Phosphotungstic acid grafted zeolite imidazolate framework as an effective heterogeneous nanocatalyst for the one‐pot solvent‐free synthesis of 3,4‐dihydropyrimidinones

Phosphotungstic acid (H₃PW₁₂O₄₀, PTA) supported on ZIF‐9(NH₂) was synthesized for the first time and performed as an effective and environmental friendly catalyst in the one‐pot three component Biginelli condensation of different substituted benzaldehydes with ethyl acetoacetate and urea to afford the corresponding 3,4‐dihydropyrimidin‐2‐(1H)‐ones under solvent‐free conditions. ZIF‐9(NH₂) and the prepared nanocatalyst PTA@ZIF‐9(NH₂) were characterized by XRD, FESEM, TEM, EDX, BET, AAS, TGA, UV–Vis, and FT‐IR. After reaction, the nanocatalyst can be easily separated from the reaction mixture by centrifuge and the recovered catalyst can be reused for at least five times with a 14% reduction in yield after the fifth run. This study showed that ZIF‐9(NH₂) can be utilized as a promising support for PTA and developed a highly active, stable and reusable heterogeneous catalyst under easy reaction condition in the multi‐component organic synthesis.