Organocatalytic Heterocyclization Driven by Dynamic Kinetic Resolution: Enantioselective Access to Multi-heteroatomic Cyclic Structures Mediated by Cinchona Alkaloid-based Catalysts

A new class of multi-heteroatomic cyclic compounds containing N, S and O has been achieved in an enantioselective fashion via desymmetrization of 2-cyano-N-tosylbenzylidenimine with thiols and subsequent catalytic dynamic kinetic resolution (DKR). Both organo- and phase transfer catalysis based on cinchona alkaloids having two H-bonding coordination sites proved to be effective to furnish very good level of enantioselectivity (up to 95:5 er) in the heterocyclization of racemic N-Tosyl-protected N,S-acetals deriving from 2-formyl benzonitriles.