The asymmetric domino Michael-SN2 reaction of various 1,3-dicarbonyl compounds to α-bromonitroalkenes is described for the first time, employing readily available cinchona-derived bifunctionalthioureas as organocatalysts. The novel transformations were highly regio-, chemo-, diastereo-, and enantioselective, which simultaneously gave the chiral tricyclic 2,3-dihydrofurans, bicyclic 2,3-dihydrofurans
Asymmetricorganocatalyticdomino type Michael-SN2 reactions give access to enantiomerically enriched dihydrofuran derivatives that can be used as valuable chiral building blocks. A variety of α-bromonitroalkenes and 1,3-dicarbonyl compounds were allowed to react under optimized conditions, in the presence of a bifunctional quinine-derived sterically encumbered squaramide (H-bond donor) organocatalyst
不对称有机催化多米诺骨牌型 Michael-S N 2 反应提供了对映异构富集的二氢呋喃衍生物,可用作有价值的手性构件。在双功能奎宁衍生的空间位阻方酸酰胺(H 键供体)有机催化剂的存在下,允许各种 α-溴硝基烯烃和 1,3-二羰基化合物在优化条件下反应。本文中开发的条件在反应持续时间(1-6 小时vs. 24-96 小时)和反应温度(室温vs. -20 °C 至 -50 °C )方面优于文献中已知的方法) 产生具有高达 97% ee 的良好对映选择性的非对映选择性产物。