Fe3O4@SiO2–SO3H core-shell nanoparticles: a highly active and easily recyclable catalyst for the synthesis of 7-alkyl-6H,7H-naphtho[1',2':5,6]pyrano[3,2 c]chromen-6-ones

The functionalization of silica-coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) using chlorosulfonic acidwere afforded sulfonic acid-functionalized magnetic Fe3O4 nanoparticles (Fe3O4@SiO2–SO3H) that can be applied as anorganic–inorganic hybrid heterogeneous catalyst. An efficient and eco-friendly method for the one-pot synthesis of 7-alkyl-6H,7H-naphtho[1',2':5,6]pyrano[3,2 c]chromen-6-ones derivatives has been developed in the presence of Fe3O4@SiO2– SO3Hnanoparticles. The multi-component reactions of 4-hydroxycoumarin, β-naphthol and aromatic aldehydes were efficientlycatalyzed using novel nano-scale materials under solvent-free conditions. The present method offers several advantages suchas short reaction times, excellent yields, simple purification and facile catalyst separation.

Keywords:

multi-component reactions , nanoparticles , core-shell , Fe3O4@SiO2 –SO3H , chromen