Radical Mediated Aza-Pauson-Khand Reaction of Acetylenes, Imines, and CO Leading to Five-Membered Unsaturated Lactams

Abstract

Formal [2+2+1] cycloaddition reaction involving acetylenes, aromatic imines, and CO was achieved by radical chain reaction, which gave five-membered unsaturated lactams in modest to good yields. When we used 5-chloropentyne, sequential carbonylation took place accompanied with double annulation events to give a cyclohexanone-fused lactam in excellent stereoselectivity.