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Chan–Evans–Lam Couplings with Copper Iminoarylsulfonate Complexes: Scope and Mechanism
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-06-25 00:00:00 , DOI: 10.1021/acscatal.8b01881 Valérie Hardouin Duparc 1 , Guillaume L. Bano 1 , Frank Schaper 1
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-06-25 00:00:00 , DOI: 10.1021/acscatal.8b01881 Valérie Hardouin Duparc 1 , Guillaume L. Bano 1 , Frank Schaper 1
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Copper(II) pyridyliminoarylsulfonate complexes with chloride or triflate counteranions were employed in Chan–Evans–Lam (CEL) couplings of N-nucleophiles and arylboronic acids. The complexes avoided typical side reactions in CEL couplings, and an excess of boronic acid was not required. Water was tolerated, and addition of neither base nor other additives was necessary. Primary amines, acyclic and cyclic secondary amines, anilines, aminophenol, imidazole, pyrazole, and phenyltetrazole can be quantitatively arylated at either 25 or 50 °C with 2.5 mol % of the catalyst. Reaction kinetics were investigated in detail. Kinetic and spectroscopic studies provide evidence for the formation of unproductive copper–substrate complexes. Formation of an aniline–phenylboronic acid adduct was responsible for the zero-order dependence of reaction rates on phenylboronic acid concentration. Kinetic evidence indicates that the order of reaction steps is transmetalation, nucleophile coordination, and oxidation. Couplings performed poorly with electron-deficient arylboronic acids, due to a slower Cu(II)/Cu(III) oxidation in the catalytic cycle. Photoredox catalysis partially resolved this problem, but addition of copper acetate as an external oxidant proved to be more efficient.
中文翻译：
Chan-Evans-Lam与氨基芳基磺酸铜络合物的偶联：范围和机理
N-亲核试剂和芳基硼酸的Chan-Evans-Lam（CEL）偶联反应中使用了吡啶（氯）吡啶基亚氨基磺酸磺酸铜与三氟甲磺酸酯或三氟甲磺酸酯抗衡离子的配合物。该络合物避免了CEL偶联中的典型副反应，并且不需要过量的硼酸。可以耐受水，并且不需要添加碱或其他添加剂。伯胺，无环和环状仲胺，苯胺，氨基苯酚，咪唑，吡唑和苯基四唑可以在25或50°C下用2.5 mol％的催化剂定量芳基化。详细研究了反应动力学。动力学和光谱学研究为形成非生产性的铜-底物复合物提供了证据。苯胺-苯硼酸加合物的形成是反应速率对苯硼酸浓度的零级依赖性的原因。动力学证据表明，反应步骤的顺序是金属转移，亲核配位和氧化。由于催化循环中较慢的Cu（II）/ Cu（III）氧化，偶联剂与缺电子的芳基硼酸的偶联性能较差。光氧化还原催化部分解决了这个问题，但事实证明添加乙酸铜作为外部氧化剂更为有效。
更新日期：2018-06-25
中文翻译：
Chan-Evans-Lam与氨基芳基磺酸铜络合物的偶联：范围和机理
N-亲核试剂和芳基硼酸的Chan-Evans-Lam（CEL）偶联反应中使用了吡啶（氯）吡啶基亚氨基磺酸磺酸铜与三氟甲磺酸酯或三氟甲磺酸酯抗衡离子的配合物。该络合物避免了CEL偶联中的典型副反应，并且不需要过量的硼酸。可以耐受水，并且不需要添加碱或其他添加剂。伯胺，无环和环状仲胺，苯胺，氨基苯酚，咪唑，吡唑和苯基四唑可以在25或50°C下用2.5 mol％的催化剂定量芳基化。详细研究了反应动力学。动力学和光谱学研究为形成非生产性的铜-底物复合物提供了证据。苯胺-苯硼酸加合物的形成是反应速率对苯硼酸浓度的零级依赖性的原因。动力学证据表明，反应步骤的顺序是金属转移，亲核配位和氧化。由于催化循环中较慢的Cu（II）/ Cu（III）氧化，偶联剂与缺电子的芳基硼酸的偶联性能较差。光氧化还原催化部分解决了这个问题，但事实证明添加乙酸铜作为外部氧化剂更为有效。
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