Oxidatively Induced C–H Activation at High Valent Nickel

This communication describes a series of oxidatively induced intramolecular arene C–H activation reactions of NiII model complexes to yield NiIV σ-aryl products. These reactions proceed within 10 min at room temperature, which represents among the mildest conditions reported for C–H cleavage at a Ni center. A combination of density functional theory and preliminary experimental mechanistic studies implicate a pathway involving initial 2e– oxidation of the NiII starting materials by the F+ transfer reagent N-fluoro-2,4,6-trimethylpyridinium triflate followed by triflate-assisted C–H cleavage at NiIV to yield the products.本通讯报道了一系列以二价镍（NiII）模型配合物为底物的氧化诱导分子内芳烃C-H活化反应，可生成四价镍（NiIV）σ-芳基产物。该类反应可在室温下10分钟内完成，是目前已报道的镍中心C-H键裂解反应中条件最为温和的体系之一。结合密度泛函理论（density functional theory）与初步实验机理研究结果，该反应的可行路径被推定如下：首先通过氟正离子转移试剂三氟甲磺酸N-氟-2,4,6-三甲基吡啶鎓对二价镍起始原料进行2电子氧化，随后经三氟甲磺酸根辅助的四价镍中心C-H裂解过程，最终得到目标产物。