Enantioselective total synthesis of atisane diterpenoids: (+)-sapinsigin H, (+)-agallochaol C, and (+)-16α, 17-dihydroxy-atisan-3-one

Abstract

Enantioselective total synthesis of (+)-sapinsigin H, (+)-agallochaol C, and (+)-16α, 17-dihydroxy-atisan-3-one has been accomplished starting from enantiopure Wieland–Miescher ketone. Key features of the syntheses include a benzannulation step to construct the tricyclic core, an oxidative dearomatization step to generate the diene, and a Diels–Alder reaction with ethylene gas to establish the bicyclo[2.2.2]octane framework. Efficient late-stage functionalisation of the A-ring by aerobic oxidation and Baeyer−Villiger oxidation completed the atisane target molecules.