Nickel-Catalyzed Enantioselective Hydroboration of Vinylarenes.

The enantioselective hydroboration of vinylarenes catalyzed by a chiral, nonracemic nickel catalyst is presented as a facile method for generating chiral benzylic boronate esters. Various vinylarenes react with bis(pinacolato)diboron (B 2 pin 2 ) in the presence of MeOH as a hydride source to form chiral boronate esters in up to 92% yield with up to 94% ee. The use of anhydrous Me 4 NF to activate B 2 pin 2 is crucial for ensuring fast transmetalation to achieve high enantioselectivities.