Iridium(III)-Catalyzed B(4)-Acylmethylation and B(3,5)‑Diacylmethylation from o‑Carboranes and Sulfoxonium Ylides

An iridium­(III)-catalyzed regioselective acylmethylation of the cage B(4)–H bond in o-carborane acids with sulfoxonium ylides is demonstrated through B(4)–H activation in ethanol under very mild conditions, affording a number of B(4)-acylmethylated o-carboranes. Additionally, the selective sequential B(4)- and B(6)-acylmethylation reactions finally gave B­(3,5)-diacylmethylated o-carboranes in one pot.