Mechanistic Insights into C-H Amination via Dicopper Nitrenes
Mechanistic Insights into C-H Amination via Dicopper Nitrenes
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DOI：
10.1021/ja400879m
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发表时间：
2013-06-26
影响因子：
15
通讯作者：
Warren, Timothy H.
中科院分区：
文献类型：
--
作者：
Aguila, Mae Joanne B.;Badiei, Yosra M.;Warren, Timothy H.
我们研究了通过可分离的β -二酮胺和二铜烷基亚烯中间体{[Cl2NN]Cu}(2)（mu-NR）进行化学计量和催化C-H胺化的重要反应途径。{[Cl2NN]Cu}(2)(mu-(NBu)- bu -t)(3)对乙苯化学计量胺化反应的动力学研究表明，末端亚硝基[Cl2NN]Cu=(NaBu)- bu -t是C-H胺化反应的活性中间体。初始速率在高乙苯负荷下表现出饱和行为，并且与铜的种类[Cl2NN]Cu呈负相关，这两者都与C-H胺化之前从3中解离[Cl2NN]Cu片段一致。采用1,4-二甲基环己烷和苯基原子钟底物进行的C-H胺化实验支持h原子逐步提取/自由基反弹的途径。由1度和2度烷基化脲衍生的二铜亚胺[Cu](2)（mu-NCHRR‘）对铜(I)亚胺配合物[Cu]（HN=CRR’）不稳定，使得1度和2度烷基亚胺配合物不适合C-H胺化。
We examine important reactivity pathways relevant to stoichiometric and catalytic C-H amination via isolable beta-diketiminato dicopper alkylnitrene intermediates {[Cl2NN]Cu}(2)(mu-NR). Kinetic studies involving the stoichiometric amination of ethylbenzene by {[Cl2NN]Cu}(2)(mu-(NBu)-Bu-t) (3) demonstrate that the terminal nitrene [Cl2NN]Cu=(NaBu)-Bu-t is the active intermediate in C-H 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-H amination. C-H amination experiments employing 1,4-dimethylcyclohexane and benzylic radical clock substrate support a stepwise H-atom abstraction/radical rebound pathway. Dicopper nitrenes [Cu](2)(mu-NCHRR') derived from 1 degrees and 2 degrees alkylazides are unstable toward tautomerization to copper(I) imine complexes [Cu](HN=CRR'), rendering 1 degrees and 2 degrees alkylnitrene complexes unsuitable for C-H amination.