80 4環性ギンコライドの合成(口頭発表の部)

概要

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We have recently described a total synthesis of ginkgolide B(1), a potent antagonist of platelet activating factor, and also the application of this chemical route to the synthesis of structurally simpler analogs of 1. Since certain of these synthetic analogs lacking ring F and the groups attached to C(3) showed biological activity comparable to 1 itself, the synthesis and study of the even simpler tetracyclic fourteen-carbon analog(2) of ginkgolide B lacking ring A and F became of great interest. We have synthesized 2 from aldehyde 7 in a short and efficient way. This synthesis of tetracyclic dilactone 2 features a number of noteworthy steps and methods including the following: (1) the successful stereospecific construction of the spiro-fused ring system of 13 using a tactical combination of cis-Wittig olefination, carbenoid ring closure and lactonization; (2) stereospecific conjugate addition to introduce the t-butyl appendage; and (3) a novel annulation to attach the final lactone ring.
天然有機化合物討論会の論文
1990-09-25