Lewis Acid−Lewis Acid Heterobimetallic Cooperative Catalysis: Mechanistic Studies and Application in Enantioselective Aza-Michael Reaction
作者:Noriyuki Yamagiwa、Hongbo Qin、Shigeki Matsunaga、Masakatsu Shibasaki
DOI:10.1021/ja054066b
日期:2005.9.28
3-3 mol % with enones. To broaden the substrate scope of the reaction to carboxylic acid derivatives, alpha,beta-unsaturated N-acylpyrroles were used as monodentate, carboxylic acid derivatives. With beta-alkyl-substituted N-acylpyrroles, the reaction proceeded smoothly and the products were obtained in high yield and good ee. Transformation of the 1,4-adducts from enones and alpha,beta-unsaturated N-acylpyrroles
描述了由稀土-碱金属异双金属配合物促进的甲氧基胺催化不对称氮杂-迈克尔反应的全部细节,证明了路易斯酸-路易斯酸协同催化的有效性。首先,使用烯酮作为底物,以良好的产率 (57-98%) 和高 ee (81-96%) 获得 1,4-加合物。使用烯酮成功地将催化剂负载降低到 0.3-3 mol%。为了将反应的底物范围扩大到羧酸衍生物,α,β-不饱和 N-酰基吡咯被用作单齿羧酸衍生物。使用β-烷基取代的N-酰基吡咯,反应顺利进行,产物收率高,ee值好。来自烯酮和α的1,4-加合物的转化,β-不饱和N-酰基吡咯得到相应的手性氮丙啶和β-氨基酸。还描述了详细的机械研究,包括动力学、核磁共振分析、非线性效应和稀土金属效应。详细讨论了路易斯酸-路易斯酸协同机制,包括底物配位模式。