Iridium(III)-Catalyzed Selective Sulfonamidation of o-Carborane with Sulfonyl Azide by Carboxylic Acid-Assisted B(4)-H Bond Activation

An iridium-catalyzed cage B-H sulfonamidation of o-carborane directed by a carboxylic acid group is reported that proceeds in the absence of ligands or external oxidants. A series of sulfonyl azides can be selectively sulfonamidated at the B(4) site in high yields with excellent functional group tolerance. This approach can also be applied to aryl and aliphatic azides. Innocuous CO2 and N-2 were released as byproducts. In addition, the carboxylic acid group can be easily removed under mild conditions.