Chiral Ionic Liquids Bearing O-Silylated α,α-Diphenyl (S)- or (R)-Prolinol Units: Recoverable Organocatalysts for Asymmetric Michael Addition of Nitroalkanes to α,β-Enals
作者:Oleg V. Maltsev、Alexandr S. Kucherenko、Irina P. Beletskaya、Vladimir A. Tartakovsky、Sergei G. Zlotin
DOI:10.1002/ejoc.201000239
日期:2010.5
Chiral ionic liquids bearing O-silylated α,α-diphenyl (S)- or (R)-prolinol units tagged to the imidazolium cation were synthesized and their activity as catalysts in the Michael addition of nitroalkanes to α,β-unsaturated aldehydes was evaluated. Respective (S) or (R) adducts were obtained in the reactions in high yields (up to 95 %) and with high enantioselectivity (up to 99 % ee). Remarkably, the
合成了带有标记到咪唑鎓阳离子的 O-甲硅烷基化 α,α-二苯基 (S)-或 (R)-脯氨醇单元的手性离子液体,并评估了它们在硝基烷烃与 α,β-不饱和醛的迈克尔加成反应中作为催化剂的活性. 在反应中以高产率(高达 95%)和高对映选择性(高达 99%ee)获得了相应的 (S) 或 (R) 加合物。值得注意的是,固定化的有机催化剂可以使用五次而不会降低产品产率或 ee 值。(R)-Michael 加合物可以很容易地转化为药物 Phenibut、巴氯芬和咯利普兰的最活跃的 (R) 对映异构体,用于治疗中枢神经系统疾病。