Base-Mediated Tandem 1,6-Addition/Cyclization/Isomerization Reactions between para-Quinone Methides and Benzyl Chlorides: Approaches to Diverse Frameworks at Each Cascade Stage
作者:Shangkun Zhao、Yuanyuan Zhu、Minli Zhang、Xixi Song、Junbiao Chang
DOI:10.1055/s-0037-1610691
日期:2019.5
Abstract Base-mediated stereospecific tandem reactions using para-quinone methides and carbene-like benzyl chlorides are developed. DBU-mediated 1,6-addition/cyclization/isomerization reactions produce triarylsubstituted alkenes in 43–89% yields and Z/E ratios of 5:1 to 35:1 in favor of the Z-isomers. Single-step 1,6-conjugate additions are realized with the mediation of cesium carbonate, and different
抽象的 开发了使用对苯醌甲基化物和卡宾样苄基氯的碱介导的立体有序串联反应。DBU介导的1,6-加成/环化/异构化反应产生三芳基取代的烯烃,产率为43-89%,Z / E比为5:1至35:1,有利于Z-异构体。在碳酸铯的介导下,一步法加成1,6-共轭物即可获得不同的三芳基氯乙烷,收率为41–54%,非对映异构体选择性超过20:1。另外,使用调节的2,4-二取代的苄基氯实现串联的1,6-加成/环化反应,得到二芳基螺环环丙基对-二烯酮的收率在35-83%之间,非对映选择性超过20:1,有利于抗异构体。来自三芳基chloroethanes和螺环的转变对-dienones到triarylsubstituted烯烃也证明支持拟议的串联机制。 开发了使用对苯醌甲基化物和卡宾样苄基氯的碱介导的立体有序串联反应。DBU介导的1,6-加成/环化/异构化反应产生三芳基取代的烯烃,产率为43-89%,Z / E比