Asymmetric Direct Vinylogous Michael Reaction Catalyzed by Self-Assembled Organocatalyst
作者:Wei-Yi Chen、Luo Ouyang、Rui-Ye Chen、Xin-Sheng Li
DOI:10.1080/00397911.2011.563023
日期:2012.9
Abstract The self-assembled organocatalyst of cinchonaalkaloidderivatives and amino acids has been applied to a direct asymmetric vinylogous Michael addition of α,α-dicyanoolefins to nitroolefins; the corresponding products could be obtained in moderate to good yields and enantioselectivities. GRAPHICAL ABSTRACT
chiral thiourea-tertiary amine organocatalysts have been applied to a direct asymmetric vinylogousMichaeladdition 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
Organocatalytic asymmetric allylic carbon–carbon bond formation
作者:Thomas B. Poulsen、Mark Bell、Karl Anker Jørgensen
DOI:10.1039/b514564c
日期:——
bond-forming addition of activated alkylidenes to alkyl and aryl nitroalkenes has been achieved with high diastereo- and enantioselectivity. Chiral tertiary amine catalysts are used to give allyl intermediates which exhibit gamma-selectivity in the C-C bond forming step. The reactions proceed with up to >99:1 syn:anti ratio for both the alkyl- and aryl nitroalkenes with up 96% and 98% ee, respectively
Asymmetric Direct Vinylogous Michael Reaction of Activated Alkenes to Nitroolefins Catalyzed by Modified Cinchona Alkaloids
作者:Dong Xue、Ying-Chun Chen、Qi-Wei Wang、Ling-Feng Cun、Jin Zhu、Jin-Gen Deng
DOI:10.1021/ol052283b
日期:2005.11.1
[reaction: see text] The first organocatalytic and asymmetric directvinylogousMichael reaction that employs the electron-deficient vinyl malononitriles as the nucleophilic species has been reported. The novel transformations exhibit exclusive gamma-selectivity and high diastereo- and enantioselectivity in the addition to nitroolefins, which give the multifunctional products with two vicinal chiral
Construction of Polycyclic Fused Pyrrolidines with Three Contiguous Stereocenters via Michael Addition of Vinylmalononitriles to Nitrostyrenes Using l-Proline-Derived Thiourea
functionalized to achieve the synthesis of polycyclic fused pyrrolidines with three contiguous stereocenters in good enantioselectivities. The catalyticefficiency of a bifunctional chiral thiourea derived from l-proline was evaluated in the asymmetric direct vinylogous Michael reaction of α,α-dicyanoolefins to β-nitrostyrenes with an electron-releasing or electron-withdrawing substituent in various positions