Catalyst- and Substituent-Controlled Switching of Chemoselectivity for the Enantioselective Synthesis of Fully Substituted Cyclobutane Derivatives via 2 + 2 Annulation of Vinylogous Ketone Enolates and Nitroalkene
作者:Pavan Sudheer Akula、Bor-Cherng Hong、Gene-Hsiang Lee
DOI:10.1021/acs.orglett.8b03335
日期:2018.12.21
The first regioselective, diastereoselective, and enantioselective organocatalyzed Michael–Michael cascade of vinylogous ketone enolates and nitroalkenes for the construction of fully substituted cyclobutanes is achieved by the deployment of the appropriate chiral squaramide catalyst and the pertinent substituent on the substrate. The domino reaction provided cyclobutanes with four contiguous stereocenters
通过将适当的手性方酸酰胺催化剂和相关的取代基部署在基材上,可以实现第一个区域选择性,非对映选择性和对映选择性有机催化迈克尔-迈克尔级联的乙烯基酮烯醇烯酸酯和硝基烯烃,以构建完全取代的环丁烷。多米诺反应为环丁烷提供了四个连续的立体中心,包括一个具有高收率的四元中心,其非对映体比率> 20:1,对映选择性最多可达98%对映体过量(ee)。加合物的结构和绝对构型通过适当产物的单晶X射线晶体学分析证实。