A green synthesis of dihydropyrimidinones by Biginelli reaction over Nafion-H catalyst

A Nation-H catalyzed, single step and environmentally friendly process for synthesis of dihydropyrimidinones is described. This adopted protocol for Biginelli reaction has the advantages of reusability of the catalyst, high yields and ease of separation of pure products.

An efficient Biginelli one-pot synthesis of new benzoxazole-substituted dihydropyrimidinones and thiones catalysed by trifluoro acetic acid under solvent-free conditions

An efficient synthesis of benzoxazole-substituted 3,4-dihydropyrimidinones （DHPMs） using trifluoro acetic acid as the catalyst for the first time from an aldehyde, 13-keto ester and benzoxazole-substituted urea/thiourea under solvent-free conditions is described. Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of excellent yields （80-91%） and short reaction time （40-130 min） at reflux temperature. 2009 M. Adharvana Chad. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Synthesis of 4-Aryl-3,4-dihydropyrimidinones Using Microwave-assisted Solventless Biginelli Reaction

4-Aryl-3, 4-dihydropyrimidinones were synthesized using microwave-assisted,solvent-free protocol of the Biginelli reaction. The simple method provides the title compounds in78%―95% yields by the reaction of aromatic aldehydes with ethyl acetoac-etate and urea/thiourea inthe presence of a catalytic amount of cone. HCl. Lewis acids, such as ZnCl_2, SnCl_2, FeCl_3·6H_2O,and CuCl_2·2H_2O, were also found to be efficient catalysts for the synthesis ofdihydropyrimidinones.

Diketene-based neat four-component synthesis of the dihydropyrimidinones and dihydropyridine backbones using silica sulfuric acid(SSA)

Heterocyclic skeleton building blocks to afford dihydropyrimidinones and dihydropyridines based on neat adducts of diketene, alcohols and aldehydes via silica sulfuric acid （SSA） catalyzed ring opening of diketene in four-component Biginelli-type and Hantzsch-type reactions are presented.

无溶剂条件下用于合成3,4-二氢嘧啶-2(1H)-酮的高效、可磁性回收Fe_3O_4纳米粒子催化剂(英文)

The catalytic activity of Fe3O4 nanoparticles (NPs) in a one-pot three component condensation reaction consisting of an aromatic aldehyde, urea or thiourea, and a β-dicarbonyl under solvent-free conditions was investigated. This reaction affords the corresponding dihydropyrimidinones (thiones) in high to excellent yields. Compared with the classical Biginelli reactions this method consistently gives a high yield, easy magnetic separation, a short reaction time, and catalyst reusability.

Indium (III) Tribromide : An Excellent Catalyst for Biginelli Reaction

A highly efficient catalyst indium (III) tribromide is used to synthesize 5-alkoxy-carbonyl-4-hydrocarbyl-3,4-dihydropyrimidin-2(1H)-ones by a three-component coupling of beta-keto ester, aldehydes and urea through improved Biginelli reaction.

一个简单、环境友好的硅胶固载硫酸催化Biginelli反应体系(英文)

A protocol for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and-thiones was developed by means of a three-component condensation of an aldehyde,a β-dicarbonyl compound,and urea or thiourea in acetic acid catalyzed by silica-bonded S-sulfonic acid.Compared to the classical Biginelli reaction conditions,this new protocol has the advantages of consistently excellent yields and short reaction times.After the reaction,the catalyst could be recovered easily and reused with little change in its activity.

Pineapple Juice as a Natural Catalyst: An Excellent Catalyst for Biginelli Reaction

An efficient and greener synthesis of a series of dihydropyrimidinone (DHPMs) derivatives were accomplished via three-component one-pot cyclocondensation between substituted aryl aldehydes, diketone/ke- toester and urea. This solvent free approach is totally nonpolluting having several advantages such as shorter reaction time, mild reaction conditions, simple workup and reduced environmental impact.

One-pot Synthesis and Characterization of 13-Acetyl-9-methyl-11-oxo-8- oxa- 10,12-d iazatricyclo [7.3.1.0^2,7] trideca- 2,4,6- triene

An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-ll-oxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Biginelli condensation and intramolecular Michael-addition by using magnesium bromide as an inexpensive and easily available catalyst in a solvent-free condition is described. The structural elucidation of the product is reported by ^1H- and ^13C NMR spectra. The product can also be identified by its EI TOF mass spectrometry based on the molecular ion at m/s 246（10%） and on the fragment ions in which two nitrogen atoms are remained. Three kinds of characteristic fragmentation pathways from the molecular ion were observed. One is the loss of the OH radical to form the dihydropyrimidinone cation at m/z 229（48%）, followed by elimination of a molecular methane forming the pyrimidinone cation at m/z 213（27%）. The second is the cleavage of the C6H4OH radical, and the formation of the dihydropyrimidinone cation at m/z 153（24%）. The third one is the loss of MeC-O radical to afford the oxygen-bridged fragment ion at m/z 203（33%）.

Oxidation of 3,4-dihydropyrimidin-2(1H)-ones with nitrosonium(NO^+)

3,4-Dihydropyrimidin-2（1H）-ones （DHPMs） were oxidized with 1.2 equiv, of nitrosonium tetrafluoroborate （NO^＋BF4^-） to pyrimidin-2（1H）-ones in acetonitrile at room temperature in high yields.

Synthesis and pharmacological activity evaluation of curcumin derivatives

Curcumin 3,4-dihydropyrimidinones/thiones/imines have been synthesized using one-pot cyclocondensation of curcumin with substituted aromatic aldehydes and urea/thiourea/guanidine in the presence of chitosamine hydrochloride as a biodegradable and nontoxic catalyst under solvent-free microwave irradiation.The synthesized product was purified by crystallization from ethanol and the process does not involve any hazardous solvent.All the synthesized curcumin derivatives 4a-o were screened for antioxidant and anti-inflammatory activity.Biological activity data of the synthesized showed that most of the synthesized compounds exhibited greater antioxidant and anti-inflammatory activity than curcumin.

One-pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-one Using TsOH as a Catalyst under Microwave Irradiation

A series of Biginelli compounds was synthesized using TsOH as a catalyst under microwave irradiation. This simple method provided the title compounds in 86%-98% yields by the reaction of aromatic aldehydes with 1,3 carbonyl compound and urea. The structure of 4o was determined by single crystal X ray diffraction analysis.