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...
Enantioselective Michael Additions to α,β-Unsaturated Imides Catalyzed by a Salen−Al Complex
作者:Mark S. Taylor、Eric N. Jacobsen
DOI:10.1021/ja037177o
日期:2003.9.1
conjugate addition of di- and trisubstituted nitriles to a wide range of acyclic alkyl- and aryl-substituted α,β-unsaturated imides. This new methodology provides access to multifunctional compounds that previously have not been readily accessible in enantioenriched form. Synthetic applications of these products include the preparation of enantiomerically enriched piperidines, as exemplified by an expedient