Catalytic Regioselective Cage B(8)–H Arylation of <i>o</i>‑Carboranes via “Cage-Walking” Strategy

A proof-of-concept example of catalytic regioselective cage B(8)–H functionalization of o-carboranes has been disclosed for the first time. Under the help of an acylamino directing group at cage B(3), a series of B(8)-arylated, B­(4,7,8)-triarylated and B­(4,7,8)-trifluorinated o-carborane derivatives were conveniently prepared. On the basis of isolation of a key intermediate, deuterium labeling experiments and DFT calculations, a reaction mechanism involving a high-valent palladium induced “cage-walking” from B(4) to B(8) vertex is proposed to account for the regioselective B(8)–H activation.