OICC Press Iranian Journal of Catalysis 2345-4865 15 3 2025 09 30 Fe3O4@3-Aminopropyltriethoxysilane-SO3H: A greener catalyst for one-pot synthesis of pyranopyrimidine derivatives 10.57647/j.ijc.2025.1503.37 EN Raju Shekhanavar Department of Chemistry, Rani Channamma University, Belagavi, P-B, NH-4-591156, India Aravind Kamath Department of Chemistry, Rani Channamma University, Belagavi, P-B, NH-4-591156, India Kantharaju Kamanna Department of Chemistry, Rani Channamma University, Belagavi, P-B, NH-4-591156, India Journal Article 2025 09 30 The present work describes the eco-friendly preparation of magnetic nanoparticles Fe3O4 (MNPs) using Water Extract of Lemon Fruit Shell Ash (WELFSA) as a greener agro-waste solvent medium and further functionalized with 3-aminopropyltriethoxysilane and -SO3H. The prepared heterogeneous Lewis acid was explored for one-pot synthesis of pyrano[2,3-d] pyrimidine derivatives using aromatic aldehyde, ethyl cyanoacetate, and barbituric or thiobarbituric acid, accelerated by microwave irradiation in ethanol as a co-solvent. The reaction is optimized by various methods such as magnetic stirring, ultrasound, mechanochemical, and microwave irradiation, but the microwave irradiation method gives excellent product isolation with a faster rate and a high yield of 82-92% with high purity. The advantages of the present approach are chemical-free, no hazardous solvents, and considered as an eco-friendly protocol for the synthesis of pyrano [2,3-d] pyrimidine derivatives. The final product isolated is recrystallized in ethanol and characterized by FT-IR, 1H-, 13C-NMR, and LC-MS spectrometry. Further, some of the selected pyrano [2, 3-d] pyrimidine derivatives (4a, 4d, 4f, 4m, 4o, and 4r) are subjected to anti-microbial activity studies. The tested derivatives show anti-microbial activity comparable to the activities of reference antimicrobials. Highlights Greener synthesis of Fe3O4 demonstrated Further surface modification to Fe3O4@APTES-SO3H, an acid functionality attached, and characterized using various techniques The application of this prepared catalysts demonstrated for pyranopyrimidine derivatives synthesis.  The present approach highlighted rapid, simple, avoid use of chromatographic purification, inexpensive, recyclable catalyst, and a green synthetic protocol Some of the selected derivatives screened for (4a, 4d, 4f, 4m, 4o and 4r) antimicrobial activity studies, and derivatives showed comparable activities.