Facile Access to Quaternary Carbon Centers via Ni-Catalyzed Arylation of Alkenes with Organoborons.

Quaternary carbon centers are widespread structural motifs, thus representing extensive interest in organic synthesis. We describe here an efficient nickel-catalyzed intermolecular, -selective arylation of minimally functionalized alkenes with stable organoborons, affording a broad range of cyclic or acyclic quaternary carbon centers under mild conditions. The utilization of the diimine ligand is critical for high reactivity and chemoselectivity. Furthermore, using a bulky chiral diimine as the ligand for the Ni catalyst, quaternary carbon stereocenters can be readily prepared with high levels of enantiocontrol. Mechanism studies suggest that, before protonation, a rare nickel shift from alkyl nickel to aryl nickel might occur.