Sulfamic acid functionalised magnetic nanoparticles: an efficient solid acid for the multicomponent condensations

Sulfamic acid-functionalised magnetic nanoparticles have been synthesised and used as efficient heterogeneous solid acid catalysts for the condensation of aromatic aldehydes with 2-naphthol and amides (or carbamates) via three-component reactions under solvent-free conditions at 80 degrees C. Quantitative conversion of the reactants is achieved under mild conditions. Recovery of the catalyst is easily achieved by 'magnetic decantation'. The supported catalyst is reused four times without any significant degradation in catalytic activity.