Friedländer Synthesis of Substituted Quinolines Using an Efficient and Reusable Brønsted Acid Ionic Liquid Supported on Fe3O4@SiO2 Nanoparticles under Solvent-free Conditions

In this study, a highly efficient and recyclable Brønsted acid ionic liquid, 1-methyl-3-(3-triethoxysilylpropyl)-1H-imidazol-3-ium hydrogensulfate, immobilized on the surface of Fe3O4@SiO2 (MNP-IL-HSO4) was prepared and characterized. Then, the catalytic activity of this nanomagnetic catalyst was investigated in the Friedländer synthesis of substituted quinolines through the cyclocondensation reaction of o-aminoaryl ketones with α-methylene carbonyl compounds under solvent-free conditions. The present protocol has several advantages, including short reaction times, high yield of products, simplicity in operation, simple work-up and reusability of the catalyst.