Substituted lactams and spirolactams were obtained by Mn(III)-induced radical cyclization ofunsaturated β-keto carboxamides. Treatment of the corresponding tertiary enamines under similarreaction conditions and in the presence of K2CO3 afforded the same cyclized products but withinversion of diastereoselectivity. The oxidation of optically pure secondary enamines leads todiastereomeric spirolactams in an approximately 3:1 ratio.