Fe3O4@SiO2-SO3H as a recyclable heterogeneous nanomagnetic catalyst for the one-pot synthesis of substituted quinolines via Friedländer heteroannulation under solvent-free conditions

An efficient method has been developed for the Friedländer synthesis of substituted quinolines through a condensation reaction of 2-aminoaryl ketones with α-methylene ketones in the presence of a catalytic amount of nano Fe3O4@SiO2-SO3H under solvent-free conditions at 110 °C. The reactions are completed in short times, and the products are obtained in good to excellent yields. The results revealed several advantages to our procedure, including high product yields, short reaction time, facile work-up procedure, simplicity in operation, eco-friendly reaction conditions, reusability of the catalyst and green aspects by avoiding toxic catalysts and solvents. The catalyst could simply be separated and recovered from the reaction mixture by an external magnet and reused in subsequent reactions without significant loss in activity.