Effect of a ligand on the asymmetric hydrogenation of cyclic N-sulfonyl amines catalyzed by nickel.

The present study utilizes density functional theory (DFT) to systematically investigate the effect of a ligand on the mechanism of nickel-catalyzed asymmetric hydrogenation of cyclic N-sulfonyl imines, employing alcohol protons as the hydrogen source. By comparing the free energies of three catalytic pathways involving various coordinated nickel complexes with different ligands, we identify that the enantio-determining step is the nickel-hydride transfer. Notably, the reaction pathway initiated by the Ni(0) species through oxidative addition of alcohol is determined to be the most favorable. Distortion-interaction analysis reveals that distortion and steric repulsions significantly influence the major pathway. Furthermore, enantioselectivity calculations demonstrate that the preferential formation of the major S-configured product is attributed to interaction energies through electrostatic interaction and CH-π interaction. This study elucidates the mechanism underlying nickel(0)-catalyzed asymmetric hydrogenation.