Nanometasilica disulfuric acid (NMSDSA) and nanometasilica monosulfuric acid sodium salt (NMSMSA) as two novel nanostructured catalysts: applications in the synthesis of Biginelli-type, polyhydroquinoline and 2,3-dihydroquinazolin-4(1H)-one derivatives

Nanometasilica disulfuric acid (NMSDSA) and nanometasilica monosulfuric acid sodium salt (NMSMSA) as two nanostructured novel, green and heterogeneous catalysts were designed, synthesized and fully characterized by FT-IR, energy-dispersive X-ray spectroscopy, X-ray diffraction patterns, scanning electron microscopy, transmission electron microscopy and thermal gravimetric analysis. Then their catalytic applications were studied in the Biginelli-type reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives via one-pot three-component condensation reaction between several aldehydes, ethyl acetoacetate and urea or thiourea. To further study catalytic properties of NMSDSA and NMSMSA, they were used in the synthesis of polyhydroquinoline and 2,3-dihydroquinazolin-4(1H)-one derivatives under same reaction conditions. NMSDSA and NMSMSA have advantages such as cost-effectiveness, cleaner reaction profile, benign and heterogeneous characters, reusability of the catalysts and being in agreement with the green chemistry protocols. The described nanostructured catalysts have natural-based acids and potential for industrial production.