Obata Atsushi, Sasagawa Akane, Yamazaki Ken, Ano Yusuke, Chatani Naoto
Department of Applied Chemistry , Faculty of Engineering , Osaka University , Suita , Osaka 565-0871 , Japan . Email:
Chem Sci. 2019 Feb 4;10(11):3242-3248. doi: 10.1039/c8sc05063e. eCollection 2019 Mar 21.
The reaction of N-heteroaromatic compounds, such as 2-aryl-pyrrole, benzimidazole, imidazole, indole, and pyrazole derivatives, with alkynes in the presence of a catalytic amount of a nickel complex results in C-H/N-H oxidative annulation. The reaction shows a high functional group compatibility. While both Ni(0) and Ni(ii) complexes show a high catalytic activity, Ni(0) is proposed as a key catalytic species in the main catalytic cycle. In the case of the Ni(ii) system, the presence of a catalytic amount of a strong base, such as KOBu , is required for the reaction to proceed. In sharp contrast, a base is not required in the case of the Ni(0) system. The proposed mechanism is supported by DFT studies.
在催化量的镍配合物存在下，N-杂芳族化合物（如2-芳基吡咯、苯并咪唑、咪唑、吲哚和吡唑衍生物）与炔烃反应会导致C-H/N-H氧化环化。该反应具有高官能团兼容性。虽然Ni(0)和Ni(ii)配合物均显示出高催化活性，但Ni(0)被认为是主要催化循环中的关键催化物种。在Ni(ii)体系中，反应进行需要催化量的强碱（如叔丁醇钾）存在。与之形成鲜明对比的是，Ni(0)体系中不需要碱。所提出的机理得到了密度泛函理论研究的支持。
