Organocatalytic Enantioselective Functionalization of Cyclic α-Hydroxyamides: Access to Chiral Cyclic Imides and Azapolycyclic Compounds.

A highly efficient enantioselective enamine-catalyzed asymmetric conjugate addition has been developed to directly convert unfunctionalized cyclic α-hydroxyamides into chiral cyclic α-hydroxyamides by reacting with vinyl sulfones, which could be used as versatile azacyclic synthons in the following sequences: (1) as the precursors of cyclic N -acyliminium ions to prepare natural productlike chiral azapolycyclic compounds under acidic conditions and (2) to construct chiral cyclic imides bearing unilateral substituents via oxidation reaction-induced formal desymmetrization.