Investigation of the interaction of ethyl acetoacetate with nano alumina particle as Lewis acid in acetonitrile solvent

The enol form of ethyl acetoacetate (EAA) displays interesting spectroscopic characteristics; this form of ethyl acetylacetate is very important in condensation reaction. In this investigation, we have studied the interactions and the complex formation constants (K _f) with nano alumina (10?C20 nm) particle and alumina (mesh 135) compounds as Lewis acids in the acetonitrile solvent using absorption spectroscopy and related calculations. Furthermore, in this study we calculated the thermodynamic parameters of this reaction. The trend of reactivity of the ethyl acetoacetate (EAA) complexes toward the above Lewis acids, based on the solvent as follows: nano alumina compound > alumina compound.     

Mn(III)acetate-mediated additions of active methylene compounds to bicyclic olefins: Synthesis of bicyclic olefin-fused dihydrofurans

Bicyclic alkenes such as benzonorbornadiene, oxabenzonorbornadiene, norbornene, and norbornadiene were reacted with 1,3-cyclohexanedione and ethyl acetoacetate in the presence of Mn(OAc)₃ and Cu(OAc)₂. Except for the reaction of benzonorbornadiene and ethyl acetoacetate, dihydrofuran derivatives were the only products obtained. The formation of naphthalene derivatives was observed together with dihydrofuran in the aforementioned benzonorbornadiene/ethyl acetoacetate reaction. Additionally, the dihydrofuran product from the addition of ethyl acetoacetate to norbornadiene was slowly converted into epoxide derivative with air. The mechanism for the formation of the products is discussed.     

高效液相色谱法分析乙酰乙酸乙酯制备脱氢乙酸反应液中的脱氢乙酸和乙酰乙酸乙酯

乙酰乙酸乙酯经Claisen缩合反应得到脱氢乙酸是目前工业生产脱氢乙酸的一种主要方法。由于乙酰乙酸乙酯存在酮-烯醇式互变异构体,采用高效液相色谱分析时,存在吸光值和最大吸收波长的差异问题,并且容易引起色谱峰分裂和拖尾。通过优化色谱条件,将烯醇式乙酰乙酸乙酯转化为酮式异构体,避开烯醇式异构体的干扰,使乙酰乙酸乙酯的峰形更好,定量更准确,从而以酮式乙酰乙酸乙酯的定性、定量分析替代乙酰乙酸乙酯的定性、定量分析,进而建立一种同时检测乙酰乙酸乙酯法制备脱氢乙酸反应液中脱氢乙酸和乙酰乙酸乙酯的高效液相色谱法。采用Agilent HC-C₁₈色谱柱(250 mm×4.6 mm, 5 μm)分离,紫外检测波长为290 nm,柱温为35 ℃,流动相为甲醇-0.3%醋酸铵缓冲溶液(5:95, v/v,醋酸调节pH 6.0),流速为0.6 mL/min。在线性范围内,脱氢乙酸和乙酰乙酸乙酯的线性相关系数分别为0.99995和0.99992;加标回收率分别为98.5%和101.3%;相对标准偏差均小于1.0%。该方法具有较好的准确性和灵敏度,可简便、快速地同时对反应液中的脱氢乙酸和乙酰乙酸乙酯进行定性、定量分析,从而为乙酰乙酸乙酯法制备脱氢乙酸反应进程的控制提供参考。     

Tracing of ethyl 2-acetyl-3-(arylamino)butanoate intermediates (β-amino ketones) and their structural confinement

Tracing of ethyl 2-acetyl-3-(phenylamino)butanoate intermediates (β-amino ketones) was performed during the course of N-arylpiperidone synthesis by reaction of aromatic amines, acetaldehyde, and ethyl acetoacetate. The structural confinement and stereochemistry of these molecules were explained by use of 2D NMR spectroscopy and X-ray crystallography.     

Formation,structure and heterocyclization of aminoguanidine and ethyl acetoacetate condensation products

Condensation of aminoguanidine hydrochloride and ethyl acetoacetate results in 2,3-diamino-6-methylpyrimidin-4(3H)-one, 5-hydroxy-1-carboxamidino-3-methylpyrazole or ethyl N-[(5-hydroxy-3-methylpyrazol-1-yl)imidoyl]aminocrotonoate depending on the type of the base. Formation of pyrazole derivatives occurs in the case of dequaternized substrate imine-group protonating by the acids formed as a result of ion exchange reaction. Chelate fragment of amidinohydroxypyrazole structure provides stabilization of this compound and stipulates its inertness towared the heterocycle closure.     

Studies on the Biginelli Reactions of Salicylaldehyde and 2‐Hydroxy‐l‐naphthaldehyde

The Biginelli reactions of salicylaldehyde and 2‐hydroxy‐l‐naphthaldehyde with ethyl or methyl acetoacetate, ethyl benzoylacetate, and urea have been reinvestigated both in the structures of the reaction products and in the reaction conditions. Salicylaldehyde with ethyl and methyl acetoacetate resulted in oxygen‐bridged tricyclic tetrahydro pyrimidines, whereas with ethyl benzoylacetate afforded the only normal 3,4‐dihydropyrimidin‐2‐one. 2‐Hydroxy‐l‐naphthaldehyde with ethyl and methyl acetoacetate formed the tricyclic compounds. Steric effect is likely to be the principal determinant in governing the formation of product dichotomy. Previous controversial results as to the structure of the Biginelli products have been discussed and settled. The molecular structures of the dihydropyrimidinones and bridged tricyclic products have been fully characterized and confirmed unambiguously by single crystal X‐ray diffraction.     

Electrochemically induced one pot synthesis of 1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile derivatives via a four component-tandem strategy

An efficient one pot, multicomponent-tandem synthesis of highly functionalized 1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile is reported by electrochemically induced condensation of ethyl acetoacetate, hydrazine hydrate, malononitrile and various aromatic aldehydes. The reaction is carried out in an undivided cell, at a constant current in the presence of NaBr as a supporting electrolyte and ethanol as solvent.     

First catalyst- and solvent-free synthesis of 3,4-dihydropyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones and -thiones

A completely green and environmentally benign Biginelli synthesis of 3,4-dihydropyrimidine-2(1H)-ones and -thiones by one-pot three-component reaction of aromatic aldehydes with ethyl acetoacetate and urea or thiourea without any catalyst under solvent-free conditions is described.     

Efficient atom-economic one-pot multicomponent synthesis of benzylpyrazolyl coumarins and novel pyrano[2,3-c]pyrazoles catalysed by 2-aminoethanesulfonic acid (taurine) as a bio-organic catalyst

The present work describes eco-friendly multicomponent protocol for the synthesis in excellent yields of structurally diverse benzylpyrazolyl coumarin 5 (a–s) involving the reaction of 4-hydroxycoumarin, ethyl acetoacetate, hydrazine hydrate/phenyl hydrazine hydrate and aldehydes, also novel pyrano[2,3-c]pyrazole derivatives 8 (a–k) integrated by isonicotinic acid hydrazide from reaction of aldehyde, ethyl acetoacetate, malononitrile with isoniazid, employing water as a reaction medium and 2-aminoethanesulfonic acid (taurine) as the catalyst. This new methodology endowed the advantages such as short reaction time, recovery of catalysts after catalytic reaction and reusing them without losing their activity and alleviate of operation.     

A green one-pot multicomponent synthesis of 4H-pyrans and polysubstituted aniline derivatives of biological, pharmacological, and optical applications using silica nanoparticles as reusable catalyst

A one-pot practical, efficient, and environmentally benign multicomponent synthesis of 4H-pyrans and polysubstituted aniline derivatives of biological, pharmacological, and optical applications has been developed using a very mild, neutral, and reusable silica nanoparticles as catalyst. The 4H-pyran derivatives were synthesized by a three component reaction of an aldehyde, malononitrile, and 5,5-dimethyl-1,3-cyclohexanedione or ethyl acetoacetate at room temperature or refluxing in ethanol. Alternatively, polysubstituted anilines were synthesized via a four component reaction of an aldehyde, a ketone, and two equivalents of malononitrile in ethanol.     

A new,convenient and expeditious synthesis of 4-alkyl-5-methyl-1H-pyrazol-3-ols in water through a multicomponent reaction

A new, simple and efficient synthesis of 4-alkyl-5-methyl-1H-pyrazol-3-ols in water by a two-pot four component reaction of ethyl acetoacetate, hydrazine hydrate, aldehyde and ketone in presence K₂CO₃ as the catalyst is described. Use of water as the reaction medium, operational simplicity, mild reaction conditions, application of a cost-effective, nontoxic and easily available catalyst with auto-tandem catalysis, wide substrate scope, easy workup and purification process make the protocol highly attractive.     

One-pot three-component reaction of 3-(polyfluoroacyl)chromones with active methylene compounds and ammonium acetate: regioselective synthesis of novel R-containing nicotinic acid derivatives

Reactions of 3-(polyfluoroacyl)chromones with acetoacetamide and ethyl acetoacetate in the presence of ammonium acetate proceed at the C-2 atom of the chromone system with pyrone ring-opening and subsequent cyclization to 5-salicyloyl-2-methyl-6-(trifluoromethyl)nicotinamides, ethyl 5-salicyloyl-2-methyl-6-(trifluoromethyl)nicotinates, and ethyl 5-hydroxy-2-methyl-5-(polyfluoroalkyl)-5H-chromeno[4,3-b]pyridine-3-carboxylates. Similar reaction with β-aminocrotononitrile gave 5-hydroxy-2-methyl-5-(polyfluoroalkyl)-5H-chromeno[4,3-b]pyridine-3-carbonitriles.     

Synthesis of Polysubstituted 1,4-Dihydropyridines via Four-component Reactions of Arylamine,Acetylenedicarboxylate, Aromatic Aldehyde and Ethyl Acetoacetate

An efficient synthetic protocol for the 1,4-diaryl-1,4-dihydropyridines was developed via the domino four-component reaction of arylamine, acetylenedicarboxylate, aromatic aldehyde and ethyl acetoacetate. The reaction mechanism involves the formation of β-enamino ester and its sequential Michael addition to arylidene acetoacetate.     

A new three-component domino synthesis of 1,4-dihydropyridines

Cerium ammonium nitrate (CAN) catalyzed the three-component domino reaction between aromatic amines, α,β-unsaturated aldehydes, and ethyl acetoacetate, providing an efficient new entry into 1,4-dihydropyridines. This new reaction requires very mild reaction conditions, has water as the only side product and is complementary to the classical Hantzsch synthesis in that it is well suited to the preparation of N-aryl-5,6-unsubstituted dihydropyridines. Experiments in the presence of a radical trap suggest that a one-electron oxidative mechanism can be excluded and that CAN acts as a Lewis acid.     

A novel method for quantitative analysis of acetylacetone and ethyl acetoacetate by fluorine‐19 nuclear magnetic spectroscopy

A new method utilization of NMR spectra was developed for structural and quantitative analysis of enol forms of acetylacetone and ethyl acetoacetate. Acetylacetone and ethyl acetoacetate were determined by ¹⁹F NMR upon derivatisation with р‐fluorobenzoyl chloride. The base‐catalyzed derivatives of acetylacetone and ethyl acetoacetate reaction with р‐fluorobenzoyl chloride were analyzed by ¹H and ¹³C NMR spectroscopies. E and Z configurations of acetylacetone and ethyl acetoacetate were separated and purified by thin layer chromatography. In addition, the ability of ¹⁹F NMR for quantitative analysis of acetylacetone by integration of the appropriate signals of the derivatives were tested and compared. The results further testified the enol forms of acetylacetone and ethyl acetoacetate and the feasibility of ¹⁹F NMR method. This method can be potentially used to characterize E and Z isomers and quantitatively analyze E/Z ratio of β‐diketone and β‐ketoester homologues. Copyright © 2015 John Wiley & Sons, Ltd.     

Investigation of reaction of dimedone and ethyl acetoacetate with 1,2-epoxy-3-chloropropane

Reactions of dimedone and ethyl acetoacetate with 1,2-epoxy-3-chloropropane in the presence of K₂CO₃ in DMSO medium were investigated. The reaction of 1,2-epoxy-3-chloropropane with ethyl acetoacetate afforded ethyl 5-hydroxy-2-methyl-5,6-dihydro-4H-pyran-3-carboxylate, with dimedone, 3-(1′,2′-epoxypropyloxy)-5,5-dimethyl-cyclohex-2-en-1-one.     

Die Kinetik der Bromierung des Acetessigesters in wäßriger Lösung

TheEyring activation quantities, which are necessary for the explanation of the reaction mechanism, were calculated from the velocity coefficients of both bromination steps of ethyl acetoacetate in aqueous solution. The mean errors are also determined. The methods of evaluating the rate coefficients given byK. H. Meyer, Pedersen andBell are checked and classified.     

An efficient synthesis of 4H,5H-pyrano[3,4-c]pyran-4,5-diones from a suitably functionalized 2H-pyran-2-one

An efficient synthesis of ethyl 7-aryl-2-methyl-4H,5H-pyrano[3,4-c]pyran-4,5-dione-1-carboxylate 5, and ethyl 6-aryl-3-cyano-2H-pyran-2-one-4-acetate 6 has been delineated by reaction of suitably functionalized 2H-pyran-2-ones 1 with ethyl acetoacetate 2.     

Mild,four-component synthesis of 6-amino-4-aryl-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles catalyzed by titanium dioxide nano-sized particles

A convenient and efficient solvent-free procedure is described for preparation of 6-amino-4-aryl-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles by four-component reaction of hydrazine hydrate, ethyl acetoacetate, aryl aldehyde, and malononitrile in the presence of a catalytic amount of titanium dioxide nano-sized particles. Short reaction times, high yields under ambient conditions, simple reaction, clean work-up, and reusability of the nano heterogeneous catalyst are the advantages of this method.     

Cyclocondensation of F-2-methyl-2-pentene with activated methylene compounds using ‘freeze-dried’ potassium fluoride

The reactions of $\text{F}$-2-methyl-2-pentene with activated methylene compounds such as acetylacetone, ethyl acetoacetate, benzoylacetonitrile, and benzoylmethyl perfluoroalkyl ketones in the presence of potassium fluoride were carried out. Each reaction proceeded smoothly in acetonitrile at room temperature by using ‘freeze-dried’ potassium fluoride as a condensing agent. Acetylacetone and ethyl acetoacetate gave both divinyl ether and pyran compounds, whereas other activated methylene compounds afforded only pyrans in good yields.