Organocatalytic Asymmetric Conjugate Addition of Nitroalkanes to α,β-Unsaturated Enones Using Novel Imidazoline Catalysts
作者:Nis Halland、Rita G. Hazell、Karl Anker Jørgensen
DOI:10.1021/jo0261449
日期:2002.11.1
series of substituted alpha,beta-unsaturated enones with different nitroalkanes. Furthermore, the synthetic applicability of the reaction is demonstrated by the formation of optically active functionalized pyrrolines and pyrrolidines by reductive amination of the products. On the basis of the absolute configuration of the conjugate addition products, the mechanism for the reaction is discussed and a transition
已开发出一种由新型有机催化剂催化的硝基链烷烃向无环α,β-不饱和烯酮的新催化对映选择性共轭加成反应。已经测试了一系列手性胺作为将2-硝基丙烷加到苄叉基丙酮中的催化剂,并且发现由苯丙氨酸制备的新型咪唑啉催化剂可以催化高度对映选择性的1,4-加成反应。发现各种无环和环状硝基烷烃的反应进行得很好,对映选择性高达86%ee,并且可以通过重结晶获得对映纯产物。该反应的潜力通过一系列取代的α,β-不饱和烯酮与不同硝基烷的反应来证明。此外,通过产物的还原胺化形成光学活性的官能化的吡咯啉和吡咯烷,证明了该反应的合成适用性。基于共轭加成产物的绝对构型,讨论了反应机理并提出了过渡态。