Nanomagnetic 4-amino-3-hydroxynaphthalene-1-sulfonic as an efficient heterogeneous catalyst for multicomponent synthesis of 2-amino-3-cyano-4,6-diarylpyridines under green conditions.

Herein, we report the synthesis and application of a novel, magnetically retrievable sulfonic acid functionalized solid catalyst, prepared by immobilizing α-amino-3-hydroxynaphthalene-1-sulfonic acid onto alkyl halide-coated Fe3​O4​ magnetic nanoparticles. Comprehensive characterization confirmed its structure, morphology, and properties. Its catalytic efficacy was evaluated in the one-pot multicomponent cyclocondensation for polysubstituted pyridine derivatives, specifically 2-amino-3-cyano-4,6-diarylpyridines. This green and efficient protocol, utilizing aldehydes, ketones, malononitrile, and ammonium acetate in a water/ethanol mixture, achieved high yields, excellent functional group tolerance, and no byproduct formation. Furthermore, the catalyst exhibited remarkable reusability, remaining effective for at least five consecutive cycles through simple magnetic separation. This innovative catalyst provides a practical and efficient method for producing diverse heterocyclic compounds relevant to medicinal chemistry.