The marine natural product scabrolide A was obtained by isomerization of the vinylogous 1,4-diketone entity of nominal scabrolide B as the purported pivot point of the biosynthesis of these polycyclic norcembranoids. Despite the success of this maneuver, the latter compound itself turned out not to be identical with the natural product of that name. The key steps en route to the carbocyclic core of
海洋
天然产物 scabrolide A 是通过将标称 scabrolide B 的
乙烯基 1,4-二酮实体异构化作为这些多环去甲壳素
生物合成的所谓枢纽点而获得的。尽管这种策略取得了成功,但后一种化合物本身与该名称的
天然产物并不相同。通往这些目标的碳环核心的关键步骤是烯丙基
硫叶立德的 [2,3]-sigmatropic 重排以形成过度拥挤的 C12-C13 键,RCM 反应以闭合拥挤的中央六元环,以及羟基导向的环氧化/
环氧化物开环/异构化序列,以设置“umpoled”1,4-二羰基基序和 C12 处的正确角构型。