Diastereoselective Total Synthesis of (±)-Basiliolide B and (±)-<i>epi</i>-8-Basiliolide B

The C8 and C9 stereogenic centers of the basiliolide/transtaganolide family have been established stereoselectively using a cyclopropane ring-opening strategy, which has been studied by DFT calculations of a variety of lithium-chelating models. The highly functionalized intermediates obtained in this strategy were successfully employed for the diastereoselective total synthesis of (±)-basiliolide B and (±)-epi-8-basiliolide B. The decalin core with a lactone bridge was constructed via a 2-pyrone Diels–Alder (DA) cycloaddition, and the unprecedented seven-membered acyl ketene acetal was established by a biomimetic intramolecular O-acylation cyclization.巴西林内酯 (basiliolide)/川参内酯 (transtaganolide) 家族的C8及C9手性中心，可通过环丙烷开环策略实现立体选择性构建；该策略已通过多种锂螯合模型的密度泛函理论 (Density Functional Theory，DFT) 计算开展了系统研究。通过该策略得到的高官能团化中间体，已成功应用于外消旋(±)-巴西林内酯B与外消旋(±)-8-差向巴西林内酯B的非对映选择性全合成。带有内酯桥的十氢化萘母核，经由2-吡喃酮狄尔斯-阿尔德 (Diels–Alder，DA) 环加成反应构建；前所未有的七元酰基烯酮缩醛结构，则通过仿生分子内O-酰基化环化反应得以确立。