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Abstract
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Fe 3 O 4 @SiO 2 @(CH 2 ) 3 -urea-quinoline sulfonic acid chloride, as a novel and efficient nanomagnetic cata- lyst bearing urea linkers, was designed, synthesized and then fully characterized by using various tech- niques. To investigate the catalytic activity of the described catalyst, it was used for the synthesis of coumarin containing 1,4-dihydropyridines (DHPs), through a condensation reaction of aromatic aldehy- des, 4-hydroxycoumarin, and ammonium acetate under solvent-free conditions. This procedure includes important aspects like simple procedure, simplicity of product isolation using water, decreasing the tem- perature of reaction, disuse of solvent, high to excellent yields, environmentally benign reaction condi- tions and short reaction times. Also, the presented catalyst was recycled and reused for at least five times with only a negligible decrease in its catalytic activity. The applied catalyst has both acidic and H-bond donor-acceptor sites so that it can use as a dual role catalytic system.
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