Michael addition of active methylene compounds toα,β-unsaturated carboxylic esters and nitriles was effectively catalyzed by a basic ionic liquid,1-butyl-3-methylimidazolium acetate([Bmim]OAc).The bis-addition products were selectively obtained in high yields under miLd reaction conditions.
YANG Yu WANG Li-bing ZHANG Zhan LI Cai-meng FU Xian-lei GAO Guo-hua
A series of novel imidazolium based ionic liquids containing the urea moiety were designed and synthesized for anion recognition. 1-Ethylurea-3-methylimidazolium acetate ([Eumim]OAc) was used as the receptor for the halides and complex anions (BF4-, PF6-, BPh4-). 1H NMR spectra showed that the urea protons and imidazolium C(2) proton of the receptor ([Eumim]OAc) moved upfield on addition of various anions. A Job plot showed that the [Eumim]OAc receptor formed a 1:1 complex with BPh4-. X-ray diffraction analysis and the molecular modeling study revealed that the conformations of [Eumim]OAc and [Eumim]BPh4 were different. The conformational change of the cation was caused by anion exchange, and may provide an alternative to current methods for recognition of anions.
