Zwitterionic-Type Molten Salt-Catalyzed Multicomponent Reactions: One-Pot Synthesis of Substituted Imidazoles Under Solvent-Free Conditions

4-(1-Imidazolium) butane sulfonate is an excellent catalyst for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles through the condensation of 1,2-dicarbonyl compounds, aldehydes, and ammonium acetate or amine via multicomponent condensation strategy under solvent-free conditions. The key advantages of this process are high yields, reusability of catalyst, environmental friendliness, easy work-up and purification of products by nonchromatographic methods.