Formal Homoiodo Allylsilane Annulations: Dual Total Syntheses of (±)-Hirsutene and (±)-Capnellene

Dual total syntheses of (±)-hirsutene and (±)-capnellene, two typical linear triquinane sesquiterpenes, were achieved via a formal [3 + 2] annulation strategy, as illustrated schematically. Cyclic homoiodo allylsilanes were employed as key bifunctional synthons in the synthesis, which were readily prepared from the corresponding cyclopropanated cyclopentenones. A formal [3 + 3] annulation approach for the elaboration of the bicyclic framework of the Eudesmane sesquiterpenoids based on this type of synthon was also developed.

本研究成功实现了两种典型直链三奎烷型倍半萜（sesquiterpenes）——(±)-海斯特烯（hirsutene）与(±)-帽贝烯（capnellene）——的外消旋体全合成，该合成采用形式上的[3+2]环合策略，如示意图所示。合成过程中以环状高碘代烯丙基硅烷作为关键双官能团合成子（synthon），此类合成子可由对应的环丙烷化环戊烯酮便捷制备得到。此外，本研究还基于该类合成子，开发了一种用于构建桉叶烷型倍半萜类（sesquiterpenoids）化合物双环骨架的形式[3+3]环合策略。