Iridium-Catalyzed Selective B(4)-H Acylmethylation of o -Carboranes with Sulfoxonium Ylides.

A highly efficient Ir-catalyzed regioselective cage B(4)-H acylmethylation of o -carboranyl acids using sulfoxonium ylides as alkylating regents has been developed, leading to the preparation of a large class of B(4)-acylmethylated o -carboranes in good to excellent yields with a broad substrate scope under redox neutral conditions. The -COOH moiety serves as the traceless directing group and controls the regioselectivity and monoselectivity.