Visible Light-Promoted Ring-Opening Alkenylation of Cyclic Hemiacetals through ß-Scission of Alkoxy Radicals
Visible Light-Promoted Ring-Opening Alkenylation of Cyclic Hemiacetals through ß-Scission of Alkoxy Radicals
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可见光促进通过烷氧基自由基断裂实现环状半缩醛的开环烯基化
DOI：
10.1002/cjoc.202200511
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发表时间：
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影响因子：
5.4
通讯作者：
Jianbo Wang
中科院分区：
文献类型：
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作者：
Jiang-Ling Shi;Zixuan Wang;Zeyu He;Bowen Dou;Jianbo Wang
烷氧基自由基的化学在20世纪60年代至90年代期间被广泛探索，但在过去的几十年里一直处于休眠状态。最近，烷氧基自由基再次引起人们的注意，因为新的方法产生烷氧基自由基物种的出现。这些新开发的方法主要基于在温和条件下通过可见光的光解，从而允许由烷氧基的β-断裂或氢夺取产生的碳中心自由基物种的新转化。在此，我们证明了由环状半缩醛衍生的烷氧基自由基可以通过可见光诱导的电子转移与碘化钠和三苯基膦作为催化剂产生。烷氧基随后发生β-断裂，产生碳中心自由基，这些自由基被肉桂酸、芳基烯烃、乙烯基硼酸和甲硅烷基烯醇醚捕获，产生相应的C-C键形成产物。这种用于环状半缩醛衍生物在可见光照射条件下的开环烯基化反应的催化方法证明了可见光促进的烷氧基自由基生成方法与各种碳自由基捕获过程的相容性。这项工作为烷氧基自由基在有机合成中的应用开辟了新的可能性。
The chemistry of alkoxy radicals was extensively explored during the period of 1960s to 1990s, but it has remained dormant for the past few decades. Recently, alkoxy radicals attract the attentions again, because new methods for generating alkoxy radical species have emerged. These newly developed methods are mainly based on the photolysis by visible light under mild conditions, thus allowing for new transformations of the carbon-centered radical species that are generated from the β-scission or hydrogen abstraction of the alkoxy radicals. Herein, we demonstrate that the alkoxy radicals derived from cyclic hemiacetals can be generated through visible-light-induced electron transfer with sodium iodide and triphenylphosphine as the catalyst. The alkoxy radicals subsequently undergo β-scission to generate carbon-centered radicals, which are trapped by cinnamic acids, aryl alkenes, vinylboronic acid and silyl enol ether to deliver the corresponding C—C bond forming products. This catalytic method for ring-opening alkenylation reaction of cyclic hemiacetal derivatives under visible-light irradiation conditions demonstrates the compatibility of the visible light-promoted alkoxy radical generation method with various carbon radical trapping processes. This work opens up new possibilities for the application of alkoxy radicals in organic synthesis.