Stereoselective total synthesis of (±)-hyperforin via intramolecular cyclopropanation

Abstract

Total synthesis of (±)-hyperforin is described. This total synthesis features an approach via a bicyclo[3.3.1]nonane derivative prepared by a three-step sequence: intramolecular cyclopropanation, construction of the C8 all-carbon quaternary stereogenic center, and subsequent regioselective ring opening of cyclopropane. Further steps to obtain (±)-hyperforin include chemo- and stereoselective hydrogenation to generate the C7 stereogenic center, formation of the C9 isopropyl ketone using an organocerium reagent, and cross-metathesis at high temperatures to construct trisubstituted alkenes in side-chains.