Studies toward the total synthesis of altromycin natural products 公开

Abstract

Part 1. Synthesis of the Branched C-Glycoside Substructure of Altromycin B.

Tungsten-catalyzed cycloisomerization of alkynyl alcohol provides only the endocyclic enol ether as a key intermediate for the branched C-glycoside substructure of altromycin B. A sequence of Stille cross-coupling reaction and regio- and stereoselective functional group transformations affords each C13-diastereomer of the branched C-arylglycoside.

Part 2. Fischer Carbene Catalysis of the Alkynol Cycloisomerization: Application to the Synthesis of the Altromycin B Disaccharide.

The tungsten-catalyzed cycloisomerization of alkynols can be conducted without using photochemistry, using a stable tungsten Fischer carbene as the precatalyst for this transformation. A variety of alkynyl alcohols undergo cycloisomerization under these conditions to provide endocyclic enol ethers of 5, 6, and 7-membered ring sizes. The utility of this method is further demonstrated in the stereoselective synthesis of the disaccharide substructure of altromycin B.

Table of Contents

Part 1. Synthesis of Branched C-Glycoside Substructure of Altromycin B. 1. 1. Introduction and Background 1. 2. Results and discussion 1. 2. 1. Experiments for the formation of C-glycoside linkage (Hallberg's multiple Heck reaction). 1. 2. 2. Experiments for the formation of C-glycoside linkage (Yoshida's multiple Heck reaction). 1. 2. 3. Experiments for the formation of C-glycoside linkage(Stille cross coupling reaction). 1. 2. 4. Synthesis of branced C-glycoside substructure of altromycin B. 1. 3. Conclusions 1. 4. Experimental Section 1. 5. References Part 2. Fischer Carbene Catalysis of the Alkynol Cycloisomerization: Application to the Synthesis of the Altromycin B Disaccharide. 2. 1. Introduction and Background 2. 2. Results and discussion 2. 2. 1. Design and hypothesis of Fischer carbene catalysis. 2. 2. 2. Optimization of reaction conditions. 2. 2. 3. Comparison of non-photochemical and photochemical procedures. 2. 2. 4. Proposed mechanism for the Fischer carbene catalysis. 2. 2. 5. Synthesis of the east disaccharide substructure of altromycin B. 2. 3. Conclusions 2. 4. Experimental Section 2. 5. References

About this Dissertation

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School	Laney Graduate School
Department	Chemistry
Degree	PhD
Submission	Dissertation
Language	English
Research Field	Chemistry, Organic
关键词	total synthesis tungsten altromycins natural product
Committee Chair / Thesis Advisor	McDonald, Frank, Emory University
Committee Members	Padwa, Albert, Emory University Liebeskind, Lanny S, Emory University

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