N-Heterocyclic Carbene Catalyzed Asymmetric Hydration: Direct Synthesis of α-Protio and α-Deuterio α-Chloro and α-Fluoro Carboxylic Acids

Asymmetric hydration of α,α-dichloro aldehydes and α-halo enals via a NHC-catalyzed redox process to yield enantioenriched α-chloro and α-fluoro carboxylic acids is described herein. The developed reaction allows for installation of an α-deuterium to give rise to enantioenriched α-deutero α-halo acids using D2O as the deuteron source.