[GRAPHICS]A concise approach to the eupomatilone family of lignans is presented, The strategy employs an intramolecularly competitive Ireland-Claisen rearrangement of a densely functionalized bis-allylic ester. The rearrangement serves both to construct the A-ring and to establish the stereochemistry at C-3 and C-4.
An Ireland−Claisen Approach to Lignans: Synthesis of the Putative Structure of 5-<i>epi</i>-Eupomatilone-6
作者:John M. Hutchison、Sang-phyo Hong、Matthias C. McIntosh
DOI:10.1021/jo049817r
日期:2004.6.1
A novel Ireland−Claisen approach to the putativestructure of eupomatilone-6 is described. The rearrangement established the C3 and C4 stereocenters and concomitantly generated a vinyl epoxide. The C5 oxygen was installed by cyclization of the pentenoic acid carboxyl group onto the vinyl epoxide in an SN2‘ fashion to afford the C5-epi stereochemistry. The natural C5 stereochemistry was accessed via
描述了一种新颖的爱尔兰-克莱森方法,该方法推定了eupomatilone-6的推定结构。重排建立了C3和C4立体中心,并随之生成了乙烯基环氧。通过将戊烯酸羧基以S N 2'方式环化到乙烯基环氧化物上来安装C5氧,以提供C5-epi立体化学。天然的C5立体化学是通过底物定向的二羟基化而获得的。