A magnetic nanoparticle supported dual acidic ionic liquid: a “quasi-homogeneous” catalyst for the one-pot synthesis of benzoxanthenes

A novel magnetic nanoparticle supported dual acidic ionic liquid catalyst was synthesized by anchoring 3-sulfobutyl-1-(3-propyltriethoxysilane) imidazolium hydrogen sulfate onto the surface of silica-coated Fe3O4 nanoparticles. Due to the combination of nano-support features and flexible imidazolium linkers, it acted as a “quasi-homogeneous” catalyst to effectively catalyze the one-pot synthesis of benzoxanthenes by a three-component condensation of dimedone with aldehyde and 2-naphthol under solvent-free conditions. More importantly, the catalyst could be easily recovered by an external magnet and reused six times without significant loss of catalytic activity.