Site‐Selective C-H Alkenylation of N‐Heteroarenes by Ligand‐Directed Co/Al and Co/Mg Cooperative Catalysis**
Site‐Selective C-H Alkenylation of N‐Heteroarenes by Ligand‐Directed Co/Al and Co/Mg Cooperative Catalysis**
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通过配体导向的 Co/Al 和 Co/Mg 协同催化对 N-杂芳烃进行位点选择性 C-H 烯基化**
DOI：
10.1002/anie.202301006
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Yoshikai Naohiko
中科院分区：
文献类型：
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作者：
Saito Yuri;Kikuchi Jun;Wang Chen;Yoshikai Naohiko
我们在此报道了Co/Al和Co/Mg双功能配体负载的膦/仲氧化膦（PSPO）双功能配体催化剂的设计和开发，用于含氮杂芳烃与炔的位点选择性C-H烯基化。这些催化剂能够使吡啶、吡啶酮和咪唑并[1，2-a]吡啶衍生物在靠近刘易斯碱性氮或氧原子的C-H位点处烯基化，这代表了与先前开发的钴-二膦/铝催化剂不同的选择性特征。使用各种杂环和不同取代的内炔以中等至良好的产率获得烯基化产物。动力学同位素效应实验表明C-H活化步骤的不可逆性，其与限速步骤的相关性取决于反应条件。密度泛函理论计算表明，配体间的氢转移是C-H活化的常见机制。
We report herein the design and development of Co/Al and Co/Mg bimetallic catalysts, supported by a phosphine/secondary phosphine oxide (PSPO) bifunctional ligand, for the site‐selective C−H alkenylation of nitrogen‐containing heteroarenes with alkynes. These catalysts enable the alkenylation of pyridine, pyridone, and imidazo[1,2‐a]pyridine derivatives at the C−H site proximal to the Lewis basic nitrogen or oxygen atom, which represents a selectivity profile distinct from that of the previously developed cobalt‐diphosphine/aluminum catalyst. The alkenylated products were obtained in moderate to good yields using various heterocycles and differently substituted internal alkynes. Kinetic isotope effect experiments suggest the irreversibility of the C−H activation step, the relevance of which to the rate‐limiting step depends on the reaction conditions. Density functional theory calculations indicate that ligand‐to‐ligand hydrogen transfer is the common mechanism of C−H activation.