Catalytic Enantioselective Approach to the Eudesmane Sesquiterpenoids: Total Synthesis of (+)-Carissone

A catalytic enantioselective approach to the eudesmane sesquiterpenoids is reported. The strategic use of a palladium-catalyzed enantioselective alkylation of vinylogous ester substrates forged the C(10) all-carbon quaternary center. This key transformation enabled a diastereoselective olefin hydrogenation to create the syn stereochemistry at C(7). The devised synthetic strategy allowed for the preparation of the antibacterial agent (+)-carissone and a formal synthesis of the P/Q-type calcium channel blocker (-)-alpha-eudesmol.