Metallic salt promoted radical cyclization of β-keto carboxamides and their corresponding β-enamino carboxamides

Substituted lactams and spirolactams were obtained by Mn(III)-induced radical cyclization of unsaturated beta -keto carboxamides. Treatment of the corresponding tertiary enamines under similar reaction conditions and in the presence of K2CO3 afforded the same cyclized products but with inversion of diastereoselectivity. The oxidation of optically pure secondary enamines leads to diastereomeric spirolactams in an approximately 3:1 ratio.