Core Structure of Eremophilanes and Bakkanes through Niobium Catalyzed Diels−Alder Reaction: Synthesis of (±)-Bakkenolide A

A suitable intermediate for the synthesis of eremophilanes and bakkanes was prepared by a highly regioselective and stereoselective one-step synthesis through a niobium catalyzed Diels−Alder reaction. As a demonstration of the versatility of this intermediate, a total synthesis of (±)-bakkenolide A is described.