C–H amination reactions are valuable transformations for the construction of C–N bonds. Due to their relatively high bond dissociation energies, C(sp²)–H bonds are generally not susceptible toward direct nitrene insertion, necessitating alternative mechanisms for C–H activation. Here, we report that cationic dinuclear (NDI)Ni₂ (NDI = naphthyridine–diimine) complexes catalyze intramolecular nitrene insertions into aryl and vinyl C(sp²)–H bonds. Mechanistic studies suggest that a bridging imido ligand supported at a Ni₂ site induces C–H activation by a 1,2-addition pathway to generate an azametallacyclic intermediate. This organometallic mechanism contrasts with the electrocyclization/1,2-shift mechanism proposed for analogous transformations using Rh₂ catalysts. The implications of these mechanistic differences for the stereoselectivity and chemoselectivity of C–H amination are described.

中文翻译：

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^双镍酰亚胺催化的C（sp ²）–H胺化反应

C–H氨基化反应是C–N键结构的重要转化。由于它们相对较高的键解离能，C（sp ²）–H键通常不易直接插入氮，因此需要替代的C–H活化机制。在这里，我们报告阳离子双核（NDI）Ni ₂（NDI =萘啶-二亚胺）络合物催化分子内氮插入到芳基和乙烯基C（sp ²）-H键中。机理研究表明，桥接的亚氨基配体负载在Ni _2上该位点通过1，2-加成途径诱导CH活化，生成氮杂金属环中间体。该有机金属机理与为使用Rh ₂催化剂进行类似转化而提出的电环化/ 1,2-转移机理相反。这些机理差异对C–H胺的立体选择性和化学选择性的影响进行了描述。