Efficient Synthesis of Dihydropyrimidines Using a Highly Ordered Mesoporous Functionalized Pyridinium Organosilica

Abstract

A Brönsted acidic ionic solid pyridinium-functionalized organosilica network (PMO-Py-IL) was demonstrated to efficiently catalyse one-pot Biginelli condensation reaction. The green synthesis of 3,4-dihydro-2(H)-pyrimidinones (DHPMs) with high yield was carried out via one-pot three component condensation of β- dicarbonyls, aldehydes, and urea in the presence of a catalytic amount of PMO-Py-IL nanomaterial as an efficient nanocatalyst under solvent free conditions. Furthermore, the catalyst showed outstanding stability and could be easily separated and reused for at least ten reaction runs without significant loss of activity and product selectivity. The green protocol features simple set-up, cost-effectiveness, easy work-up, eco-friendly and mild reaction conditions.

The Synthesis of Nitrogen- and Oxygen-Containing Heterocyclic Scaffolds Assisted by Ionic Liquids: A 2022 Literature Survey

“…The catalytic activity of novel caffeine-based Bronsted acidic ionic liquids (CaffBAIL) was reported by Ezabadi and co-workers for the of dihydropyrimidinones (174, Scheme 59)under solvent free conditions from ethyl acetoacetate (173), urea (112) and substituted benzaldehyde (1) in 77-94% yields. 128 The white coloured powdered ILs, CaffBAIL was synthesized from caffeine and 1,4-butane sultone and This article is protected by copyright.…”

“…Li and co-workers synthesized cyclic carbonates (114) via alcoholysis of urea (112) using eco-friendly, Lewis acid imidazolium-based 1-methyl-3-octyl-1H-imidazol-3-ium chloride having moderate side chain (Scheme 35). 94 They have synthesized different final ILs with variable alkyl by the treatment of previously prepared ILs with ZnCl 2 or metal chloride in different molar ratio and screened them for the catalytic activity for the synthesis of 114 from urea (112) and 1,2-diols (113).Further, they could also achieve the recycling of ILs through vacuum distillation with the 20% loss of yields afterwards fourteenth consecutive run. The anionic and cationic counterparts of ILs could perform the amphiphilic dual activation to fetch112 and 113 in close proximity with each other to form hydroxyethyl carbamate, which underwent ILs promoted intramolecular cyclization to yield 114 in 97-38% yields.…”

“…Imidazolium based ILs catalysed synthesis of cyclic carbonates (114) using urea (112) and 1,2-diols (113).…”

“…The synthesis of 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) via the Biginelli multicomponent reactions of aldehyde (137), urea (112), and β-keto ester (138) was carried out by Singh and his colleagues as described in Scheme 45. 105 In the presence of adamantyl-(L)-prolinamide as a catalyst and p-toluene sulfonic acid (p-TSA) as an additive, the reaction yielded 16-74% of the desired product with 7-82% enantioselectivity.…”

“…Rajabi et al have recently reported the use of pyridinium-functionalized organosilica networks (PMO-Py-IL) using Brønsted acidic ILs to catalyze the one-pot Biginelli condensation for the synthesis of 3,4-dihydro-2(H)-pyrimidinones (158, Scheme 52). 112 The pyridinium based ILs catalyzed three component condensation of β-dicarbonyls (155), aromatic aldehydes (87), and urea (112) to yield 156 at 50 o C for 15 min under solvent free conditions. The pyridinium based IL was obtained by the treatment of diethyl pyridine 2,6dicarboxylate with APTES followed by loading of pluronic acid (P123) and trifluoroacetic acid.…”