The Importance of Iminium Geometry Control in Enamine Catalysis: Identification of a New Catalyst Architecture for Aldehyde–Aldehyde Couplings

Central to the design of a new organocatalyst system for aldehyde–aldehyde aldol reactions is the necessity of iminium geometry control during the enamine addition step (see scheme). Significant structural variation in both the aldol donor and aldol acceptor are possible while maintaining high reaction efficiency and enantioselectivity. TFA=trifluoroacetic acid.