Total Synthesis of Norcembrenolide B and Scabrolide D

An efficient stereoselective synthesis of norcembrenolide B (8) and scabrolide D (9) is reported. The strategy is inspired by biogenetic relationships of related cembrenoids. Central to this approach is the construction of norbipinnatin J which upon selective C2 deoxygenation and C8 oxygenation produces norrubifolide and norcoralloidolide A. A sequence of site-selective oxidations and skeletal reorganizations then yields, in a divergent manner, compounds 8 and 9. The studies allow revision of the proposed structure of scabrolide D (9), which is identical to norcembrenolide C.

本研究报道了诺西布烯内酯B（norcembrenolide B，8）与糙皮内酯D（scabrolide D，9）的高效立体选择性全合成。该合成策略的设计灵感来源于相关西松烷型二萜（cembrenoids）的生源关系。本策略的核心在于诺双松针素J（norbipinnatin J）的构建，该中间体经选择性C2位脱氧与C8位氧化反应，可生成诺鲁比叶内酯（norrubifolide）与诺珊瑚内酯A（norcoralloidolide A）。随后通过一系列位点选择性氧化与骨架重排反应，以发散式合成路径分别得到化合物8与9。本研究修正了糙皮内酯D（scabrolide D，9）的推定结构，该化合物实际与诺西布烯内酯C（norcembrenolide C）完全一致。