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

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 ArN 3 (Ar = 2,6-iPr 2 C 6 H 4 , 2,6-C 6 H 3 Cl 2 , 2,4,6-C 6 H 2 Br 3 , C 6 F 5 ) resulted in the cycloaddition of ArN 3 to the borirane BN unit accompanied by silyl migration. Conversely, in the reaction with BnN 3 , only the BnN 3  : borirane 1 : 2 ring expansion product was obtained. Finally, the reaction with Me 3 SiN 3 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.