文摘
We examine important reactivity pathways relevant to stoichiometric and catalytic C鈥揌 amination via isolable 尾-diketiminato dicopper alkylnitrene intermediates {[Cl2NN]Cu}2(渭-NR). Kinetic studies involving the stoichiometric amination of ethylbenzene by {[Cl2NN]Cu}2(渭-NtBu) (3) demonstrate that the terminal nitrene [Cl2NN]Cu鈺怤tBu is the active intermediate in C鈥揌 amination. Initial rates exhibit saturation behavior at high ethylbenzene loadings and an inverse dependence on the copper species [Cl2NN]Cu, both consistent with dissociation of a [Cl2NN]Cu fragment from 3 prior to C鈥揌 amination. C鈥揌 amination experiments employing 1,4-dimethylcyclohexane and benzylic radical clock substrate support a stepwise H-atom abstraction/radical rebound pathway. Dicopper nitrenes [Cu]2(渭-NCHRR鈥? derived from 1掳 and 2掳 alkylazides are unstable toward tautomerization to copper(I) imine complexes [Cu](HN鈺怌RR鈥?, rendering 1掳 and 2掳 alkylnitrene complexes unsuitable for C鈥揌 amination.