A designer axially chiral amino sulfonamide as an efficient organocatalyst for direct asymmetric mannich reactions of N-Boc-protected imines.

The moderate nucleophilicity of the axially chiral amino sulfonamide (S)-1 suppresses the problematic side reactions, including aldol reactions, in the asymmetric Mannich reaction of N-Boc-protected imines with aldehydes. The corresponding adducts are obtained in good yield and excellent stereoselectivity (see scheme; Boc = tert-butoxycarbonyl, Tf = trifluoromethanesulfonyl).