Rhodium-Catalyzed Asymmetric Addition of Potassium Organotrifluoroborates to N-Sulfonyl Ketimines

A rhodium-catalyzed asymmetric addition of readily available potassium organotrifluoroborates to both N-tosyl and N-nosyl ketimines has bean developed. High enantioselectivity has been achieved by using a chiral diene ligand, and the nosyl group of the addition products can be easily removed while retaining the enantiomeric purity.