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

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.