72(P-63) 中員環ジテルペン化合物フォマクチン類の骨格合成機構(ポスター発表の部)

概要

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Phomactins are structurally unique diterpenes isolated from a marine fungus, Phoma sp., and are known as platelet-activating factor (PAF) antagonists. We started a biosynthetic study of phomacta-1(14),3,7-triene (1) which has the same carbon framework as that of phomactins and is regarded as a biosynthetic precursor. Compound 1 could be biosynthesized from geranylgeranyl diphosphate via verticillen-12-yl cation 2 which was proposed as an intermediate of taxadiene (Scheme 1). Based on the relative configuration of 1 and results of incorporation experiments (Figure 1, 2 and 3), the GGDP cyclization mechanism was proposed (Scheme 2). Two-step cyclizations of GGDP can occur via boat-like transition state and give the 12-yl cation 2. Sequential rearrangements including 1,2-shifts of 11-H, 15β-H, and 1β-H followed by deprotonation of 14-H provide 1.
天然有機化合物討論会の論文
2004-10-01