Palladium-Catalyzed Regioselective Diarylation of o-Carboranes By Direct Cage B-H Activation

Palladium-catalyzed intermolecular coupling of o-carborane with aromatics by direct cage B-H bond activation has been achieved, leading to the synthesis of a series of cage B(4,5)-diarylated-o-carboranes in high yields with excellent regioselectivity. Traceless directing group -COOH plays a crucial role for site-and di-selectivity of such intermolecular coupling reaction. A Pd-II-Pd-IV-Pd-II catalytic cycle is proposed to be responsible for the stepwise arylation.