Amination of carboranes has a good application prospect in organic and pharmaceutical synthesis. However, the current methods used for this transformation suffer from limitations. Herein, we report a practical method for a highly regioselective formation of a B−N bond by Pd(II)-catalyzed B( 9)-H amination of oand m-carboranes in hexafluoroisopropanol (HFIP) with different nitrogen sources under air atmosphere. The silver salt and HFIP solvent play critical roles in the present protocol. The mechanistic study reveals that the silver salt acts as a Lewis acid to promote the electrophilic palladation step by forming a heterobimetallic active catalyst PdAg(OAc) 3 ; the strong hydrogen-bond-donating ability and low nucleophilicity of HFIP enhance the electrophilic ability of Pd(II). It is believed that these N-containing carboranes are potentially of great importance in the synthesis of new pharmaceuticals.

Herein, we present a chemically robust and efficient synthesis route for B(9)-OH-o-carboranes by the oxidation of ocarboranes with commercially available 68% HNO 3 under the assistance of trifluoromethanesulfonic acid (HOTf) and hexafluoroisopropanol (HFIP). The reaction is highly efficient with a wide scope of carboranes, and the selectivity of B(9)/B(8) is up to 98:2. The success of this transformation relies on the strong electrophilicity and oxidizability of HNO 3 , promoted through hydrogen bonds of the Brønsted acid HOTf and the solvent HFIP. Mechanism studies reveal that the oxidation of o-carborane involves an initial electrophilic attack of HNO 3 to the hydrogen atom at the most electronegative B(9) of o-carborane. In this transformation, the hydrogen atom of the B−H bond is the nucleophilic site, which is different from the electrophilic substitution reaction, where the boron atom is the nucleophilic site. Therefore, this is an oxidation−reduction reaction of o-carborane under mild conditions in which N(V) → N(III) and H(-I) → H(I). The derivatization of 9-OH-o-carborane was further examined, and the carboranyl group was successfully introduced to an amino acid, polyethylene glycol, biotin, deoxyuridine, and saccharide. Undoubtedly, this approach provides a selective way for the rapid incorporation of carborane moieties into small molecules for application in boron neutron capture therapy, which requires the targeted delivery of boron-rich groups.