Thiourea-Catalyzed Asymmetric Michael Addition of Activated Methylene Compounds to α,β-Unsaturated Imides: Dual Activation of Imide by Intra- and Intermolecular Hydrogen Bonding
A thiourea-catalyzed asymmetricMichaeladdition of activated methylene compounds to α,β-unsaturated imides derived from 2-pyrrolidinone and 2-methoxybenzamide has been developed. In the case of 2-pyrrolidinone derivatives, the reaction with malononitrile proceeded in toluene with high enantioselectivity, providing the Michael adducts in good yields. However, the nucleophiles that could be used for
已开发出硫脲催化的活化亚甲基化合物与衍生自 2-吡咯烷酮和 2-甲氧基苯甲酰胺的 α,β-不饱和酰亚胺的不对称迈克尔加成反应。在 2-吡咯烷酮衍生物的情况下,与丙二腈的反应在甲苯中以高对映选择性进行,以良好的收率提供迈克尔加合物。然而,由于底物的反应性差,可用于该反应的亲核试剂仅限于丙二腈。进一步的研究表明,在芳环上带有不同取代基的相应苯甲酰胺衍生物中,N-链烯酰基-2-甲氧基苯甲酰胺是最好的底物。事实上,几种活化的亚甲基化合物如丙二腈、α-氰基乙酸甲酯、硝基甲烷可用作亲核试剂,以良好至极好的收率获得高达 93% ee 的迈克尔加合物。光谱实验的结果表明,这种增强的反应性可归因于分子内氢...