Enantioselective Synthesis of Benzylic Boronic Esters via Photoredox/Nickel-Catalyzed Multicomponent Cross-Couplings.

Abstract

As a class of versatile building blocks, chiral benzylic boronic esters are important intermediates employed in modern organic chemistry. We describe herein the first stereoconvergent multicomponent cross-coupling reaction of vinyl boronates, alkyltrifluoroborates, and aryl halides through a dual photoredox/nickel catalysis methodology. This synergistic platform permitted the benign construction of various enantioenriched benzylic boronic esters with broad substrate tolerance and moderate to excellent enantioselectivity (up to 98:2 er) from commercially available starting materials. Moreover, experimental and computational studies shed light on the nickel catalytic transformation and the origin of the enantioselectivity.