Using a nitrogen-centered radical as a selective mediator in electrochemical C(sp3)-H amination
Using a nitrogen-centered radical as a selective mediator in electrochemical C(sp3)-H amination
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DOI：
10.1016/j.checat.2023.100582
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
Yating Liang;X. Zhan;Feng-yun Li;Hong-yan Bi;Weigang Fan;Sheng Zhang;Man‐Bo Li
中科院分区：
文献类型：
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作者：
Yating Liang;X. Zhan;Feng-yun Li;Hong-yan Bi;Weigang Fan;Sheng Zhang;Man‐Bo Li
氮中心自由基是一种用途广泛的中间体，在有机合成中得到了广泛的应用。然而，这些物种的催化作用受到的关注要少得多，因为它们缺乏温和的接触。在这里，我们发现了一系列的氮为中心的自由基，很容易产生的苯并咪唑在直接电解。这些活性物种明确地确定了与电子顺磁共振（EPR），紫外可见（UV-vis）光谱，高分辨率质谱（HRMS）的工具。更重要的是，我们在电化学C（sp3）-H胺化反应中使用了这些原位生成的自由基作为选择性氢原子转移（HAT）介体。在氮中心自由基的调解下，实现了现有方法无法达到的非常规位点选择性和反应性。自由基的催化模式也扩展到醇的烯丙基C（sp3）-H和β-C（sp3）-H的胺化反应、Si-H的阳极氧化反应和Minisci型反应。
Nitrogen-centered radicals are versatile intermediates, and they have been widely explored in organic synthesis. However, the catalytic role of these species has received far less attention due to a dearth of mild access to them. Herein, we discovered an array of nitrogen-centered radicals that were readily generated from benzimidazoles under direct electrolysis. These active species were unambiguously identified with tools of electron paramagnetic resonance (EPR), UV-visible (UV-vis) spectroscopy, and high-resolution mass spectrometry (HRMS). More importantly, we employed thesein-situ-generated radicals in the electrochemical C(sp3)–H aminations as selective hydrogen atom transfer (HAT) mediators. With the mediation of nitrogen-centered radicals, unconventional site selectivity and reactivity were achieved that would otherwise be inaccessible for existing approaches. The catalytic mode enabled by the radicals was also extended to the amination of allylic C(sp3)–H and β-C(sp3)–H of alcohols, anodic oxidation of Si–H, and Minisci-type reactions.