An ‘on-water’, efficient, high yielding, expeditious method has been developed for the synthesis of 1,4-
dihydropyridine (1,4-DHP) derivatives via an one-pot multi-component condensation of dimedone or
4-hydroxycoumarine, aldehydes, and ammonium acetate using Fe3O4@SiO2 nanoparticles as a recyclable
heterogeneous catalyst. This method takes advantage of the fact that water, a green solvent is used in
combination with Fe3O4@SiO2 nanoparticles as catalyst which can be easily recovered magnetically
and reused for further runs.