University of New Orleans ScholarWorks@UNO University of New Orleans Theses and Dissertations Dissertations and Theses 8-7-2003 Development of Novel Nicotinic Receptor Mediated Therapeutic Agents: Synthesis and Biological Evaluation of Novel Epibatidine Analogs and the First Total Synthesis of Anabasamine and Related Analogs Stassi DiMaggio University of New Orleans Follow this and additional works at: https://scholarworks.uno.edu/td Recommended Citation DiMaggio, Stassi, "Development of Novel Nicotinic Receptor Mediated Therapeutic Agents: Synthesis and Biological Evaluation of Novel Epibatidine Analogs and the First Total Synthesis of Anabasamine and Related Analogs" (2003). University of New Orleans Theses and Dissertations. 40. https://scholarworks.uno.edu/td/40 This Dissertation is protected by copyright and/or related rights. It has been brought to you by ScholarWorks@UNO with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Dissertation has been accepted for inclusion in University of New Orleans Theses and Dissertations by an authorized administrator of ScholarWorks@UNO. For more information, please contact [email protected]. DEVELOPMENT OF NOVEL NICOTINIC RECEPTOR MEDIATED THERAPEUTIC AGENTS: SYNTHESIS AND BIOLOGICAL EVALUATION OF NOVEL EPIBATIDINE ANALOGS AND THE FIRST TOTAL SYNTHESIS OF (±)-ANABASAMINE AND RELATED ANALOGS A Dissertation Submitted to the Graduate Faculty of the University of New Orleans in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Chemistry by Stassi C. DiMaggio B.S., Tulane University, 1998 August 2003 Dedicated to: My mother, Vita O. DiMaggio ii ACKNOWLEDGEMENTS I would like to express my sincere gratitude to my advisor, Professor Mark L. Trudell, for his guidance, support, and encouragement. His confidence helped me to stay focused on my goals. I would also like to thank my committee members, Professor Branko Jursic, Professor John Wiley, Professor Guijun Wang, and Professor Steven Rick. In addition, I would like to thank Professor Bruce C. Gibb for always taking the time to answer any questions I have had as well as Dr. Matthew Tarr and Dr. Paul Hanson. Dr. Stacey Lomenzo deserves acknowledgement for teaching me many invaluable techniques, as does Corinne Gibb for her assistance with the NMR. Thank you to Professor Edwin D. Stevens for the X-Ray crystallography data, Professor Lazlo Gyermek, at Harbor U.C.L.A. Medical Center, Professor Sari Izenwasser at the University of Miami for the in vitro and in vivo biological data, and Dr. Chau Wen Chou for the mass spectrometry analysis. I am also grateful for the Louisiana Board of Reagents and the National Institute on Drug Abuse (DA 12703) for financial support. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS………………………………………………………………iii TABLE OF CONTENTS…………………………………………………………………iv LIST OF TABLES………………………………………………………………………..vi LIST OF FIGURES……………………………………………………………………...vii ABSTRACT……………………………………………………………………………...ix INTRODUCTION…………..…………………………………………………………….1 Neuronal Nicotinic Acetylcholine Receptors (nAChRs)………………………………...1 Nicotinic Acetylcholine Receptor Structure and Subtype……………………………….2 α4β2 Function in the Mammalian Brain……………………………………….…….….9 Inhibition Constants and Effective Concentration………………………………...…...13 Epibatidine……………………………………………………………………….……..14 Structure-Activity Relationships of Epibatidine at the Nicotinic Receptor…………....17 Structure-Activity Relationships of Nicotine Related Analogs……...…………………22 Structure-Activity Relationships of 7-Azabicyclo[2.2.1]heptane Pyridyl Ethers…...…24 Structure-Activity Relationships of N-substituted 7-Azabicyclo[2.2.1]heptanes…...…29 The Nicotine Receptor Pharmacophore Model….……………………………………...30 Rigid Acetylcholine Analogs…………..……...………………………………………..34 Specific Aims and Design Strategy of Epibatidine Analogs…….....………..…….……36 iv Specific Aims and Design Strategy of Rigid Acetylcholine Analogs……………..…...39 Natural Product Synthesis: (±)-Anabasamine…………………………………………..41 Specific Aims And Design Rational of Anabasamine and Related Analogs…………...43 RESULTS AND DISCUSSION…………………………………………………………46 Attempted Synthesis with Acetyl Protecting Group……………………………………46 Attempted Synthesis with Tosylate Protecting Group………………………………….49 Attempted Synthesis with Boc Protecting Group………………………………………52 Synthesis of 1-(Pyridyloxymethyl)-7-azabicyclo[2.2.1.]heptanes……………………..56 Internitrogen Distances…………………………………………………………………67 Stereoselective Synthesis of Rigid Acetylcholine Analogs…………………………….69 Binding Affinity……………………………………………………………...………...74 Synthesis of (±)-Anabasamine and Nicotine Related Analogs………………………....79 CONCLUSION……………………………………………………..……………………87 EXPERIMENTAL……………………………………………………………………….90 REFERENCES…………………………………………………………………………121 APPENDEX………………………………………………………….…………………130 VITA……………………………………………………………………………………143 v LIST OF TABLES Table 1. Nicotinic Acetylcholine Receptor Subtypes…………………………………...10 Table 2. Nicotinic Ligand Binding at the Central Nervous System nAChR..…………..75 Table 3. Acetylcholine like Potency in Isolated Guinea Pig Ileum……………………..76 Table 4. Acetylcholine like Potency in Isolated Rat Jejunum…………………………..76 Table 5. Rat Blood Pressure Tests………………………………………………………77 vi LIST OF FIGURES Figure 1. Pentameric transmembrane nAChR; ion channel surrounded by subunits…….4 Figure 2. Trans-membrane M1-M4 helices………………………………………………6 Figure 3. M2 helices surrounding the ion channel of the receptor……………………….7 Figure 4. The Beers and Reich pharmacophore model………………………………….31 Figure 5. Comparison of the Beers and Reich model with the Sheridan model………...32 Figure 6. Superimposed structures of Epibatidine and Nicotine………………………..33 Figure 7. ORTEP Drawing of 146c……………………………………………………..63 Figure 8. ORTEP Drawing of 146d……………………………………………………..64 Figure 9. Chem3D Drawing of 155………………………………………………… ….68 Figure 10. Chem3D Drawing of 154………………...…………………………………..69 vii ABSTRACT In an effort to search for a more selective, less toxic neuronal nicotinic acetylcholine receptor analgesic agent in comparison to epibatidine, a series of analogs with hybrid structures of epibatidine and ABT-594 were designed and synthesized. The 1-(pyridyloxymethyl)-7-azabicyclo[2.2.1]heptane ring systems were furnished via an intramolecular cyclization from a trans 1,4 disubstitituted amino-cyclohexane derivative. The functionalized cyclohexane ring was formed via a [4+2] Diels-Alder cyclization reaction between the acetamidoacrylate and Danishefsky’s diene. These 1- (pyridyloxymethyl)-7-azabicyclo[2.2.1]heptane ring systems were then tested in vitro as potential α4β2 nicotinic acetylcholine receptor ligands with high potency and selectivity. In addition, a series of rigid acetylcholine analogs were synthesized from cocaine to study the conformation of acetylcholine, the endogenous neurotransmitter at the nicotinic acetylcholine receptor. A stereoselective reduction of 2-tropinone led to the enantioselective synthesis of the desired acetoxytropane systems. These compounds were also tested in in vivo models for binding affinity and efficacy responses. Anabasamine, an alkaloid isolated from the Central Asian shrub, Anabasis aphylla, was synthesized for the first time. It was targeted due to interesting preliminary biological activity such as exhibiting anticholinesterase activity, anti-inflammatory activity, and facilitated an increase in hepatic alcohol dehydrogenase levels. Only preliminary studies were performed as anabasamine is limited in quantity due to its viii difficult isolation. A versatile synthetic methodology was developed for the synthesis of anabasamine and related nicotine analogs. This new methodology employed a pyridyl anion addition to valerolactone, for anabasamine, or butyrolactone for the nicotine analog, to afford 5-hydroxy-1-(6-methoxy-pyridin-3-yl)-pentan-1-one or 4-hydroxy-1-(6- methoxy-pyridin-3-yl)-butan-1-one, respectively. A reductive amination provided the piperidine ring moiety and a Suzuki coupling reaction introduced the bipyridyl moiety to anabasamine in five steps and 23% overall yield. In addition, this methodology was applied successfully to the synthesis of nicotine and other related analogs. In particular the synthesis of 6-methoxynicotine, a useful drug intermediate, was generated improving the yield from 16% over five steps to 54% over three steps. ix 1 INTRODUCTION Nicotinic Acetylcholine Receptors (nAChRs) Though the nicotinic acetylcholine receptor (nAChR) was one of the first receptors to be cloned, its full mechanistic function is still elusive to scientists today. Its importance however is greatly appreciated. A progressive understanding of the active site has led to advances in formulating treatment for a variety of devastating central nervous system disorders. Additionally, understanding the binding mechanism of human nicotinic agonists and antagonists will lead the way to new nAChR drug discovery. Studying the active site of a receptor whose three-dimensional topology is unknown requires a multifaceted approach. One method is to carefully design molecules that incorporate the structural qualities of known biologically active compounds to achieve increasingly greater receptor potency. Such hybrids should take into account