Asymmetric direct vinylogous carbon–carbon bond formation catalyzed by bifunctional organocatalysts
作者:Lin Jiang、Hong-Ting Zheng、Tian-Yu Liu、Lei Yue、Ying-Chun Chen
DOI:10.1016/j.tet.2007.04.011
日期:2007.6
chiral thiourea-tertiary amine organocatalysts have been applied to a direct asymmetric vinylogous Michael addition of α,α-dicyanoolefins to nitroolefins with 2–10 mol % catalyst loadings. The electronic properties of the thiourea-based catalysts have significant influences on this reaction. Moderate to excellent enantioselectivities (57–95% ee) have been achieved with low to good isolated yields through
双功能手性硫脲-叔胺有机催化剂已被用于将α,α-二氰基烯烃直接不对称乙烯基迈克尔加成到催化剂负载量为2-10 mol%的硝基烯烃中。硫脲基催化剂的电子性质对该反应有重大影响。通过微调双功能有机催化剂的结构,已实现中等至优异的对映选择性(57-95%ee),分离产率低至良好。与经修饰的金鸡纳生物碱催化的底物相比,某些α,α-二氰基烯烃底物获得了更好的ee。