Total Synthesis of (-)-Stemoamide Using Ruthenium-catalyzed Enyne Metathesis Reaction

A total synthesis of (-)-stemoamide was achieved from (-)-pyroglutamic acid using a ruthenium-catalyzed enyne metathesis as a key step, in 14 steps in 9% overall yield.Stemoamide, which was first isolated from the roots and rhizomes of Srernonaceous plants, is a polycyclic alkaloid similar to stemonine, stenine and stemospironine, and possesses powerful insecticidal activity.'.'The first total synthesis of stemoamide was achieved by Williams.'Intramolecular enyne metathesis4 is a very attractive and unique tool for synthetic organic chemistry.We previously reported the enyne metathesis5 using a ruthenium catalyst developed by G ~b b s .~