Total synthesis of (±)-stemonamide and (±)-isostemonamide

Two different approaches to the alkaloids stemonamide and isostemonamide using N-acyliminium chemistry are described. The approach using an aldol spirocyclization to construct the second contiguous spirocenter was successful. The total synthesis of these products was completed by 1,4-addition of an appropriate side chain, α-methylenation by Mannich reaction, double bond isomerization and closure of the azepine ring.