One-Pot, Enantioselective Synthesis of 2,3-Dihydroazulen-6(1<i>H</i>)-one: A Concise Access to the Core Structure of<i>Cephalotaxus</i>Norditerpenes
作者:Yongsheng Zheng、Ebrahim H. Ghazvini Zadeh、Yu Yuan
DOI:10.1002/ejoc.201600321
日期:2016.4
A one-pot enantioselective synthesis of cis-substituted 2,3-dihydroazulen-6(1H)-one is described. In this cascade reaction, an organocatalyzed asymmetric Michael reaction furnishes a highly optically pure nitrobutylphenol intermediate, which is converted into an annulated tropone species by sequential oxidative dearomatization, conjugate addition, electrocyclic ring opening and nitrous acid elimination
描述了顺式取代的 2,3-dihydroazulen-6(1H)-one 的一锅对映选择性合成。在该级联反应中,有机催化的不对称迈克尔反应提供了高度光学纯的硝基丁基苯酚中间体,通过在同一反应容器中依次进行氧化脱芳构化、共轭加成、电环开环和亚硝酸消除,将其转化为环化的托酮类物质。脂肪族和芳香族硝基烯烃都是一锅反应的良好底物,该协议似乎也适用于各种苯丙醛。在不对称取代的苯丙醛的情况下,区域选择性可能由取代基的空间和电子特性决定。