Mechanistic Insights into C鈥揌 Amination via Dicopper Nitrenes

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• 作者：Mae Joanne B. Aguila ; Yosra M. Badiei ; Timothy H. Warren
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：June 26, 2013
• 年：2013
• 卷：135
• 期：25
• 页码：9399-9406
• 全文大小：466K
• 年卷期：v.135,no.25(June 26, 2013)
• ISSN：1520-5126

文摘

We examine important reactivity pathways relevant to stoichiometric and catalytic C鈥揌 amination via isolable 尾-diketiminato dicopper alkylnitrene intermediates {[Clb>2b>NN]Cu}b>2b>(渭-NR). Kinetic studies involving the stoichiometric amination of ethylbenzene by {[Clb>2b>NN]Cu}b>2b>(渭-N^tBu) (<b>3b>) demonstrate that the terminal nitrene [Clb>2b>NN]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 [Clb>2b>NN]Cu, both consistent with dissociation of a [Clb>2b>NN]Cu fragment from <b>3b> 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]b>2b>(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.