Cycloaddition Reactions of Imines with 3-Thiosuccinic Anhydrides: Synthesis of the Tricyclic Core of Martinellic Acid

Abstract

Arylthio-substituted succinic anhydrides undergo cycloaddition reactions with imines to produce gamma-lactams in high yield and with high diastereoselectivity. The origin of the selectivity is proposed to result from anion-pi repulsion in the transition state. The utility of this technique is demonstrated in a synthesis of the carbon framework common to the alkaloids martinellic acid and martinelline in five steps.