Catalyst-free, one-pot, four-component green synthesis of functionalized 1-(2-fluorophenyl)-1,4-dihydropyridines under ultrasound irradiation

An environmentally friendly catalyst-free synthesis protocol for functionalized 1,4-dihydropyridine derivatives involving four components under ultrasonic irradiation in aqueous ethanol is reported. Eleven new compounds are synthesized using multi-component one-pot reaction between dimethylacetylenedicarboxylate, 2-fluoroaniline, malononitrile and various substituted aldehydes. The establishment of multiple carbon-carbon bonds occurs in the absence of any hazardous organic solvents or catalysts. The target compounds were obtained in excellent yields (89-96%). All the new compounds were identified and validated by IR, H-1 NMR, C-13 NMR, F-19 NMR, N-15 NMR and HRMS spectral data. The new procedure has noteworthy advantages including safety, short reaction times, environmentally benign mild conditions and high yields.