Highly Regioselective Functionalization of Triborane (L·B ₃ H ₇ ) through Copper-Catalyzed B–H Bond Insertion Reaction of Tosylhydrazone Compounds

A highly regioselective copper-catalyzed B-H bond insertion of triboranes with tosylhydrazones provides diverse organoboron compounds. This method exhibits a broad substrate scope and excellent functional-group compatibility under mild conditions. The reaction is highly selective for the B(2) position, and the resulting B(2)-substituted products can undergo further insertion to yield B(2,3)-disubstituted triboranes. Furthermore, this strategy offers a practical pathway for synthesizing ¹⁰B-labeled agents for boron neutron capture therapy (BNCT).