Direct Base-Assisted C‒H Cyclonickelation of 6-Phenyl-2,2′-bipyridine
Direct Base-Assisted C‒H Cyclonickelation of 6-Phenyl-2,2′-bipyridine
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DOI：
10.3390/molecules25040997
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发表时间：
2020-02
期刊：
影响因子：
4.6
通讯作者：
Nicolas Vogt;V. Sivchik;Aaron Sandleben;G. Hörner;A. Klein
中科院分区：
文献类型：
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作者：
Nicolas Vogt;V. Sivchik;Aaron Sandleben;G. Hörner;A. Klein
首次以NiX 2和HPhbpy（6-苯基-2，2 ′-联吡啶）或多功能前体[Ni（HPhbpy）Br 2]2为原料，通过碱辅助芳烃C（sp2）-H环化反应合成了有机镍配合物[Ni（Phbpy）X]（X = Br，OAc，CN）.不同于以前所需的C Br在Ni（0）的氧化加成，反应条件的扩展扫描允许通过碱辅助的C H在非极性介质中在升高的温度下活化，在合成有用的时间尺度上从Ni（II）定量获得标题化合物。反应条件（各种碱、溶剂、方法）的优化将乙酸盐和碳酸盐的1：2混合物鉴定为最佳方案中无与伦比的协同碱基对，其有望作为易于使用且易于调节的途径获得广泛的直接镍化物产物。虽然对于贵金属Ru、Ir、Rh或Pd的碱辅助C-H金属化，这种醋酸盐/碳酸盐方法已经建立了几年，但我们的研究代表了向3d系列贱金属世界的飞跃。
The organonickel complexes [Ni(Phbpy)X] (X = Br, OAc, CN) were obtained for the first time in a direct base-assisted arene C(sp2)–H cyclometalation reaction from the rather unreactive precursor materials NiX2 and HPhbpy (6-phenyl-2,2′-bipyridine) or from the versatile precursor [Ni(HPhbpy)Br2]2. Different from previously necessary C‒Br oxidative addition at Ni(0), an extended scan of reaction conditions allowed quantitative access to the title compound from Ni(II) on synthetically useful timescales through base-assisted C‒H activation in nonpolar media at elevated temperature. Optimisation of the reaction conditions (various bases, solvents, methods) identified 1:2 mixtures of acetate and carbonate as unrivalled synergetic base pairs in the optimum protocol that holds promise as a readily usable and easily tuneable access to a wide range of direct nickelation products. While for the base-assisted C‒H metalation of the noble metals Ru, Ir, Rh, or Pd, this acetate/carbonate method has been established for a few years, our study represents the leap into the world of the base metals of the 3d series.