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.