title: Ultrasound-mediated synthesis of 4-substituted 1,4-dihydropyridine-3,5-dicarboxylates catalyzed by 1-carboxymethyl-3-methylimidazolium tetrafluoroborate under solvent free condition.
abstract: 4-Substituted 1,4-dihydropyridine-3,5-dicarboxylates (4) have been synthesized by the solvent-free reaction of aldehyde, methyl propiolate and ammonium carbonate catalyzed by ionic liquid 1-carboxymethyl-3-methylimidazolium tetrafluoroborate under ultrasonic irradiation. The effects of changes in the ultrasonic power, temperature, catalysts and reactants on the synthesis of 4-substituted 1,4-dihydropyridine-3,5-dicarboxylates (4) are discussed. With the optimized reaction conditions, various aldehydes were used to synthesize 1,4-dihydropyridines (4) under the influence of ultrasound irradiation. Compared with the conventional thermal methods, the remarkable advantages of this method are the simple experimental procedure, shorter reaction time (2-10min) and high yield of product (76-95%). Furthermore, the green catalytic system can be recycled specific times without significantly decreasing the yields and reaction rates.
authors: College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China. Electronic address: jyhe@emails.bjut.edu.cn.
authors: Jing-Yu
authors: JY
authors: He
authors: College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China.
authors: Hui-Zhen
authors: HZ
authors: Jia
authors: College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China.
authors: Qing-Guo
authors: QG
authors: Yao
authors: College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China.
authors: Si-Jie
authors: SJ
authors: Liu
authors: College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China.
authors: Hong-Kun
authors: HK
authors: Yue
authors: College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China.
authors: Hong-Wei
authors: HW
authors: Yu
authors: College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, China.
authors: Rui-Sheng
authors: RS
authors: Hu
keywords: 4-Substituted 1,4-dihydropyridine-3,5-dicarboxylates; Ionic liquid; Synthesis; Ultrasound