Copper catalyzed/mediated direct B-H alkenylation/alkynylation in carboranes

Base metal catalyzed regioselective cage B-H functionalization has been achieved. Under the assistance of a bidentate directing group, Cu-catalyzed [4+2] annulation of carboranyl amides with internal alkynes affords unprecedented C,B-substituted carborane-fused-pyridone derivatives, whereas the use of terminal alkynes leads to B-H/C(sp)-H dehydrocoupling products. The isolation and structural identification of a notably stable Cu(I) intermediate shed light on the reaction mechanism, which is proposed to involve a Cu(III) intermediate.