N‐Heterocyclic Carbene Catalyzed Synthesis of δ‐Sultones via α,β‐Unsaturated Sulfonyl Azolium Intermediates
作者:Andrei Ungureanu、Alison Levens、Lisa Candish、David W. Lupton
DOI:10.1002/anie.201504633
日期:2015.9.28
A limited array of reactive intermediates have enabled a wealth of discoveries in N‐heterocyclic carbene organocatalysis. In this study, the viability of α,β‐unsaturated sulfonyl azoliums as double electrophiles in new reactions is examined. Specifically, the (3+3) annulation of such species with the trimethylsilyl enol ethers of various 1,3‐dicarbonyl compounds has been developed. This reaction provides
数量有限的反应性中间体已在N杂环卡宾有机催化中获得了许多发现。在这项研究中,研究了α,β-不饱和磺酰基偶氮在新反应中作为双亲电子试剂的可行性。特别是,已经开发了用各种1,3-二羰基化合物的三甲基甲硅烷基烯醇醚将这类物质(3 + 3)环化的方法。在温和的反应条件下,该反应可以以较高的收率(40–88%)获得一系列新型不饱和δ-磺内酯(18个实例)。机理研究和对映选择性变体的开发(55%收率,73:27 er)支持了α,β-不饱和磺酰基偶氮鎓物种的中介作用。