Computational Insights into the Reactivity Difference between Hypervalent Bromine(III) and Hypervalent Iodine(III) Reagent in the C-H Amination and Alkene Aziridination

We present herein a computational exploration into the mechanism and origin of the reactivity difference between N-triflylimino-lambda(3)-iodane and N-triflylimino-lambda(3)-bromane in the C-H amination and alkene aziridination. Our calculations revealed that the preferred mechanism for C-H amination involves the generation of free nitrene intermediate, while the alkene aziridination proceeds via a concerted reaction mechanism. The superior reactivity of N-triflylimino-lambda(3)-bromane over N-triflylimino-lambda(3)-iodane could be mainly ascribed to better nucleofugality of the bromanyl moiety, which can be characterized by the strength of I-N and Br-N bond. The effect of solvent polarity on the reactivity of N-triflylimino-lambda(3)-bromane as a nitrene precursor will be discussed.