Progress Toward the Total Synthesis of PM-toxin A And Future Development of Mild Lewis Acid Activated Alkynylation of Epoxides Open Access

Abstract

Progress Toward the Total Synthesis of PM-toxin A
And
Future Development of Mild Lewis Acid Activated Alkynylation of Epoxides
By Chandra Potter
The natural product, PM-toxin A ( 1), is a pathogen that causes leaf blight
and sterility to the male maize. In preparation for the synthesis of ( 1) we have
synthesized racemic model compound ( 2). The development of a synthetic
pathway for ( 2), described herein, demonstrates the viability of each technical
step in the asymmetric synthesis of PM-toxin A. A key step in the synthesis is
the nucleophilic opening of an epoxide via an acetylide ion to afford the
homopropargylic alcohol. Current methodology for the alkynylation of epoxides
uses n-butyllithium, for the deprotonation of the terminal alkyne, and boron
trifluoride-diethyl etherate or boron trifluoride-tetrahydrofuran, to activate the
epoxide, at low temperatures (e.g., -78 °C). Future work will include
development of mild reaction conditions for successful Lewis acid activated
alkynylation of epoxides using a tertiary amine for the deprotonation of the
terminal alkyne.

Progress Toward the Total Synthesis of PM-toxin A
And
Future Development of Mild Lewis Acid Activated Alkynylation of Epoxides
By
Chandra Potter
B.S., College of Charleston, 2009
Advisor: Frank E. McDonald, Ph.D.
A thesis submitted to the Faculty of the
James T. Laney School of Graduate Studies of Emory University
in partial fulfillment of the requirements for the degree of
Master of Science
in Chemistry
2011

Table of Contents

Table of Contents

Versatility of the Alkynylation of Epoxides
Introduction 1
Examples 4
Toward the Total Synthesis of PM-toxin A
Introduction and Background 10
Results and Discussion
Model System 13

Progress Toward the Total Synthesis of PM-toxin A 21
Conclusions and Future Directions
Completion of Total Synthesis of PM-toxin A 23
Development of Lewis Acid Activated Epoxide Alkynylation 24
Experimental Details 29
References 48

About this Master's Thesis

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School	Laney Graduate School
Department	Chemistry
Degree	MS
Submission	Master's Thesis
Language	English
Research Field	Chemistry, Organic
Keyword	organic alkynylation epoxide PM-toxin A synthesis
Committee Chair / Thesis Advisor	McDonald, Frank, Emory University
Committee Members	Liotta, Dennis C, Emory University Liebeskind, Lanny S, Emory University

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