An Enantioselective Total Synthesis of (+)- and (-)-Saudin. Determination of the Absolute Configuration

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• 作者：Robert K. Boeckman ; Jr. ; Maria del Rosario Rico Ferreira ; Lorna H. Mitchell ; and Pengcheng Shao
• 刊名：Journal of the American Chemical Society
• 出版年：2002
• 出版时间：January 16, 2002
• 年：2002
• 卷：124
• 期：2
• 页码：190 - 191
• 全文大小：49K
• 年卷期：v.124,no.2(January 16, 2002)
• ISSN：1520-5126

文摘

A short efficient enantioselective synthesis of both (+)- and (-)-saudin, a naturally occurring hypoglycemic diterpene, is described. This synthesis establishes the absolute configuration of natural (-)-saudin for the first time. The key steps include the enantioselective construction of a dimethyl Hagemann's ester by an asymmetric Michael reaction and establishment of the key 1,3 disposed quaternary centers by means of a novel Ti(IV) promoted Claisen rearrangement. The assembly of the polycyclic ketal skeleton was likely under kinetic control proceeding via formation of the C₁oxygen-C₇ bond through an oxonium ion intermediate in the final stage.