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.