SYNTHESIS OF BIOLOGICALLY ACTIVE NATURAL PRODUCTS AND PHARMACOLOGICALLY ACTIVE MOLECULES BY COMBINATORIAL CHEMISTRY A THESIS Submitted to the SHIVAJI UNIVERSITY, KOLHAPUR For the Degree of DOCTOR OF PHILOSOPHY in CHEMISTRY Science Faculty By ANIL M. DESHPANDE Under the Guidance of Dr. A. A. NATU Division of Organic Chemistry (Synthesis) National Chemical Laboratory Pune 411 008 SEPTEMBER 2001 DEDICATED To My Parents For Their Warmth, Humor And Ethics CERTIFICATE This is to certify that the thesis entitled “SYNTHESIS OF BIOLOGICALLY ACTIVE NATURAL PRODUCTS AND PHARMACOLOGICALLY ACTIVE MOLECULES BY COMBINATORIAL CHEMISTRY” which is being submitted herewith for the award of the Degree of Philosophy in Chemistry of Shivaji University, Kolhapur is the result of the original research work completed by Mr. Anil M. Deshpande under my supervision and guidance at the National Chemical Laboratory, Pune and to the best of my knowledge and belief the work embodied in this thesis has not formed earlier the basis for the award of any Degree or similar title of this or any other University or examining body. (A. A. Natu) Research Guide September 2001 Scientist, Division of Organic Chemistry (Synthesis) National Chemical Laboratory Pune 411 008. DECLARATION I hereby declare that the thesis entitled “SYNTHESIS OF BIOLOGICALLY ACTIVE NATURAL PRODUCTS AND PHARMACOLOGICALLY ACTIVE MOLECULES BY COMBINATORIAL CHEMISTRY” completed and written by me has not previously formed the basis for the award of any Degree or Diploma or other similar title of this or any other University or examining body. (Anil M. Deshpande) Division of Organic Chemistry (Synthesis) September 2001 National Chemical Laboratory Pune 411 008. ACKNOWLEDGEMENTS I wish to express my wholehearted gratitude to my research supervisor Dr. A. A. Natu for his masterly guidance, invaluable suggestions and perceptive criticism while carrying out the present work. His untiring enthusiasm, moral support, kind care and help out of the way lead me to overcome all the difficulties I met during this endeavor. I owe tremendous debt to Dr. N. P. Argade for his scientific guidance, earnest suggestions and encouragement extended to me in this work. I am indebted for his kind care and concern in the laboratory. It is my privilege to thank Dr. K. N. Ganesh, Head OCS Division, for his constant encouragement and keen interest shown during the progress of the work. Thanks are due to the Director, NCL for providing the infrastructure and necessary facilities. I take this opportunity to thank Dr. Suresh Iyer, Dr. S. D. Sathye, Dr. U. V. Desai and Dr. C. E. Deshpande for their help and encouragement during this work. I am extremely thankful to Dr. Ralph T. Scannell and Mr. Joseph Eckman from CytoMed, Inc. Cambridge, USA, for biological evaluation of chalcones which otherwise would have been a difficult task. The work would have not completed without the help provided by the analytical groups. My sincere thanks to Mr. A. G. Samuel, Mrs. U. D. Phalgune, Mr. V. T. Sathe and Rupali for providing the NMR training as well as for recording the spectra. I would like to thank Mrs. Shantakumari and Mrs. Kale for their help in recording the Mass and IR spectra and all the library staff for providing documentation and repographical facilities. My special thanks to lab-friends Dr. Vallabh, Mangaleswaran, Santosh, Anirban, Easwar, and Mukulesh for their cheerful co-operation and the help in every aspect through out this work. My heartfelt thanks are due to my friends Dr. C. Ramesh, Vinay, Milind, Dr. Nandanan, Dr. Saravanan, Dr. Godwin, Dr. Manish, Dr. Sandeep, Suresh, Sachin and Vinayak for their friendly suggestions and timely help making my stay at NCL very comfortable and memorable one. I would like to extend my thanks to Jayanthi, Vidyesh, Girish, Mandar, and my colleagues at Kolhapur University, Mr. V. B. Helvi, B. V. Tamhankar, P. P. Kulkarni and so many friends who helped me during this work. I thank Mr. T. Patil, Mr. P. Pawar, Mr. P. Khandekar for their help. I sincerely acknowledge CSIR, New Delhi, for the award of research fellowship. Finally, no words can express the feelings towards my parents and family members, who have contributed and sacrificed a lot to reach me at this stage and will always remain a sole source of inspiration in my life. GENERAL REMARKS All the solvents used were purified according to the literature procedures. Petroleum ether used in the experiments is of 60-80 °C boiling range. TLC was performed on E- Merck pre-coated 60 F254 plates and the spots were rendered visible by exposing to UV light, iodine, phosphomolybdic acid (in ethanol), bromocresol green (in ethanol). Column chromatographic separations were carried out by gradient elution with light petroleum ether-ethyl acetate mixture, unless otherwise mentioned and silica gel (60-120 mesh/100- 200 mesh). The experimental procedures for preparation of starting materials has not been included in the experimental section and references have been cited at the appropriate places. IR spectra were recorded on Shimadzu FTIR instrument, for solid either as nujol mull or in chloroform solution (conc. 1 mM) and neat in case of liquid compounds. NMR spectra were recorded on either Brucker ACF 200 (200 MHz for 1H NMR and 50 MHz for 13C NMR) or MSL 300 (300 MHz for 1H NMR and 75 MHz for 13C NMR) spectrometers. Chemical shifts (d) reported are referred to internal reference tetramethyl silane. Mass spectrums were recorded on Finning-Mat 1020C mass spectrometer and are obtained at an ionization potential of 70 eV. Microanalytical data were obtained using a Carlo-Erba CHNS-O EA 1108 Elemental Analyser. Elemental analyses observed for all the newly synthesized compounds were within the limits of accuracy. HPLC was performed on Hwlett Pacckard instrument using C-18 reverse phase column and diodearray UV detector. All the melting points reported are uncorrected and were recorded using an electro-thermal melting point apparatus. All the compounds previously known in the literature were characterized by comparison of their Rf values on TLC, IR and NMR spectra as well as melting point (in case of solid) with authentic samples. Biological evaluation of all combinatorial mixtures and individual compounds were carried at CytoMed, Inc. Cambridge, USA. All results are mean of duplicate and in most cases triplicate determination. CONTENTS PUBLICATIONS i ABSTRACT ii ABBREVIATION ix CHAPTER ONE CONCISE ACCOUNT ON CHEMISTRY OF DIALKYLSUBSTITUTED MALEICANHYDRIDES 1.1 Introduction 1 1.1.1 Maleic Anhydride Derivatives and their 1 Applications 1.1.2 Synthetic Utility of Methyl and Dimethylmaleic 2 Anhydride 1.2 Alkylmethylmaleic Anhydride 4 1.2.1 Dimethylmaleic Anhydride 7 1.2.2 Tetradecylmethylmaleic Anhydride: 9 Chaetomellic Anhydride A 1.2.3 Tyromycin A 20 1.2.4 2,3-Disubstituted Maleic Anhydride 23 Segment of Tautomycin 1.2.5 Telfairic Anhydride and Related 30 Compounds 1.3 Nonadride and Dialkyl/Diaryl Substituted Derivatives 31 of Maleic Anhydride 1.4 Summary 36 1.5 References 37 CHAPTER TWO SYNTHESIS OF BIOACTIVE NATURAL PRODUCTS 44 AND NEW HETEROCYCLES SECTION A 45 Chemoselective Carbon-Carbon Coupling of Organocuprates with (Bromomethyl)methylmaleic Anhydride Synthesis of Chaetomellic Acid A 2.1.1 Background 45 2.1.2 Present Work 48 2.1.3 Results and Discussion 49 SECTION B 52 A Facile Synthesis of (±)-2,3-Disubstituted Maleic Anhydride Segment of Antifungal Antibiotic Tautomycin 2.2.1 Background 52 2.2.2 Present Work: Results and Discussion 54 SECTION C 59 Synthesis of 2,3-Didehydrotelfairic Anhydride 2.3.1 Backgropund 59 2.3.2 Present Work: Results and Discussion 59 SECTION D 68 Synthesis of a -Quinoxalinylacrylic and a - Benzothiazinylacrylic Acids 2.4.1 Background 68 2.4.2 Present Work: Results and Discussion 71 2.5 Conclusions 77 2.6 Experimental Part of Section A to D 79 2.7 Tabulated Spectral Data for Compounds in 89 Section A to D 2.8 References of Section A to D 136 CHAPTER THREE SYNTHESIS AND SCREENING OF NAPHTHALENE SUBSTITUTED CHALCONES AS LEUKOTRIENE B4 INHIBITORS: A COMBINATORIAL APPROACH Introduction 142 3.1 A Combinatorial Approach 142 3.2 Anti-inflammatory Agents 145 3.2.1 Arachidonic Acid Cascade 147 3.2.2 Mechanism of Action of 5-Lo and Biosynthesis 148 of Leukotrienes (LTs) 3.2.3 Physiological Role and Receptors of Leukotrienes 151 3.2.4 5-Lipoxygenase (5-Lo) a Target for Drug 152 Development 3.3 Synthetic 5-Lo Inhibitors 153 3.3.1 Substrate and Product Analogues 153 3.3.2 Phenolic Compounds 154 3.3.3 Heterocyclic Compounds 155 3.3.4 Hydroxamic Acid and Related Compounds 155 PRESENT WORK 158 3.4 Rational in Designing the Naphthalene Substituted 158 Chalcones 3.5 Synthesis and Biological Evaluation of Combinatorial 162 Library of Naphthalene Substituted Chalcones 3.5.1 Chemistry 162 3.5.2 Library Generation 164 3.5.3 Biological Evaluation 166 3.6 Results and Discussion 167 3.7 Summary 170 3.8 Experimental 172 3.9 Tabulated Spectral Data 174 3.10 References 181 ERRATUM 187 LIST OF PUBLICATIONS (1) Chemoselective carbon-carbon coupling of organocuprates with (bromomethyl)methylmaleic anhydride : Synthesis of Chaetomellic acid A A. M. Deshpande, A. A. Natu and N .P. Argade J. Org. Chem. 1998, 63, 9557. (2) Synthesis and screening of a combinatorial library of naphthalene substituted chalcones : Inhibitors of leukotriene B4 A. M. Deshpande, N. P. Argade, A. A. Natu and J. Eckman. Bioorg. Med. Chem. 1999, 7, 1237. (3) Chemo- and regioselective nucleophilic reactions of (bromomethyl) methylmaleic anhydride : Synthesis of a-quinoxalinyl- and a-benzothiazinyl acrylic acids A. M. Deshpande, A. A. Natu and N. P .Argade Heterocycles, 1999, 51, 2159. (4) A facile synthesis of (±)-2,3-disubstituted maleic anhydride segment of Tautomycin A. M.