Divergent Total Syntheses of <i>Illicium</i> Sesquiterpenes through Late-Stage Skeletal Reorganization
Pengfei Fu, Tao Liu, Yang Shen, Lei Xin, Tianjie Xiao, Peng Chen, Dongsheng Qiu, Zhen Wang, Yandong Zhang
Abstract
We disclose unified, protecting-group-free, bioinspired divergent total syntheses of eight allo -cedrane and seco -prezizaane Illicium sesquiterpenes and formal syntheses of five anislactone sesquiterpenes. The efficiency of our approach derives from rapid access to the 15-carbon tricyclic carboxylic acid through cationic epoxide-ene cyclization and HAT oxygenation, transformation of this intermediate into three distinct tricyclic precursors via Lewis acid-mediated skeletal reorganizations, subsequent programmed oxidation level enhancement, and a biomimetic oxidation-initiated skeletal rearrangement cascade. Consequently, we created a synthetic correlation map of the three most prevalent Illicium sesquiterpene families.