Substituted α-Alkylidene Cyclopentenones via the Intramolecular Reaction of Vinyl Cations with Alkenes
Substituted α-Alkylidene Cyclopentenones via the Intramolecular Reaction of Vinyl Cations with Alkenes
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DOI：
10.1021/acs.orglett.9b04255
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发表时间：
2020-01-17
期刊：
影响因子：
5.2
通讯作者：
Brewer, Matthias
中科院分区：
文献类型：
--
作者：
Hensinger, Magenta J.;Dodge, Nicholas J.;Brewer, Matthias
取代的α-亚烷基环戊酮是通过与侧链烯烃分子内捕获乙烯基阳离子而生成的，产率高达93%。β-羟基-α-重氮酮起始物质在β-羟基-α-重氮酮的β-位上的取代程度增加，改变了反应的进程，转而得到内酯产品。提出了一种通过酰基离子中间体进行键重组的反应路径来解释这些结果。底物范围的研究表明，越稳定的乙烯基阳离子可以得到更高的α-亚烷基环戊酮的产率。本研究提供了一种温和而有效的方法来合成α-亚烷基环戊酮，以补充C-H插入和纳扎罗夫环化策略。
Substituted alpha-alkylidene cyclopentenones are formed in up to 93% yield by the intramolecular capture of vinyl cations with pendent alkenes. An increased level of substitution at the beta-position of the beta-hydroxy-alpha-diazoketone starting material changed the course of the reaction to instead give a lactone product. A reaction path that involves bond reorganization via an acylium ion intermediate is proposed to explain these results. Substrate scope studies showed that more stable vinyl cations gave higher alpha-alkylidene cyclopentenone yields. This study provides a mild and efficient method to form alpha-alkylidene cyclopentenones that complements C-H insertion and Nazarov cyclization strategies.