Iridium Catalyzed Regioselective Cage Boron Alkenylation of <i>o-</i>Carboranes via Direct Cage B–H Activation

Iridium catalyzed alkyne hydroboration with <i>o-</i>carborane cage B–H has been achieved, leading to the formation of a series of 4-B-alkenylated-<i>o</i>-carborane derivatives in high yields with excellent regioselectivity via direct B–H bond activation. In this reaction the carboxy group is used as a traceless directing group, which is removed during a one-pot process. After the confirmation of a key intermediate, a possible mechanism is proposed, involving a tandem sequence of Ir-mediated B–H activation, alkyne insertion, protonation, and decarboxylation