Bromine-radical-induced C sp2–H difluoroalkylation of quinoxalinones and hydrazones through visible-light-promoted Csp3–Br bond homolysis
Bromine-radical-induced C sp2–H difluoroalkylation of quinoxalinones and hydrazones through visible-light-promoted Csp3–Br bond homolysis
复制标题
通过可见光促进的 Csp3-Br 键均裂，溴自由基诱导喹喔啉酮和腙的 C sp2-H 二氟烷基化
DOI：
10.1039/d2qo00710j
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Gui-Ting Song
中科院分区：
文献类型：
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作者：
Chuanhua Qu;Run Huang;Yuan Liu;Tong Liu;Gui-Ting Song
本文公开了一种用于喹喔啉酮和腙与溴二氟酰基芳烃通过可见光促进的Csp 3-Br键均裂途径的直接C-H二氟烷基化的无光敏剂策略。该新反应提供了在简单、温和、绿色和无金属条件下获得具有优异底物通用性的二氟烷基化喹喔啉和腙衍生物的途径。该方法利用了溴二氟酰基芳烃在Csp 3-Br键均裂中形成二氟烷基自由基和溴自由基物质的迷人的光化学活性。所产生的溴自由基可直接从喹烯酮和腙介导H夺取/亚胺自由基形成，其继而淬灭原位产生的二氟烷基自由基以提供产物。值得注意的是，这是溴自由基通过可见光诱导的Csp 3-Br键均裂在有机转化中应用的第一个例子。此外，烷基溴介导的光化学Csp 3-Br键均裂的最低结构要求进行了研究。
Disclosed herein is a photosensitizer-free strategy for the direct C–H difluoroalkylation of quinoxalinones and hydrazones with bromodifluoroacylarenes via a visible-light-promoted Csp3–Br bond homolytic pathway. This new reaction provides access to difluoroalkylated quinoxaline and hydrazone derivatives with excellent substrate generality under simple, mild, green, and metal-free conditions. This process exploits the fascinating photochemical activity of bromodifluoroacylarenes in the homolysis of Csp3–Br bonds to form difluoroalkyl radicals and bromine radical species. The generated bromine radicals can.mediate H abstraction/imine radical formation directly from quinoxalinones and hydrazones, which in turn quench the in situ-generated difluoroalkyl radicals to furnish the products. It is of note is that this is the first example of the application of bromine radicals in organic transformation via Csp3–Br bond homolysis induced by visible light. Moreover, the minimal structural requirements for alkyl bromide-mediated photochemical Csp3–Br bond homolysis were investigated.