Avenue to novel o-carboranyl boron compounds – reactivity study of o-carborane-fused aminoborirane towards organic azides

Abstract

Herein we report the reactivity study of o-carborane-fused bis(trimethylsilyl)aminoborirane towards three different types of organic azides, i.e., aryl, alkyl, and silyl azides. The reaction with ArN₃ (Ar = 2,6-iPr₂C₆H₄, 2,6-C₆H₃Cl₂, 2,4,6-C₆H₂Br₃, C₆F₅) resulted in the cycloaddition of ArN₃ to the borirane BN unit accompanied by silyl migration. Conversely, in the reaction with BnN₃, only the BnN₃ : borirane 1 : 2 ring expansion product was obtained. Finally, the reaction with Me₃SiN₃ resulted in a formal nitrene insertion product under thermal conditions. All of the newly obtained o-carborane-fused BN-containing heterocycles were fully characterized, and the mechanism of these substituent-dependent reactions was studied using DFT calculations.