Amide C-N bond formation-induced 1,2-aryl migration of alkyl aryl ketones in the cascade reaction with primary amines towards α,α-diaryl β, γ-unsaturated γ-lactams.

Abstract

The rearrangement reactions incorporated in cascade reactions play an important role in rapidly increasing molecular complexity from the readily available starting materials. We herein report a Cu-catalyzed cascade reaction of α- (hetero)aryl-substituted alkyl (hetero)aryl ketones with primary amines that incorporates an unusual amide C-N bond formation-induced 1,2-aryl migration of alkyl aryl ketone to produce a class of structurally novel α,α-diaryl β,γ-unsaturated γ-lactams in generally good -to-excellent yields. This cascade reaction enjoys a broad substrate scope with respect to primary amines, allows a wide spectrum of (hetero)aryl groups to smoothly undergo 1,2-migration regardless of their identities, and tolerates electronically diverse (hetero)aryl α-substituents of ketones though these (hetero)aryl α-substituents are essential to the reaction. Mechanistically, this 1,2-aryl migration may stem from the intramolecular amide C-N bond formation which induces nucleophilic migration of aryl group from acyl carbon to the electrophilic carbon that is conjugated with the resulting iminium moiety.