Three-component synthesis of tricyclic lactams containing the pyrrolizidin-3-one moiety

Abstract

Tricyclic lactams containing the pyrrolizidin-3-one moiety were synthesized by the three-component reaction of aromatic aldehydes, glutamic acid (or glutamine), and N-methylmaleimide. The cascade reactions involve the stereospecific generation of azomethine ylides, the 1,3-dipolar endo- and exo-cycloaddition of a dipolarophile to the ylides, and the lactamization and afford two series of stereoisomeric pyrrolizidin-3-ones. The alkaline hydrolysis of the products of the mulitcomponent reaction gives oxopyrrolizidinedicarboxylic acid derivatives.