Synthesis of dihydropyridines and quinoxaline derivatives using 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium chloride as a new, reusable and efficient Bronsted acidic ionic liquid catalyst

Abstract

In this work, the efficiency, generality and applicability of new silica supported Brønsted acidic ionic liquid (BAIL) 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium chloride as heterogeneous and green catalyst for organic transformations are studied. Herein, the following one-pot multi-component reactions in the presence of [Msei]Cl are investigated: (i) the synthesis of quinoxaline derivatives from phenylendiamine and 1,2-diketones in EtOH and under mild conditions (room temperature), (ii) the preparation of 1,4-dihydropyridines from one-pot multi component condensation of 1,3-dicarbonyl compounds(2 equiv.), NH4OAc (1.5 equiv.) and aldehydes (1 equiv.) under solvent-free conditions at moderate temperature (90 °C). High yields, relatively short reaction times, efficiency, generality, clean process, simple methodology, low cost, easy work-up, ease of preparation and regeneration of the catalyst and green conditions (in the synthesis of the quinoxaline derivatives) are advantages of the application of [Mesi]Cl as catalyst in the above organic reactions.