One-pot synthesis of dihydropyrimidones using silica-supported heteropoly acid as an efficient and reusable catalyst: Improved protocol conditions for the Biginelli reaction

Silica supported heteropolyacid catalyzed dehydration of aldoximes to nitriles and alcohols to alkenes

“…Supported HPA has proven to be the efficient catalysts for several organic transformations such as C-alkylation (25), esterification (26), Ritter reaction (27), Bigenelli reaction (28), and DakinÁWest reaction (29). Our group has also explored the catalytic activity of HPA for various other transformations (30,31).…”

Fe+3-montmorillonite K10: As an effective and reusable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and –thiones

“…In order to improve the efficiency of Biginelli reaction, a variety of catalysts have been reported which of them H 4 PMo 11 VO 40 [9], Dowex-50W [10], H 3 PW 12 O 40 /SiO 2 [11], MgBr 2 [12], polymer-supported 4-aminoformoyldiphenylammonium triflate [13], NaHSO 4 /SiO 2 [14], FeCl 3 [15], ZrCl 4 [16], Cu(OTf) 2 [17], Bi(OTf) 3 [18], yutterbium triflate [19], 12-molbdophosphoric acid [20], natural HEU type zeolite [21], Sr(OTf) 2 [22], covalently anchored sulfonic acid onto silica [23] [34] are examples.…”

Efficient catalytic synthesis of 2-imidazolines and bis-imidazolines with silica supported tungstosilicic acid

“…Some of the goals of using supported HPAs are the surface area enhancement, higher dispersion of acidic protons, heterogenization and acid strength control. These supported catalysts have been widely studied and found useful in many reactions such as the synthesis of 2,4-dihydropyrimidones, 12 metanethole , 13 α-aminonitriles 14 and esterification. 15,16 Imidazoline derivatives are of great interest and importance because of their pharmaceutical and synthetic material applications.…”