Controlled functionalization of o-carborane via transition metal catalyzed B–H activation

Carboranes, a class of carbon–boron molecular clusters, are often viewed as three-dimensional analogues of benzene. They are finding increasing applications as useful functional building blocks in materials science, medicine, organometallic/coordination chemistry and more. Thus, functionalization of carboranes has received considerable attention. In comparison with the weakly acidic cage C–H bonds that can be readily functionalized, selective cage B–H functionalization among ten chemically similar BH vertices in o-carboranes is very challenging. Only in the recent few years, considerable progress has been made in transition metal catalyzed vertex-specific BH functionalization. This review summarizes recent advances in this research area.