Palladium‐Catalyzed Carbonylative Annulation of 1‐Hydroxy‐o‐Carborane and Internal Alkynes via Regioselective B‐H Activation

A Pd-catalyzed three-component carbonylative-annulation of 1-hydroxy- o -carborane, internal alkyne and carbon monoxide has been achieved via direct and regioselective cage B-H activation. A class of C,B-substituted carborano-coumarin derivatives with potential applications in pharmaceuticals were facilely prepared in moderate to high yields with excellent chemoselectivity and regioselectivity. A plausible reaction mechanism including CO insertion, electrophilic B-H metalation, alkyne insertion and reductive elimination was proposed.