Single-Electron Transmetalation: Synthesis of 1,1-Diaryl-2,2,2-trifluoroethanes by Photoredox/Nickel Dual Catalytic Cross-Coupling

摘要

Novel methods for the incorporation of fluorinated subunits into organic frameworks are important in pharmaceutical, agrochemical, and materials science applications. Herein, the first method for the cross-coupling of benzylic alpha-trifluoromethylated alkylboron reagents with (hetero) aryl bromides is achieved through application of a photoredoxickel dual catalytic system. The harsh conditions and high temperatures required by conventional Suzuki-coupling protocols are avoided by exploitation of an odd-electron pathway that permits room temperature transmetalation of these recalcitrant reagents. This method represents the first direct and general route for the synthesis of unsymmetrical 1,1-diaryl-2,2,2-trifluoroethanes, thereby providing efficient access to a previously unexplored chemical space.