Cross-Metathesis Approach to the Tricyclic Marine Alkaloids (-)-Fasicularin and (-)-Lepadiformine A.

A cross-metathesis protocol has been developed to provide facile access to highly hindered trisubstituted α-branched olefins, which when coupled with a cationic azaspirocyclization reaction, generates the marine alkaloids (-)-fasicularin 2 and a pro-forma synthesis of (-)-lepadiformine A 1.