Fe3O4@SiO2•HM•SO3H as a recyclable heterogeneous nanocatalyst for the microwave-promoted synthesis of 2,4,5-trisubstituted imidazoles under solvent free conditions

A simple, highly versatile and efficient synthesis of 2,4,5-trisubstituted imidazoles is achieved through a three component one pot reaction of benzil, benzaldehyde and NH4OAc. This reaction has been catalyzed by Fe3O4@SiO2 center dot HM center dot SO3H, a very efficient, novel recyclable heterogeneous catalyst, under microwave irradiation and solvent free conditions. The catalyst can be recovered for the subsequent reactions and reused for at least five rounds, without any appreciable loss of its efficiency.