Studies Toward the Total Synthesis of Trocheliophorolide a Stephanie Dorn
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Rochester Institute of Technology RIT Scholar Works Theses Thesis/Dissertation Collections 2011 Studies toward the total synthesis of Trocheliophorolide A Stephanie Dorn Follow this and additional works at: http://scholarworks.rit.edu/theses Recommended Citation Dorn, Stephanie, "Studies toward the total synthesis of Trocheliophorolide A" (2011). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by the Thesis/Dissertation Collections at RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. Studies Toward The Total Synthesis of Trocheliophorolide A Stephanie C.M. Dorn Submitted in Partial Fulfillment of the Requirements for the Master of Science in Chemistry Department of Chemistry College of Science Rochester Institute of Technology Rochester, NY 2011 Approved: Christina G. Collison, Ph.D. Project Advisor L. Paul Rosenberg, Ph. D. Department Chair Copyright Release Form Studies Toward the Total Synthesis of Trocheliophorolide A I, Stephanie C. M. Dorn, hereby grant permission to the Wallace Memorial Library of RIT, to reproduce my thesis in whole or in part. Any use will not be for commercial use or for profit. Signature Date 2 Acknowledgements I would like to thank my advisor, Dr. Christina Collison, for her professional and personal guidance, patience, support and encouragement throughout my time as a graduate student in the M.S. Program at RIT. Without her, I would not have had the opportunities and not be as well prepared for a doctoral program as I am now. I would also like to express gratitude to my thesis committee: Dr. Jeremy Cody, Dr. Thomas Kim, and Dr. Thomas Smith for their time and valuable suggestions. I would also like to thank Jennifer Swartzenberg, an undergraduate research student on this project, as she provided much work towards the cyclization of the butenolide coupling partner. I would like to thank the Department of Chemistry at RIT for financial support through teaching assistantships and a summer stipend, and also the stockroom staff who provided materials for the teaching labs and for my research lab. I would like to express my deepest thanks and affection to my family, for emotional support and words of wisdom during difficult times of this journey. To my mother, father, Sophie, Philip, Mémé, Pépé, Grandma, Grandpa, Grandmère, and all our wonderful pets—I love you always. Thank you all very much for your contribution and participation in this important chapter of my life. 3 Abstract Transition metal-mediated carbon-carbon bond forming reactions are among the most synthetically useful chemical transformations in modern organic synthesis. The most expedient routes toward many natural products and compounds of pharmacological interest involve such reactions. Our research focuses on the development of a novel synthetic route towards the total synthesis of the novel antibacterial natural product trocheliophorolide A using such transition metal-mediated reactions. Specifically, trocheliophorolide A was envisioned to be synthesized via a Stille coupling between a butenolide and an unsaturated sidechain. The butenolide synthesis was optimized and several routes to synthesize the sidechain were investigated. This thesis will detail the ongoing synthesis of trocheliophorolide A using a Wittig reaction rather than the previously envisioned Corey-Fuchs reaction, as well as suggestions towards the completion of the total synthesis. Trocheliophorolide A 4 Abbreviations 1H-NMR ...................................................proton NMR 13C-NMR ..................................................carbon-13 NMR Ac .............................................................acyl AcOH .......................................................acetic acid Boc ...........................................................tert-butyloxycarbonyl Bu .............................................................butyl Bu3SnH ....................................................tributyltin hydride C ...............................................................Celsius DHP..........................................................dihydropyran DIBAL-H .................................................diisobutylaluminum hydride DMAP ......................................................4-dimethylaminopyridine DMF .........................................................dimethylformamide DMSO ......................................................dimethylsulfoxide Et ..............................................................ethyl Et3N ..........................................................triethylamine EtO2CCl ...................................................ethyl chloroformate EtOAc ......................................................ethyl acetate eq ..............................................................equivalent(s) g................................................................gram(s) GC-MS .....................................................gas chromatography – mass spectrometry h................................................................hour(s) Hex ...........................................................hexanes HF-pyr ......................................................hydrogen fluoride – pyridine complex Hz .............................................................hertz L ...............................................................ligand LC-MS .....................................................liquid chromatography – mass spectrometry LDA .........................................................lithium diisopropylamide mp ............................................................melting point Me ............................................................methyl MHz .........................................................megahertz 5 min ...........................................................minute(s) mL ............................................................milliliter mol ...........................................................mole NaHMDS .................................................sodium hexamethyldisilazide n-BuLi ......................................................n-butyllithium NMR ........................................................nuclear magnetic resonance PCC ..........................................................pyridinium chlorochromate Pd(PPh3)4..................................................tetrakis(triphenylphosphine)palladium(0) Pd(PPh3)Cl2 ...................................................................dichlorobis(triphenylphosphine)palladium(II) Ph .............................................................phenyl PPh3 ..........................................................triphenylphosphane p-TsCl ......................................................para-toluenesulfonyl chloride p-TsOH ....................................................para-toluenesulfonic acid RT ............................................................room temperature Sat ............................................................saturated TBS ..........................................................tert-butyldimethylsilyl Tf ..............................................................trifluoromethanesulfonyl (CF3SO2) THF ..........................................................tetrahydrofuran THP ..........................................................tetrahydropyran TLC ..........................................................thin layer chromatography TMS .........................................................trimethylsilyl 6 Contents 1.0 Introduction and Background ............................................................................................... 11 1.1 Isolation and Biological Activity ...................................................................................... 11 1.2 Retrosynthesis .................................................................................................................... 12 1.3 Biological significance of (S)-β-angelica lactone of natural products ............................... 13 1.3.1 Previous syntheses of (S)-β-angelica lactone of natural products in the literature ............................................................................................................................... 14 1.3.2 Previous work in the Collison Group on the butenolide moiety ................................ 16 1.4 Previous routes towards unsaturated sidechain 8 in the literature .................................... 19 1.4.1 Previous synthetic approaches to sidechain 8 in Collison Group (O. Augusto) ....... 19 1.4.2 Previous synthetic approaches to sidechain 8 in Collison Group (W. Spencer) ....... 21 2.0 Synthetic Design ................................................................................................................... 28 3.0 Results .................................................................................................................................... 30 3.1 Synthesis and optimization of butenolide 6 ...................................................................... 30 3.1.1 Synthesis of alkyne 14 from tosylate 16 .................................................................... 30 3.1.2 Cyclization and lactonization of alcohol 14 to afford butenolide 6 ........................... 30 3.2 Synthesis of acid chloride coupling partner .....................................................................