Nickel-Catalyzed Asymmetric Transfer Hydrogenation and α-Selective Deuteration of N-Sulfonyl Imines with Alcohols: Access to α-Deuterated Chiral Amines.

A nickel-catalyzed enantioselective transfer hydrogenation and deuteration of N-sulfonyl imines was developed. Excellent α-selectivity and high deuterium content were achieved by using inexpensive 2-propanol-d8 as a deuterium source. As a highlight, no deuteration of β-C-H and the remote C-H of N-sulfonyl amines occurred, which is hard to achieve using other imines or by hydrogen isotope exchange with D2O. Mechanism studies indicated a stepwise pathway through the [Ni-D] intermediate.