L-Glutamine-Functionalized Magnetic Polystyrene for Highly Efficient Synthesis of 2- Amino-4H-Pyrans

In this study, we reported the synthesis and characterization of a novel magnetic polystyrene nanocatalyst functionalized with L-glutamine (L-Glu-MPS) and evaluation of its catalytic performance in a multicomponent organic reaction for the preparation of 2-amino-4 H -pyrans. The catalyst was prepared through magnetization of chloromethylated polystyrene (PS-Cl) using FeCl₂·4H₂O and FeCl₃·6H₂O, followed by covalent attachment of L-glutamine. The characteristics of the samples were meticulously analyzed by applying TGA, FT-IR, XRD, VSM, EDS mapping, SEM, and elemental analysis, confirming effective surface modification and satisfactory stability. The catalytic performance of L-Glu-MPS was examined in the three-component condensation reaction involving aromatic aldehydes, malononitrile, and ethyl acetoacetate, aimed at synthesizing 2-amino-4 H -pyran derivatives. The results demonstrated high efficiency of the nanocatalyst, providing excellent yields (88–98%) under mild, room-temperature conditions with short reaction times (25 min). Moreover, the catalyst demonstrated remarkable reusability, with at least 6 consecutive runs without significant loss in activity or structural integrity. These findings highlight L-Glu-MPS as a green, efficient, and reusable catalytic system for the sustainable synthesis of heterocyclic compounds.