- Antimicrobial, antioxidant and SOD activities of copper(II) complexes derived from 2-aminobenzothiazole derivatives
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A series of Cu(II) complexes have been synthesized from bidentate Schiff base ligands (by condensation of Knoevenagel condensate of acetoacetanilide (obtained from substituted benzaldehydes and acetoacetanilide) and 2-aminobenzothiazole). They were charac
- Joseph,Janaki, G. Boomadevi,Nagashri,Joseyphus, R. Selwin
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Read Online
- Enzyme Promiscuity as a Remedy for the Common Problems with Knoevenagel Condensation
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A new protocol based on lipase-catalyzed tandem reaction toward α,β-enones/enoesters is presented. For the synthesis of the desired products the tandem process based on enzyme-catalyzed hydrolysis and Knoevenagel reaction starting from enol acetates and aldehyde is developed. The relevant impact of the reaction conditions including organic solvent, enzyme type, and temperature on the course of the reaction was revealed. It was shown that controllable release of the active methylene compound from the corresponding enol carboxylate ensured by enzymatic reaction diminishes significantly the formation of the unwanted co-products. Furthermore, this protocol was extended by including a second tandem chemoenzymatic transformation engaging various aldehyde precursors. After a careful optimization of the reaction conditions, the target products were obtained with yields up to 86 % and with excellent E/Z-selectivity.
- Koszelewski, Dominik,Ostaszewski, Ryszard
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p. 10156 - 10164
(2019/07/09)
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- Corrigendum to: Enzyme Promiscuity as a Remedy for the Common Problems with Knoevenagel Condensation (Chemistry – A European Journal, (2019), 25, 43, (10156-10164), 10.1002/chem.201901491)
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In the published paper, there is a mistake in the labelling of compounds in Figure. A corrected version of that Figure appears below. The authors apologise for the mistake. Figure (Figure presented.) Unsaturated 2,4-pentanediones obtained by enzyme-catalyzed tandem Knoevenagel reaction. Reaction conditions: aldehyde (1 mmol), 4-acetoxy-3-penten-2-one (5 a, R1=R2=R3=Me) (3 mmol), and PPL (100 mg) in tert-butyl alcohol/ 5 % H2O v/v (2 mL) for 72 h at 20 °C, 200 rpm. [a] With vinyl acetate. [b] With ethyl β-styrylcarbonate. [c] With styryl acetate.
- Koszelewski, Dominik,Ostaszewski, Ryszard
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p. 13647 - 13647
(2019/10/28)
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- Cross-linked polystyrene-TiCl4 complex as a reusable Lewis acid catalyst for solvent-free Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes
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Cross-linked polystyrene copolymer beads with the average particle size in the range of (50–80 mesh size) were prepared by a new method, characterized and functionalized with titanium tetrachloride to afford the corresponding polystyrene?titanium tetrachloride complex in one step reaction and characterized by FT-IR, UV, TGA, DSC, XRD, SEM, BET. This polymer metal complex (PS/TiCl4) was used as a heterogeneous, recoverable, reusable Lewis acid for solvent-free Knoevenagel condensations of 1,3-diketones with aromatic aldehydes under green and mild conditions. The rate of reactions was found to decrease with an increasing percentage of crosslinking and the mesh size of the copolymer beads. This complex showed good stability and catalytic activity in the Knoevenagel reactions.
- Rahmatpour, Ali,Goodarzi, Niloofar
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- Base-Promoted Tandem Cyclization for the Synthesis of Benzonitriles by C?C Bond Construction
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A facile synthesis of benzonitriles via a base-promoted tandem cyclization reaction of α,β-unsaturated enones having electron-withdrawing group (EWG) and 2-acyl-acrylonitriles was developed. This new synthetic method to access benzonitriles is suitable for a wide range of substrates. A plausible reaction mechanism is proposed on the basis of previous literature and our own investigations. (Figure presented.).
- Zhu, Cheng-Zhi,Wei, Yin,Shi, Min
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supporting information
p. 808 - 813
(2018/01/27)
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- COMPOSITIONS AND METHODS FOR STABILIZING INGREDIENTS USING 2,4-PENTANEDIONE COMPOUNDS
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Benzylidene substituted 2,4-pentanedione compounds without having phenolic hydroxyl group(s) are found to provide photostability to otherwise photosensitive compounds and compositions.
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- A facile synthesis of trisubstituted alkenes from β-diketones and aldehydes with AlCl3 as catalyst
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Preparation of trisubstituted alkenes from low-activity β-diketones and aldehydes with aluminum chloride as catalyst has been studied. The frequently used catalyst AlCl3 is used for the first time to promote this condensation. The procedure is a convenient, low toxicity, and highly efficient method for industrial synthesis of trisubstituted alkenes in high yield. Springer Science+Business Media B.V. 2011.
- Li, Zheng-Nan,Chen, Xiao-Liang,Fu, Yu-Jie,Wang, Wei,Luo, Meng
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experimental part
p. 25 - 35
(2012/05/20)
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- Enzyme catalytic promiscuity: The papain-catalyzed Knoevenagel reaction
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Papain as a sustainable and inexpensive biocatalyst was used for the first time to catalyze the Knoevenagel reactions in DMSO/water. A wide range of aromatic, hetero-aromatic and α,β-unsaturated aldehydes could react with less active methylene compounds acetylacetone and ethyl acetoacetate. The products were obtained in moderate to excellent yields with Z/E selectivities of up to 100:0. This case of biocatalytic promiscuity not only widens the application of papain to new chemical transformations, but also could be developed into a potentially valuable method for organic synthesis.
- Hu, Wen,Guan, Zhi,Deng, Xiang,He, Yan-Hong
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experimental part
p. 656 - 661
(2012/05/04)
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- Efficient solvent-free knoevenagel condensation between -diketone and aldehyde catalyzed by silica sulfuric acid
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Silica sulfuric acid has been utilized as an efficient heterogeneous recyclable catalyst for Knoevenagel condensation between poorly reactive β-diketones and aldehydes under solvent-free conditions. This protocol also works well with more reactive β-ketoesters. The condensation is efficient, clean, and mild. The scope and generality of the Knoevenagel condensation were investigated. The procedure led only to the Knoevenagel product, and no side product derived from a subsequent Michael βaddition of -diketone to alkene was detected at rt. Increasing temperature led to a subsequent Michael addition, and it was applied to the efficient synthesis of 9-aryl-1,8-dioxo- octahydroxanthene derivatives.
- Zhang, Fuyi,Wang, Yu-Xin,Yang, Feng-Ling,Zhang, Hong-Yu,Zhao, Yu-Fen
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scheme or table
p. 347 - 356
(2011/04/16)
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- A systematic study on Knoevenagel reaction and Nazarov cyclization of less reactive carbonyl compounds using rare earth triflates and its applications
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A systematic study of Knoevenagel reaction and Nazarov cyclization was made on variety of less reactive carbonyl compounds such as β-ketoesters, 1,3-diketones and cyclic active methylene compounds using Yb(OTf)3 as the catalyst. Recycling study confirms reusability of the catalyst without much loss of activity.
- Ilangovan,Muralidharan,Maruthamuthu
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experimental part
p. 1000 - 1006
(2012/02/05)
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- Catalysis by L-lysine: A green method for the condensation of aromatic aldehydes with acidic methylene compounds in water at room temperature
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The condensation of aromatic aldehydes with acidic methylene compounds such as ethyl benzoylacetate, 2,4-pentanedione and dimedone proceeded efficiently in pure water in the presence of L-lysine at room temperature. Interestingly, there are two different
- Zhang, Yan,Sun, Cuizhi,Liang, Jun,Shang, Zhicai
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experimental part
p. 2255 - 2259
(2011/10/09)
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- Solvent-free NbCl5 catalyzed condensation of 1,3-dicarbonyl compounds and aldehydes: a facile synthesis of trisubstituted alkenes
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A simple preparation of trisubstituted alkenes by condensation of β-diketones or β-ketoesters with aldehydes in presence of NbCl5 as a Lewis acid catalyst in solvent-free conditions is described.
- Yadav,Bhunia, Dinesh C.,Singh, Vinay K.,Srihari
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experimental part
p. 2470 - 2473
(2009/08/09)
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- Synthesis and biological evaluation of a novel series of 1,5-benzothiazepine derivatives as potential antimicrobial agents
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Two series of novel 1,5-benzothiazepine derivatives (23 compounds) were efficiently synthesized and evaluated for antibacterial and antifungal activities. The results indicated that the compounds possessed a broad spectrum of activity against the tested microorganisms and showed higher activity against fungi than bacteria. Compound 2e exhibited the greatest antimicrobial activity. Preliminary study of the structure-activity relationship revealed that substituents in phenyl rings had a great effect on the antimicrobial activity of these compounds.
- Wang, Lanzhi,Zhang, Ping,Zhang, Xuemei,Zhang, Yonghong,Li, Yuan,Wang, Yongxiang
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experimental part
p. 2815 - 2821
(2009/10/02)
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- Reaction of aromatic aldehydes with β-dicarbonyl compounds in a catalytic system: Piperidinium acetate - 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid
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Condensation of aromatic (heteroaromatic) aldehydes with 1,3-dicarbonyl compounds under the 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) ionic liquid - piperidinium acetate catalytic system (0.2 equiv. of each component) in the absence of a solvent affords, depending on the structures of the reagents, 2-arylidene derivatives of methyl acetoacetate and acetylacetone, diethyl 2,4-bis(trifluoroacetyl)-3-phenylpentanedioate, or dimethyl 2-aryl-4-hydroxy-6-oxocyclohexane-1,3-dicarboxylates. The reactions of the resulting 2-arylidene derivatives with O-methylisourea in the [Bmim][BF 4] ionic liquid produced methyl 2-methoxy-4-methyl-6- aryldihydropyrimidine-5-carboxylates and 1-(2-methoxy-4-methyl-6- phenyldihydropyrimidin-5-yl)ethanone (mixtures of 3,6- and 1,6-dihydro isomers), which were transformed into the corresponding 3,4-dihydropyrimidin-2(1H)-one derivatives.
- Putilova,Troitskii,Zlotin
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p. 1233 - 1238
(2007/10/03)
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- ZrOCl2.8H2O as a new solid phase and recyclable catalyst for an efficient Knoevenagel condensation under solvent-free microwave irradiation conditions
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A new solid phase and recyclable catalyst for an efficient Knoevenagel condensation under solvent-free microwave irradiation conditions has been developed for universal applications in C-C bond formation.
- Yakaiah,Venkat Reddy,Lingaiah,Shanthan Rao,Narsaiah
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p. 1301 - 1303
(2007/10/03)
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- Knoevenagel condensation catalyzed by USY zeolite
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The Knoevenagel condensation of substituted benzaldehydes with active methylene compounds was performed very efficiently by using a USY (ultrastable Y) zeolite as heterogeneous catalyst.
- Wang,Ma, YuDao,Zuo, BoJun
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p. 4107 - 4110
(2007/10/03)
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- Substituted beta-diketones and their use
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Compounds of formula wherein n is 0 or 1, R1 and R2 are independently methyl, ethyl or cyclopropyl and R is an optionally substituted phenyl or heteroaryl group or salt or ester thereof are useful in the treatment of inflammatory bowel disease.
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- The Complex Reaction of Acetohydrazides with Unsaturated Diketones: Alternative Cyclizations to 1,2-Diazepin-3-ones and Pyrazolopyridines
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The reaction of 2-cyanoacetohydrazide (1) and 2-(ethoxycarbonyl)acetohydrazide (26) with unsaturated 1,3-diketones leading with moderate yields to 1,2-diazepinones (3, 23, 24) and pyrazolopyridines (5, 15, 20, 25) together with the corresponding acetohydrazones have been studied.The reaction course depends on the temperature and the relative reactivity of the carbonyl groups of the starting materials.When one of these carbonyl groups is less reactive (benzoyl or ethoxycarbonyl groups), the reaction does not yield diazepinones but only pyrazolopyridines and/or acetohydrazones.
- Alonso, Paloma,Martin-Leon, Nazario,Quinteiro, Margarita,Seoane, Carlos,Soto, Jose L.
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p. 841 - 846
(2007/10/02)
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- SEQUENTIAL ACETALIZATION-PYROLYSIS OF α-ACETYL BENZALACETONES. A METHOD FOR THE GENERATION OF 6-SUBSTITUTED 2-ACETONAPHTHONES
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6-Substituted 2-acetonaphthones can be generated from para substituted benzaldehydes and acetylacetone (2,4-pentanedione) in three reactions consisting of condensing the benzaldehyde with acetylacetone, acetalizing the resultant 3-benzylidene 2,4-pentanedione (α-acetyl benzalacetones), with trimethyl orthoformate, pyrolyzing the acetal either in the vapor phase at 475 deg C or by heating in a high boiling solvent, such as 1-methylnaphthalene.
- Zoeller, Joseph R.
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p. 1457 - 1460
(2007/10/02)
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- Utilisation of 13C N.M.R. Spectroscopy for the Identification of E- and Z-α,β-Unsaturated Esters, Ketones and Nitriles.
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Measurement of 3JCO,H coupling constants provides an unambiguous procedure for the configurational analysis of substituted 2- and 3-arylpropenoic esters and of E- and Z-2-arylbut-2-en-1,4-dioates, even when only one of the isomers is available for analysis.An analogous procedure can also be used for the configurational analysis of 3-arylpropenonitriles and of 4-arylbut-3-en-2-ones.
- Gregory, Barrie,Hinz, Werner,Jones, R. Alan,Arques, Jose Sepulveda
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p. 2801 - 2821
(2007/10/02)
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- Methyl vs. Methylene Condensation of Aromatic Aldehydes with 1,1,1-Trifluoroacetylacetone
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From the slow Knoevenagel condensations of 1,1,1-trifluoroacetylacetone (4) with aromatic aldehydes in benzene in the presence of piperidine-AcOH, low yields of three products were isolated: the enol form of the methyl-condensation product ArCH=CHCOCH=C(O
- Gazit, Aviv,Rappoport, Zvi
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p. 2863 - 2870
(2007/10/02)
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- Substituent Effects on 13C and 1H Chemical Shifts in 3-Benzylidene-2,4-pentanediones
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Substituent effects on the 13C and 1H chemical shifts have been studied for derivatives of 3-benzylidene-2,4-pentanedione.A significant correlation has been found between chemical shifts of the Z carbonyl group and (C-2) and Hammett constants, while no correlation has been found for the E carbonyl group (C-4).Attempts have been made to determine the structural factors which influence these effects.The conformation of 3-benzylidene-2,4-pentanediones has been determined by 13C and 1H NMR spectroscopy.
- Solcaniova, E.,Hrnciar, P.,Liptaj, T.
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