Anchoring cobalt nanoparticles on to the grafted mono(6-ethylene-diamino-6-deoxy)-β-cyclodextrin to magnetic chitosan for enhanced catalytic performance of the synthesis of pyrano[2,3-c]pyrazole-3-carboxylates

A novel magnetic nanocatalyst based on nickel ferrite coated with chitosan and ethylenediamine-functionalized β-cyclodextrin and decorated with cobalt nanoparticles (NiFe 2 O 4 @Cs-CDEDA@Co) was developed for the efficient green synthesis of heterocycles. This bifunctional catalyst provided Lewis acidic and basic sites, enabling sequential Knoevenagel condensation, Knorr-type cyclization, and Michael addition. Under mild aqueous conditions (H₂O/EtOH, 50 °C), twenty-eight derivatives of dihydropyrano[2,3-c]pyrazole and pyranopyrazolopyrimidine were synthesized in excellent yields in a short time. The catalyst demonstrated excellent stability (confirmed by XRD), negligible metal leaching (ICP), and reusability over six cycles without performance loss. Structural characterization (FTIR, XRD, SEM, TEM, TGA, VSM, EDX) confirmed homogeneous morphology and nanoscale particle sizes (40–50 nm). These findings highlight the potential of this nanocatalyst platform for sustainable and scalable multicomponent reactions under environmentally benign conditions.