.; M angalagiu, I. I. J. Het. Chem., 2007, 44, 1149 [07PT192] Clark, J. E.; Sarafraz, N.; Marber, M. S. Pharmacol. Ther. 2007, 116, 192 [EP2090576] Merz Pharma GmbH & Co. 2008, Pat. App. EP2090576 [FR2934592] Vidal, L.; Fadli, A.; Metais, E.; Katritzky, A. R. 2 008, Pat. App. FR2934592 [WO2008113559] Gmeiner, P.; Huebner, H.; Skultety, M. 2008, Pat. App. WO2008113559 [08ARKIVOC232] Dumitrascu, F.; Dumitrescu, D. G. ARKIVOC, 2008, (i), 232 [08BMCL5428] Cheung, M.; Harris, P. A.; Badiang, J. G.; Peckham, G. E.; Cha mberlain, S. D.; Alberti, M. J.; Jung, D. K.; Harris, S. S.; Bramson, N. H.; Epperly, A. H.; Stimpson, S. A.; Peel, M. R. Bioorg. Med. Chem. Lett. 2008, 18, 5428 [08S813] Dumitrascu, F.; Caira, M. R.; Draghici, B.; Caproiu, M. T.; Dumitrescu, D. G. Synlett 2008, 813 [DE102008061676] Goutsis, K.; Sunger, G. 2009, Pat. App. DE102008061676 [10T278] Zbancioc, G. N.; Mangalagiu, I. I. Synlett, 2010, 278

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73 BIOGRAPHICAL SKETCH Judit Kovacs, first daughter of Dr. Pe ter Kovacs and Zsuzsanna Gyulai, was born in Hungary. She received her Master of Science in chemistry from Eotvos Lorand University of Science, Hungary, in July 2007. During her entire study, she worked as a researcher intern with AMRI (formerly known as ComGenex) in a synthetic organic chemistry lab focused on combinatorial chem istry, library synthesis, and pilot study. During her fifth year, she worked as a undergraduate researcher in the Hungarian Academy of Science Chemical Research Cent er Institute of Biom olecular Chemistry Laboratory of Natural Organic Compounds under the supervision of Dr. Gabor Dornyei, working on the total synthesis of epiqu inamide. Upon graduation, she joined the University of Florida as an adjunct assistant in chemistry under the supervision of Prof. Alan R. Katritzky. She continued her education at the Department of Chemistry, University of Florida, from August 2008. Her masters research focused on synthesis of heterocycles supervised by Dr. Alan R. Katritzky.