Catalytic, Enantioselective, Intramolecular Sulfenofunctionalization of Alkenes with Phenols.
Catalytic, Enantioselective, Intramolecular Sulfenofunctionalization of Alkenes with Phenols.
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DOI：
10.1021/acs.joc.7b00295
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发表时间：
2017-03-17
期刊：
影响因子：
--
通讯作者：
Kornfilt DJ
中科院分区：
文献类型：
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作者：
Denmark SE;Kornfilt DJ
酚类与亲电磺基邻苯二甲酰亚胺在孤立或共轭烯烃上的催化、对映选择性环化反应得到2，3-二取代苯并吡喃和苯并氧杂环庚三烯。该反应由基于BINAM的磷酰胺刘易斯碱催化剂催化，该催化剂有助于硫杂环丁烷离子中间体的高度对映选择性形成。研究了亲核电子密度、烯烃取代方式、链长和刘易斯碱官能团对环化反应速率、对映体选择性和位点选择性的影响。反应不受酚环上取代基的影响。相反，烯烃周围的取代强烈影响反应结果。系链的连续延长导致反应性降低，这需要增加反应发生的温度。在这些升高的温度下，氧硫基部分上的空间体积庞大的芳基防止对映体组合物的侵蚀。醇和羧酸优先捕获硫杂环丁烷离子与酚羟基竞争。还描述了一种改进的酚类选择性C（2）烯丙基化方法。
The catalytic, enantioselective, cyclization of phenols with electrophilic sulfenophthalimides onto isolated or conjugated alkenes affords 2,3-disubstituted benzopyrans and benzoxepins. The reaction is catalyzed by a BINAM-based phosphoramide Lewis base catalyst which assists in the highly enantioselective formation of a thiiranium ion intermediate. The influence of nucleophile electron density, alkene substitution pattern, tether length and Lewis base functional groups on the rate, enantio- and site-selectivity for the cyclization is investigated. The reaction is not affected by the presence of substituents on the phenol ring. In contrast, substitutions around the alkene strongly affect the reaction outcome. Sequential lengthening of the tether results in decreased reactivity, which necessitated increased temperatures for reaction to occur. Sterically bulky aryl groups on the sulfenyl moiety prevented erosion of enantiomeric composition at these elevated temperatures. Alcohols and carboxylic acids preferentially captured thiiranium ions in competition with phenolic hydroxyl groups. An improved method for the selective C(2) allylation of phenols is also described.