Eco-friendly and efficient synthesis of 1,4-dihydropyridines using a recyclable l-arginine-modified magnetic natural phosphate nanocatalyst

A magnetic natural phosphate functionalized with arginine (MNP‑Arg) was synthesized and fully characterized using FTIR, XRD, XRF, SEM/EDS, VSM, and elemental analysis, which confirmed the successful functionalization and magnetic behavior of the synthesized catalyst. MNP‑Arg efficiently catalyzed the synthesis of 1,4‑dihydropyridines (1,4‑DHPs) in ethanol at room temperature under mild conditions, affording diverse products in 86–98% yield within 10–20 min using only 20 mg of catalyst. The catalyst was readily recoverable by magnetic separation and maintained activity for nine consecutive cycles, demonstrating high efficiency, recyclability, and improved environmental compatibility.