Green Protocol for the Biginelli Three‐Component Reaction: Ag₃PW₁₂O₄₀ as a Novel, Water‐Tolerant Heteropolyacid for the Synthesis of 3,4‐Dihydropyrimidinones

Abstract

Biginelli three-component condensation of an aldehyde, β-keto ester, and urea proceeds smoothly on the surface of the silver salt of heteropolyacid (HPA), i.e. Ag 3 PW 12 O 40 , in water to afford the corresponding 3,4-dihydropyrimidinones in high-to-quantitative yields under mild conditions. The heterogeneous solid acid provides ease of separation of the catalyst and isolation of the products. The recovered catalyst can be recycled in subsequent reactions with consistent activity.

The Three‐Component Biginelli Reaction: A Combined Experimental and Theoretical Mechanistic Investigation

“…[2][3][4][5][6][7][8][9][10][11][12] Bignelli reactions can be performed under a variety of conditions, and several improvements of the experimental procedures have been reported in recent years. Although it has been traditionally catalyzed by strong Brønsted acids, Lewis acids such as LiClO 4 , LaCl 3 , InCl 3 , BiA C H T U N G T R E N N U N G (OTf) 3 , BiCl 3 , MnA C H T U N G T R E N N U N G (OAc) 3 , CuA C H T U N G T R E N N U N G (OTf) 2 , FeCl 3 , ZrCl 4 , or SnCl 2 [13][14][15][16][17] are now being increasingly used. The use of ionic liquids, [18][19][20] microwave irradiation, [7,[21][22][23][24][25][26][27][28][29][30][31] solid-phase reagents, [12,32,33] and polymer-supported catalysts have also been reported.…”

Heteropoly acids-catalyzed organic reactions in water: doubly green reactions

“…Most importantly, aromatic aldehydes carrying either electron-donating or -withdrawing substituents reacted well under the reaction conditions to give the corresponding dihydropyrimidinones in high-to-quantitative yields with high purity. This method was applicable to a wide range of substrates, including aromatic, aliphatic, α,β-unsaturated, and heterocyclic aldehydes, and provided a variety of biologically relevant dihydropyrimidinones in high to quantitative yields after short reaction times (103).…”

Polystyrene‐supported AICI3: A highly active and reusable heterogeneous catalyst for the one‐pot synthesis of dihydropyrimidinones

“…Recently, many synthetic methods for preparing dihydropyrimidinones have been reported including classical conditions, with microwave and ultrasound irradiation and by using Lewis acids as well as protic acid promoters such as: H 2 SO 4 [3] [7], heteropolyacids [8], BiCl 3 [9], Cu(OTf) 2 [10], TMSCl [11], LiClO 4 [12], LiBr [13], Ag 3 PW 12 O 40 [14], phenylpyruvic acid [15], FeCl 3 .6H 2 O/ HCl [16] and silica sulfuric acid [17]. Acidic ionic liquids as effective catalysts for this transfermation were also utilized [18].…”