1-Methylimidazolium trifluoroacetate [Hmim]Tfa: Mild and efficient Brønsted acidic ionic liquid for Hantzsch reaction under microwave irradiation

One pot synthesis of 1,4-dihydropyridine derivatives was achieved via condensation of various β -ketoesters with aromatic/aliphatic aldehydes and ammonium acetate. The reaction was catalysed by a stable and reusable Brønsted acidic ionic liquid (IL), 1-methyl-imidazolium trifluoroacetate ([Hmim]Tfa), under microwave (MW) irradiation. The synergistic combination of MW with IL can potentially go a long way to meet the increasing demand for chemical processes. This homogeneous catalytic procedure is simple and efficient. The catalyst can be reused at least four times with almost complete retention in its activity. Graphical Abstract The synthesis of 1,4- dihydropyridine derivatives via Hantzsch reaction induced by combination of microwave energy and ionic liquid is reported. This new protocol requires very mild reaction conditions with water as the only byproduct. The process proved to be simple, environmentally friendly, economic and high yielding.