Rh<sub>2</sub>(<i>R</i>-TPCP)<sub>4</sub>-Catalyzed Enantioselective [3+2]-Cycloaddition between Nitrones and Vinyldiazoacetates
作者:Changming Qin、Huw M. L. Davies
DOI:10.1021/ja4069003
日期:2013.10.2
Rhodium-catalyzed reaction of vinyldiazoacetates with nitrones results in a formal [3+2]-cycloaddition to generate 2,5-dihydroisoxazoles with high levels of asymmetric induction. The cascade reaction begins with a vinylogous addition event, followed by an iminium addition ring-closure/hydride migration/alkene isomerization cascade. Dirhodium tetrakis(triarylcyclopropanecarboxylates) are the optimum
乙烯基重氮乙酸酯与硝酮的铑催化反应导致正式的 [3+2]-环加成反应生成具有高水平不对称诱导的 2,5-二氢异恶唑。级联反应以乙烯基加成事件开始,然后是亚胺加成闭环/氢化物迁移/烯烃异构化级联反应。四(三芳基环丙烷羧酸盐)铑是该工艺的最佳催化剂。