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A palladium catalyzed selective B(3)–H activation/oxidative dehydrogenative coupling for the synthesis of bis­(o-carborane)­s connected with B(3)–B(3′) and B(3)–B(6′) bonds has been developed for the first time. A plausible mechanism involving stepwise activation of B(3)–H and B­(3′/6′)–H bonds by PdII and PdIV was proposed. This work is the first example and the most efficient protocol for synthesis of bis­(o-carborane)­s connected with B(3)–B(3′) and B(3)–B(6′) bonds, which has important reference for design, synthesis, and application of bis­(o-carborane)­s in related fields.

An in situ Pd-NHC catalyzed selective B­(3,6)-H activation for hydroboration of internal alkynes has been accomplished under mild conditions. This work offers a facile approach for the synthesis of alkenyl-o-carboranes and has important reference for selective functionalization of B­(3,6)–H bonds.

Aromatic heterocycles are ubiquitous building blocks in bioactive natural products, pharmaceutical and agrochemical industries. Accordingly, the carborane-fused heterocycles would be potential candidates in drug discovery, nanomaterials, metallacarboranes, as well as photoluminescent materials. In recent years, the transition metal catalyzed B-H activation has been proved to be an effective protocol for selective functionalization of B-H bond of o-carboranes, which has been further extended for the synthesis of polyhedral borane cluster-fused heterocycles via cascade B-H functionalization/annulation process. This article summarizes the recent progress in construction of polyhedral borane cluster-fused heterocycles via B-H activation.

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