Enantioselective Parallel Kinetic Resolution of Aziridine-Containing Quinoxalines via Chiral Phosphoric Acid-Catalyzed Transfer Hydrogenation.

This article describes the asymmetric synthesis of chiral aziridinoquinoxalines using ( R )-TRIP-catalyzed parallel kinetic resolution under transfer hydrogenation conditions. This resolution was successfully accomplished for 16 different substrates and led to highly enantioenriched diastereomers with the ( R )-configuration of the newly formed stereocenter (32-61% yield and 64-99% ee for the ( R,R,R )-diastereomers and 7-46% yield and 97-99% ee for the ( S,S,R )-diastereomers). This process could be coupled to ring-opening of the ( S,S,R )-diastereomer with thiophenol to produce chiral tetrahydroquinoxalines with three contiguous stereocenters.