Bioinspired Synthesis of Nortriterpenoid Propindilactone G

A concise bioinspired
synthesis of Schisandra nortriterpenoid
propindilactone G has been accomplished from a readily accessible
steroidal lactone. Key transformations include a Breslow remote functionalization,
a Suárez remote radical functionalization, a ring expansion
enabled by a Wagner–Meerwein rearrangement, a stereoinversion
of a tertiary alcohol, and a biomimetic transesterification/oxa-Michael
addition cascade. This work also provides experimental evidence of
the putative propindilactone G biosynthesis pathway.

本研究以易得的甾体内酯为起始原料，完成了五味子降三萜类化合物丙二内酯G（propindilactone G）的简洁仿生全合成。关键合成步骤包括布雷斯洛远程官能化（Breslow remote functionalization）、苏亚雷斯远程自由基官能化（Suárez remote radical functionalization）、经由瓦格纳-迈尔外因重排（Wagner–Meerwein rearrangement）实现的环扩环反应、叔醇的立体构型翻转，以及仿生酯交换/氧杂迈克尔加成级联反应。本研究同时为推定的丙二内酯G生物合成途径提供了实验证据。