Silver, iron, and nickel immobilized on hydroxyapatite-core-shell gamma-Fe2O3 MNPs catalyzed one-pot five-component reactions for the synthesis of tetrahydropyridines by tandem condensation of amines, aldehydes, and methyl acetoacetate

In this study, Ag, Ni2+, and Fe2+ immobilized on hydroxyapatite-core-shell -Fe2O3 nanoparticles (-Fe2O3@HAp-Ag, -Fe2O3@HAp-Ni2+, and -Fe2O3@HAp-Fe2+) as a new and reusable Lewis acid magnetic nanocatalyst was successfully synthesized and reported for an atom economic, extremely facile, and environmentally benign procedure for the synthesis of highly functionalized tetrahydropyridines derivatives 4a-t is described by one-pot five-component reaction of 2 equiv of aldehydes 1, 2 equiv of amines 2, and 1 equiv of methyl acetoacetate 3 in EtOH at room temperature in good to high yields and short reaction time. The presented methodology offers several advantages such as easy work-up procedure, reusability of the magnetic nanocatalyst, operational simplicity, green synthesis avoiding toxic reagents and solvent, mild reaction conditions, and no tedious column chromatographic separation.