Photochemical Radical Cation Cycloadditions of Aryl Vinyl Ethers
Photochemical Radical Cation Cycloadditions of Aryl Vinyl Ethers
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DOI：
10.1002/ejoc.202201207
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发表时间：
2022-11-25
影响因子：
2.8
通讯作者：
Okada, Yohei
中科院分区：
文献类型：
--
作者：
Adachi, Sota;Horiguchi, Genki;Okada, Yohei
自由基阳离子环加成反应长期以来被认为是独特的反应，但在现代合成有机化学领域中却是被广泛研究的化学转化反应。开发这类新反应的关键是高活性自由基阳离子中间体的生成和控制。在这里，我们报道了以芳基乙烯基醚为自由基阳离子前体的TiO2光化学[2+2]和[4+2]环加成反应。这些自由基阳离子的环加成反应使各种四元环和六元环的构造成为可能。尽管详细的机理尚不清楚，但2，3-二甲基-1，3-丁二烯(3)比2-乙基-1-丁烯(2)更亲自由基，并有效地捕获芳基乙烯基醚的自由基阳离子以构建六元环。
Radical cation cycloadditions have long been known as unique reactions and yet are intensively studied chemical transformations in the field of modern synthetic organic chemistry. The key to developing new reactions of this class is the generation and control of highly reactive radical cation intermediates. Herein, we report TiO2 photochemical [2+2] and [4+2] cycloadditions using aryl vinyl ethers as radical cation precursors. The constructions of various four- and six-membered rings are made possible by these radical cation cycloadditions. Although detailed mechanistic aspects remain unclear, 2,3-dimethyl-1,3-butadiene (3) is found to be more radicalophilic than 2-ethyl-1-butene (2) and effectively traps the radical cation of the aryl vinyl ethers to construct six-membered rings.