New three-component cyclocondensation reaction: microwave-assisted one-pot synthesis of 5-unsubstituted-3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions

Sixteen 5-unsubstituted-3,4-dihydropyrimidin-2(1H)-ones have been synthesized by microwave-assisted Biginelli reactions in a short and concise manner employing ZnI₂ as a catalyst under solvent-free conditions. All products were identified by IR, NMR, elemental analysis and HRMS. The advantages of this novel protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and expensive catalysts.     

1-Sulfopyridinium chloride:Green and expeditious ionic liquid for the one-pot synthesis of fused 3,4-dihydropyrimidin-2(1H)-ones and thiones under solvent-free conditions

1-Sulfopyridinium chloride portrayed as an efficient and recyclable ionic liquid for the synthesis of fused3,4-dihydropyrimidin-2(1H)-ones and thiones via a modified Biginelli reaction involving one-pot three component condensation of 6-methoxy-1-tetralone,arylaldehydes and urea/thiourea under solventfree conditions.Analytically pure products are formed within 10–20 min in excellent yields.     

邻甲基苯磺酸铜催化"一锅法"合成3,4-二氢嘧啶-2(1H)-酮

二氢嘧啶酮(DHPMs)及其衍生物具有广泛的生物活性,如抗病毒、抗肿瘤、抗癌、抗高血压及消炎等作用[1].此外,DHPMs及其衍生物作为钙通道阻滞剂、α1a-对抗剂和神经肽Y的对抗剂,显示出良好的药理活性[2].更重要的是,最近几种含二氢嘧啶酮-5-羧酸盐的海洋生物碱被成功分离出来,并表现出重要的生物学性质[3],某些可以阻止HIVgp-120-CD4键的形成,是一种潜在的HIV抑制剂[4].因此,对DHPMs及其衍生物的研究成为生物活性有机杂环化合物的研究热点之一.     

氯化镉催化三组分“一锅法”合成4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮的研究

在氯化镉催化作用下,以环己烷为溶剂,芳香醛、芳香酮和脲三组分"一锅法"合成了一系列4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮化合物。考察了溶剂和催化剂用量对产率的影响。通过IR、1H NMR、13C NMR和元素分析对产品结构进行了表征。该合成方法具有操作简单、反应时间短、反应条件温和,产率高等优点。     

TaBr5-catalyzed Biginelli reaction: one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones/thiones under solvent-free conditions

An efficient TaBr₅ (5-10 mol %)-catalyzed Biginelli reaction under solvent-free conditions for one-pot syntheses of 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their thione analogs is reported. The catalyst is stable at room temperature and employed under mild and environmentally friendly conditions.     

无溶剂条件下对甲基苯磺酸铝高效催化合成4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮

以芳香醛、芳香酮和尿素为原料,对甲基苯磺酸铝为催化剂,在90_oC、无溶剂条件下“一锅法”反应,高效合成了一系列4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮。产品结构通过IR,₁H NMR,₁₃C NMR和元素分析进行了表征。该方法具有操作简单、反应时间短、产率高、反应条件温和、不使用任何有机溶剂、催化剂廉价易得且可重复使用等优点,为标题化合物的合成提供了一种简便高效的绿色新途径。     

A Set of phenyl sulfonate metal coordination complexes triggered Biginelli reaction for the high efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions

Three new metal coordination complexes, namely, [Co ( DPE )(H₂O)₄]( DPE )( BS )₂ ( 1 ), [Co ( DPE )₂(H₂O)₄]( ABS )₂ ( 2 ), [Co ( DPE )(H₂O)₄]( MBS )₂(CH₃OH)₂ ( 3 ) [ DPE = (E)-1,2-di (pyridin-4-yl) ethene, BS = phenyl sulfonic acid, ABS = p-aminobenzene sulfonic acid, MBS = p-methylbenzene sulfonic acid] were obtained under hydrothermal conditions. Complexes 1 - 3 were structurally characterized by X-ray single-crystal diffraction, powder X-ray diffraction and IR. Complexes 1 and 3 exhibit a one-dimensional chain structure, and complex 2 does a zero-dimensional one. These three complexes further generate a three-dimensional supramolecular architecture via strong hydrogen bonding interactions and packing interactions. These three metal coordination complexes show high catalytic performance for green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones through the Biginelli reactions, which show several advantages such as excellent yields, short reaction times, eco-friendly synthesis conditions, and simple isolated workup procedure. Interestingly, the order of catalytic activities for these catalysts is the following: 3 > 1 > 2 , which can be ascribed to the acidities and hydrophobic interactions of phenyl sulfonate groups.     

Zinc perchlorate catalyzed one-pot synthesis of 3,4-dihydropyrimidinones under solvent-free conditions

Abstract

In this paper, we report zinc perchlorate hexahydrate [Zn(ClO₄)₂?6H₂O] as a highly effective catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. These improved reaction conditions allow the preparation of a wide variety of substituted dihydropyrimidinones in high yields and purity under mild reaction conditions. Compared with the classical Biginelli reaction, this method has the advantage of excellent yields and short reaction time in solvent-free conditions.     

A green synthesis of 3,4-dihydropyrimidin-2-ones and 1,5-benzodiazepines catalyzed by Sn(HPO4)2.H2O nanodisks under solvent-free condition at room temperature

Abstract

Heterogeneous Tin (IV) hydrogen phosphate nanodisks [Sn(HPO4)2.H2O] efficiently catalyzed the one-pot three component condensation of aromatic aldehydes, β-ketoesters and urea to produce 3,4–dihydropyrimidin-2-ones under solvent-free conditions at room temperature. Also, the catalyst is equally applicable for the preparation of 1,5–benzodiazepines under the same reaction conditions. The optimum load of the catalyst required is 10 mole% and reusable. Hence, the process is green.

微波辐射下浓硫酸催化嘧啶酮的无溶剂合成

微波辐射下,以浓硫酸为催化剂,芳香醛、尿素和乙酰乙酸乙酯为原料,无溶剂下发生B iginelli缩合反应,高产率地合成了10个3,4二-氢嘧啶-2酮-衍生物。该方法不仅反应条件温和,反应时间短,避免使用昂贵的催化剂,后处理过程简单,而且避免了使用溶剂给环境带来的污染,具有绿色合成的特点。     

Synthesis of 5-Cinnamoyl-3,4-dihydropyrimidine-2(1H)-ones

Two different approaches to the synthesis of 1-unsubstituted 5-cinnamoyl-3,4-dihydropyrimidine-2(1H)-ones have been developed. The first includes N(1)-protection of the starting 5-acetyl-3,4-dihydropyrimidine-2(1H)-one, further Claisen–Schmidt reaction, and cleavage of the protecting group. The second approach consists of one-pot condensation of urea, aldehyde, and cinnamoylacetone as dicarbonyl component. The 5-cinnamoylderivative synthesis starting from 5-acetyl-1,3-dialkyl-3,4-dihydropyrimidine-2(1H)-ones is also shown.     

A solvent-free reaction between acetophenone oximes and epoxy styrenes: an efficient synthesis of 2,4,6-triarylpyridines under neutral conditions

An efficient synthesis of 2,4,6-triarylpyridines is described which involves heating a mixture of an acetophenone oxime and an epoxy styrene under neutral, solvent-free conditions. Kröhnke pyridine products are obtained in excellent yields.     

Highly efficient and easy synthesis of 2,4,6-triarylpyridines catalyzed by pentafluorophenylammonium triflate(PFPAT) as a new recyclable solid acid catalyst in solvent-free conditions

Pentafluorophenylammonium triflate(PFPAT) was found to be a highly efficient catalyst for the preparation of 2,4,6- triarylpyridines from the reaction of acetophenone derivatives,aromatic aldehydes and ammonium acetate.Present methodology offers several advantages,such as short reaction time,high yields,simple procedure with an easy work-up and the absence of any volatile and hazardous organic solvent.In addition,this catalytic system can act as an active,inexpensive,metal-free,recoverable and recyclable catalyst.     

Cu(OTf)2: a reusable catalyst for high-yield synthesis of 3,4-dihydropyrimidin-2(1H)-ones

Copper(II) triflate catalyzes efficiently the three-component condensation reaction of an aldehyde, β-ketoester and urea in acetonitrile to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones in high yields. The catalyst exhibited remarkable reusable activity.     

1,3-Dibromo-5,5-dimethylhydantoin as a useful reagent for efficient synthesis of 3,4-dihydropyrimidin-2-(1<Emphasis Type="Italic">H</Emphasis>)-ones under solvent-free conditions

Efficient syntheses of 3,4-dihydropyrimidin-2-(1H)-ones and the corresponding thioxo derivatives using 1,3-dibromo-5,5-dimethylhydantoin (DBH) catalysis of a one-pot three-component Biginelli reaction of aldehydes, ethyl acetoacetate, and urea or thiourea under microwave irradiation are described. The advantages of this method are its short reaction times, high yields of the products, inexpensive and commercially available catalyst, and solvent-free conditions. Typical isolated yields exceed 70 % for arylaldehydes (9 examples) and aliphatic aldehydes (2 examples).     

An efficient bakers’ yeast catalyzed synthesis of 3,4-dihydropyrimidin-2-(1H)-ones

Bakers’ yeast (Saccharomyces cerevisiae) efficiently catalyzes the three-component Biginelli reaction of aldehydes, β-keto esters, and urea/thiourea to form 3,4-dihydropyrimidin-2-(1H)-ones in good to excellent yields.     

Synthesis of some new bis-3,4-dihydropyrimidin-2(1H)-ones by using silica-supported tin chloride and titanium tetrachloride

<正>Silica-supported tin chloride and titanium tetrachloride were prepared by the reaction of tin chloride and titanium tetrachloride with activated silica gel in refluxing toluene.These solid acids have been employed as the catalysts for the synthesis of bisdihydropyrimidin -2(1H)-ones from aromatic dialdehydes,1,3-dicarbonyl compounds and urea at 90℃under solvent-free conditions.     

Borax: An Ecofriendly and Efficient Catalyst for One-Pot Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones under Solvent-Free Conditions

Borax in the presence of a very small amount of 5 M sulfuric acid efficiently catalyses the three-component condensation of an aldehyde, β-ketoester, and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones or 3,4-dihydropyrimidin-2(1H)-thiones in good to excellent yields under solvent-free conditions at 80 °C. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yield, short reaction time (1–2 h), easy workup, and no use of volatile organic solvent.     

Regioselective dehydrogenation of 3,4-dihydropyrimidin-2(1H)-ones mediated by ceric ammonium nitrate

Ceric ammonium nitrate (CAN) has been explored for the regioselective oxidation of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs). Interestingly, we obtained ethyl 2,4-dioxo-6-phenyl-tetrahydropyrimidin-5-carboxylates as the major products during the oxidation of DHPMs by CAN/AcOH at 80 °C. The reaction afforded a mixture of products while employing CAN in organic solvents without additives. However, the regioselective dehydrogenated product, ethyl 6-methyl-4-aryl(alkyl)-pyrimidin-2(1H)-one-5-carboxylate was obtained by performing the reaction with NaHCO₃. The single crystal X-ray crystallography of ethyl 6-methyl-4-(2-phenyl)-pyrimidin-2(1H)-one-5-carboxylate revealed that the oxidized product existed in amidic form rather than aromatized enol form of pyrimidines. The efficiency of the present protocol enabled the synthesis of structurally diverse pyrimidines in moderate to good yields under milder reaction conditions.