Palladium-catalyzed B7–11 penta-arylation of the {CB₁₁} monocarborane cluster

Regioselective, five-fold B-H activation of the monocarborane cluster [CB11H12]- at the positions B7-11 has been accomplished. Selective substitution of these positions by B-H activation has not been reported before. Our protocol involves directing group assistance by the carboxylic acid functionality and is based on palladium catalysis using iodoarene coupling partners. Penta-arylated products are obtained in a single step with yields ranging from 42% to 89% and with good functional group tolerance. X-Ray crystal structures for five new compounds confirm the selective substitution of the lower belt of the monocarborane cage.