Density Functional Theory Study on Mechanism and Selectivity of Nickel-Catalyzed Hydroboration of Vinylarenes

Abstract

Density functional theory calculations were performed to elucidate the mechanistic details and origins of the selectivity of the nickel-catalyzed hydroboration of vinylarenes using B2 pin2 /MeOH. The catalytic cycles involved four sequential elementary steps: hydron-ickelation, anion exchange, transmetalation, and reductive elimination. Kinetic analyses identified hydronickelation as the rate-determining step with an activation barrier of 19.8 kcal/mol, while transmetalation proceeded through a stepwise mechanism characterized by two distinct transition states. Comprehensive analyses of the relevant transition structures and energetics demonstrated that the observed R-enantioselectivity (94% ee) originated from favorable nonbonding interactions. Lastly, our calculations suggested that the Markovnikov regioselectivity was predominantly governed by steric factors rather than electronic effects.