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《Catalysis communications》2007,8(3):279-284
Simple and improved conditions have been found to carry out the Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives. This synthesis was performed using 11-molybdo-1-vanadophosphoric acid (H4PMo11VO40) in ethanol solution. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yields (85–95%). 相似文献
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《Catalysis communications》2007,8(2):123-126
An efficient synthesis of dihydropyrimidinones from the aldehyde, 1,3-dicarbonyl compound and urea (thiourea) under solvent-free conditions, using fluoroboric acid as the catalyst, is described. Compared with the classical Biginelli reaction conditions, this new protocol has the advantage of high yields, short reaction time and simplicity in the experimental procedure. 相似文献
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Sunil R. Mistry Rikesh S. Joshi Suban K. Sahoo Kalpana C. Maheria 《Catalysis Letters》2011,141(10):1541-1547
Abstract
A series of dihydropyrimidin-2(1H)-one (DHPM) belongs to one of the important class of therapeutic and pharmacological active compound, were synthesized through the multicomponent reactions (MCRs) of aldehydes, ethyl acetoacetate and urea, followed by the heterogeneous catalyzed Biginelli reaction. In the present endeavour, medium (ZSM-5) and large pore zeolites (Y, BEA and MOR) as well as dealuminated zeolites BEA, were studied as catalysts. An excellent activity for DHPMs synthesis is achieved by optimizing accessibility of the reactants to the active sites and the surface polarity of zeolite catalysts. Moreover, the mechanism of Biginelli reaction was studied by means of GAUSSVIEW energy calculations of adsorbed acylimine intermediate on zeolite by using the density functional method (DFT). 相似文献5.
《Catalysis communications》2007,8(11):1641-1644
An efficient three-component synthesis of 3,4-dihydropyrimidinones using trichloroisocyanuric acid (TCCA) as a mild, homogeneous and neutral catalyst for Biginelli reaction in ethanol or DMF under reflux condition and microwave irradiation is described. Yields are excellent in either of the two conditions. 相似文献
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《Catalysis communications》2007,8(2):179-182
An improved protocol for the Biginelli reaction using CuI as a reusable catalyst is described. The synthesis of 3,4-dihydropyrimidin-2(1H)-ones was achieved in acetonitrile, water and under solvent-free condition. After separation of product from the reaction mixture, the mother liquor (acetonitrile or water) containing the catalyst was reused two times without any loss of activity. 相似文献
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Herein, we are reporting a facile route to synthesize magnetically separable Cu nanoparticle loaded CoFe2O4@SBA15 catalysts, which exhibits high catalytic activity towards (i) reduction of various synthetic dyes, trifluralin, (ii) synthesis of DHPMs via Biginelli reaction pathway in solventless condition and (iii) 1,2,3-triazole derivatives by ‘Click reaction’ in aqueous medium. To the best of our knowledge, this is the first time one single catalyst is reported which shows its high activity for these three important reactions. 相似文献
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An environmentally benign aqueous protocol for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones using Amberlyst-70 as a recyclable catalyst has been developed. The use of resinous, nontoxic, thermally stable and inexpensive Amberlyst-70, as a recyclable heterogeneous catalyst, makes the process simple with negligible chemical waste. Thus renders this method an environmentally acceptable synthetic tool for Biginelli reaction. 相似文献
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Sulfated tungstate catalyzed simple, one pot, solvent free and environmentally benign process for synthesis of dihydropyrimidinones via Biginelli reaction is described. It was found that the catalyst is reusable and exhibited remarkable activity. 相似文献
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3,4-二氢嘧啶酮衍生物具有重要生理活性,因此该类化合物的合成受到广泛关注。以廉价的三聚氯氰催化芳醛、尿素和乙酰乙酸乙酯或环戊酮的“一锅法”Biginelli反应,在无溶剂和无保护的条件下合成了一系列芳亚甲基稠环嘧啶酮化合物,其中代表性化合物结构经NMR、IR和熔点等表征手段确定。该方法所用催化剂经济易得,且催化剂用量较少,反应条件温和,产率较高,为3,4-二氢嘧啶-2(1H)-酮衍生物的合成提供了新的方法。 相似文献
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While chemical efficiency relies on several factors, the multicomponent reaction (MCR) approach was considered as a powerful synthetic tool for preparing target molecules of biological relevance in an efficient manner. Four classes of new bioactive molecules were designed and synthesized by asymmetric MCRs, in some cases with the cooperation of polymer-assisted solution-phase (PASP) technique. These include (a) C-glycosyl dihydropyrimidines and dihydropyridines via Biginelli and Hantzsch cyclocondensations, (b) C-glycosyl beta-amino acids via Mannich- and Reformatsky-type reactions, (c) C-glycosyl beta-lactams via Staudinger reaction, and (d) heterocyclic alpha-amino acids (glycine and alanine) via the Biginelli and Hantzsch reactions. 相似文献
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Solid acids comprising 12-tungstophosphoric acid and 12-tungstosilicic acid anchored on to metal oxide (ZrO2), zeolites (Hβ and HZSM-5), and mesoporous material (MCM-41) were synthesized, characterized and used as the catalysts. A solvent free green route to carry out the Biginelli cyclocondensation reaction is described over synthesized catalysts. The method provides an efficient and much improved protocol of Biginelli reaction in terms of solvent free conditions, high yields up to 98 %, very short reaction time of 15 min, and simple work-up procedure. Based on the above study a best catalyst among all is proposed and is recycled up to four times without any significant change in % yields of the product. Another important feature of this method is survival of a variety of functional groups under the reaction conditions. 相似文献
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Córdova MO Flores Ramírez CI Bejarano BV Arroyo Razo GA Pérez Flores FJ Tellez VC Ruvalcaba RM 《International journal of molecular sciences》2011,12(12):8575-8580
In this work, the results of a study comparing the use of irradiation from different regions of the infrared spectrum for the promotion of several organic reactions, are presented and discussed. This use of eco-conditions provides a green approach to chemical synthesis. A set of ten different organic reactions were evaluated, including the Knoevenagel, Hantzsch, Biginelli and Meldrum reactions. It is important to highlight the use of a commercial device that produces infrared irradiation in the near infrared region and its distribution by convection providing heating uniformity, significantly reducing reaction times, achieving good yields and proceeding in the absence of solvent. It is also worth noting that a variety of different reactions may be performed at the same time. Finally, the products obtained were identified using TLC, together with corresponding MS-data, complementarily in comparison of NMR (1)H and (13)C data with literature information. 相似文献
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苯甲醛、尿素和乙酰乙酸乙酯三组分“一锅煮”可以同时制备Biginelli和Hantzsch两种产物。教学中通过改变催化剂种类、反应物料比、反应溶剂等条件,引导学生探讨反应条件的改变对总产率及两种异构体比例的影响。实验中通过薄层色谱来跟踪反应进程,通过柱色谱分离混合物,最后通过熔点、红外光谱对合成的化合物进行结构表征。本实验集无机化学、有机化学、基础分析化学和仪器分析于一体,具有很强的实用性和可操作性,可作为有机化学实验中的综合性、设计性实验开设。 相似文献
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《Catalysis communications》2003,4(9):449-453
Among the Si-MCM-41 or montmorillonite K 10 clay supported ZnCl2, AlCl3, GaCl3, InCl3 and FeCl3 catalysts, FeCl3/Si-MCM-41 shows best performance for the microwave-assisted synthesis of dihydropyrimidinones by the Biginelli reaction involving multicomponent condensation of aromatic aldehyde, ethyl acetoacetate and urea in the absence of any solvent. It is a promising catalyst for the microwave-assisted reaction providing high product yield in a short period (3.0–5.0 min). 相似文献
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Urease is a superior biocompatible catalyst for switching from the Biginelli reaction to urea-based synthesis of 1,4-dihydropyridines in water, where 100% switching occurs at 0.02 g/mL of enzyme. Hantzsch reaction with ammonium acetate (NH4OAc) is inefficiently catalyzed by urease (70%, 4 h), and heavy metal ions inhibit the urease-catalyzed reactions with urea or NH4OAc. Promotion of the urea-based Hantzsch reaction by urease and its inhibition with Hg2 + supports specificity of urease for in situ generation of ammonia, whereas the role of urease in further transformations is not so specific. The features of this enzymatic method are reusability, mild reaction conditions, biocompatibility, generality, and high yield of products. 相似文献