Divergent Biomimetic Total Syntheses of Ganocins A–C, Ganocochlearins C and D, and Cochlearol T
Hui Shao, Xiaonan Gao, Zhong‐Tian Wang, Ziwei Gao, Yu‐Ming Zhao
Abstract
A divergent synthetic approach to six Ganoderma meroterpenoids, namely ganocins A-C, ganocochlearins C and D, and cochlearol T, has been developed for the first time. This synthetic route features a two-phase strategy which includes early-stage rapid construction of a common planar tricyclic intermediate followed by highly selective late-stage transformations into various Ganoderma meroterpenoids. Key to the strategy are a bioinspired intramolecular hetero-Diels-Alder reaction and Stahl-type oxidative aromatization, allowing efficient formation of the common tricyclic phenol intermediate. A nucleophilic dearomatization of the phenol unit, combined with a regioselective 1,4-reduction of the resulting dienone, enabled rapid access to ganocins B and C. Additionally, site-selective Mukaiyama hydration, followed by an intramolecular oxa-Michael addition/triflation cascade, served as a key strategic element in the chemical synthesis of ganocin A.