Enantioselective Synthesis of Vicinal Halohydrins via Dynamic Kinetic Resolution

Expanding the scope of enantioselective catalysis via DKR, transfer hydrogenation of a variety of cyclic α-halo ketones was accomplished using the Noyori/Ikariya (R,R)- or (S,S)-I catalysts and either HCO₂H/Et₃N or HCO₂Na/n-Bu₄NBr in H₂O/CH₂Cl₂ as the hydrogen sources. Good yields of vicinal bromo-, chloro-, and fluorohydrins with excellent de and ee levels were achieved in most cases after a simple tuning of reaction conditions.