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The efficient transformation of nitroaromatics to functional molecules such as N-heterocycles has been an attractive and significant topic in synthesis chemistry. Herein, a photoexcited nitro-induced strategy for switchable annulation of...

The efficient and selective functionalization of icosahedral carboranes (C 2 B 10 H 12 ) at the boron vertexes is a long-standing challenge owing to the presence of 10 inert B−H bonds in a similar chemical environment. Herein, we report a new reaction paradigm for direct B−H functionalization of icosahedral carboranes via B−H homolysis enabled by a nitrogen-centered radical-mediated hydrogen atom transfer (HAT) strategy. Both the HAT process of the carborane B−H bond and the resulting boroncentered carboranyl radical intermediate have been confirmed experimentally. The reaction occurs at the most electron-rich boron vertex with the lowest B−H bond dissociation energy (BDE). Using this strategy, diverse carborane derivatization, including thiolation, selenation, alkynylation, alkenylation, cyanation, and halogenation, have been achieved in satisfactory yields under a photoinitiated condition in a metal-free and redox-neutral fashion. Moreover, the synthetic utility of the current protocol was also demonstrated by both the scale-up reaction and the construction of carborane-based functional molecules. Therefore, this methodology opens a radical pathway to carborane functionalization, which is distinct from the B−H heterolytic mechanism in the traditional strategies.