Aerobic C–C and C–O bond formation reactions mediated by high-valent nickel species
Aerobic C–C and C–O bond formation reactions mediated by high-valent nickel species
复制标题
高价镍物种介导的需氧 C–C 和 C–O 键形成反应
DOI：
10.1039/c9sc03758f
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发表时间：
2019
期刊：
影响因子：
8.4
通讯作者：
Mirica, Liviu M.
中科院分区：
文献类型：
--
作者：
Smith, Sofia M.;Planas, Oriol;Gómez, Laura;Rath, Nigam P.;Ribas, Xavi;Mirica, Liviu M.
镍配合物已被广泛用作C-C和C-杂原子键形成反应的催化剂。虽然Ni（0）、Ni（I）和Ni（II）中间体在这些转化中最相关，但最近Ni（III）和Ni（IV）物种也被提出在催化中发挥作用。本文报道了一系列由具有各种N-取代基的四齿吡啶并吡喃配体稳定的Ni（II）和Ni（III）金属配合物的合成、详细表征和反应性。有趣的是，虽然与各种其他氧化剂的Ni（II）络合物的氧化导致排他性的C-C键形成在非常好的产率，使用O2或H2 O2作为氧化剂导致形成可观的量的C-O键形成产物，特别是对于Ni（II）络合物由含有一个甲苯磺酰基N-取代基的不对称吡啶并吡喃配体支持。此外，cryo-ESI-MS研究支持在这种不常见的Ni介导的加氧酶型化学中形成几种高价Ni物质作为关键中间体。
Nickel complexes have been widely employed as catalysts in C–C and C–heteroatom bond formation reactions. While Ni(0), Ni(I), and Ni(II) intermediates are most relevant in these transformations, recently Ni(III) and Ni(IV) species have also been proposed to play a role in catalysis. Reported herein is the synthesis, detailed characterization, and reactivity of a series of Ni(II) and Ni(III) metallacycle complexes stabilized by tetradentate pyridinophane ligands with various N-substituents. Interestingly, while the oxidation of the Ni(II) complexes with various other oxidants led to exclusive C–C bond formation in very good yields, the use of O2 or H2O2 as oxidants led to formation of appreciable amounts of C–O bond formation products, especially for the Ni(II) complex supported by an asymmetric pyridinophane ligand containing one tosyl N-substituent. Moreover, cryo-ESI-MS studies support the formation of several high-valent Ni species as key intermediates in this uncommon Ni-mediated oxygenase-type chemistry.