4728-04-5Relevant articles and documents
Pyridine immobilised on magnetic silica as an efficient solid base catalyst for Knoevenagel condensation of furfural with acetyl acetone
Tarade, Komal,Shinde, Suhas,Sakate, Sachin,Rode, Chandrashekhar
, p. 81 - 85 (2019)
Novel heterogeneous pyridine immobilised magnetic silica (Fe3O4@SiO2-Py) was found to be an efficient, greener and heterogeneous solid base catalyst for the Knoevenagel condensation of furfural with acetylacetone under optimized reaction conditions. The Knoevenagel condensation product 3-(2-furylmethylene)-2,4-pentanedione (FMP), a jet fuel precursor, was produced in high yield of 85% with 94% conversion of furfural at 100 °C within a period of 4 h. Fe3O4@SiO2-Py catalyst showed excellent stability and recyclability without losing its initial activity.
Synthesis, characterization, DNA binding, oxidative damage of DNA strand scission, and antimicrobial activities of β-diketone condensed Schiff-base transition metal complexes
Raman,Jeyamurugan,Rani, R. Usha,Baskaran,Mitu
, p. 1629 - 1644 (2010)
Co(II), Ni(II), Cu(II), Zn(II), and VO(IV) complexes containing a versatile β-diketone Schiff-base ligand (obtained by the condensation of 3-furan-2-ylmethylene-2,4-dione and 2-aminophenol) have been synthesized and characterized. Microanalytical, magnetic, and spectroscopic data reveal that the central metal is coordinated to two oxygens of phenolate and two nitrogens of imine of the ligand. Binding of synthesized complexes with calf thymus DNA has been investigated by spectroscopic and electrochemical methods and viscosity measurements. The complexes are able to form adducts with DNA and to distort the double helix by changing the base stacking. Electrostatic binding of vanadyl complex is observed from the weak hypochromism in electronic absorption spectra and no change in the viscosity with DNA. Oxidative DNA cleavage activities of the complexes are studied with supercoiled pUC19 DNA using gel electrophoresis. The hydroxyl radical (OH?) is likely to be the species responsible for the cleavage of pUC19 DNA by the synthesized complexes. Under our experimental conditions, the vanadyl complex has no significant cleavage of DNA. The compounds have been screened for activity against several bacterial and fungal strains and the results are compared with the activity of standard drugs.
Enzyme Promiscuity as a Remedy for the Common Problems with Knoevenagel Condensation
Koszelewski, Dominik,Ostaszewski, Ryszard
, p. 10156 - 10164 (2019/07/09)
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.
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)
Koszelewski, Dominik,Ostaszewski, Ryszard
, p. 13647 - 13647 (2019/10/28)
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.
Cross-linked polystyrene-TiCl4 complex as a reusable Lewis acid catalyst for solvent-free Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes
Rahmatpour, Ali,Goodarzi, Niloofar
, p. 24 - 31 (2019/03/08)
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.
Highly efficient Nb2O5 catalyst for aldol condensation of biomass-derived carbonyl molecules to fuel precursors
Jing, Yaxuan,Xin, Yu,Guo, Yong,Liu, Xiaohui,Wang, Yanqin
, p. 1168 - 1177 (2019/07/09)
Aldol condensation is of significant importance for the production of fuel precursors from biomass-derived chemicals and has received increasing attention. Here we report a Nb2O5 catalyst with excellent activity and stability in the aldol condensation of biomass-derived carbonyl molecules. It is found that in the aldol condensation of furfural with 4-heptanone, Nb2O5 has obviously superior activity, which is not only better than that of other common solid acid catalysts (ZrO2 and Al2O3), more importantly, but also better than that of solid base catalysts (MgO, CaO, and magnesium-aluminum hydrotalcite). The detailed characterizations by N2 sorption/desorption, NH3-TPD, Py-FTIR and DRIFTS study of acetone adsorption reveal that Nb2O5 has a strong ability to activate the C=O bond in carbonyl molecules, which helps to generate a metal enolate intermediate and undergo the nucleophilic addition to form a new C–C bond. Furthermore, the applicability of Nb2O5 to aldol condensation is extended to other biomass-derived carbonyl molecules and high yields of target fuel precursors are obtained. Finally, a multifunctional Pd/Nb2O5 catalyst is prepared and successfully used in the one-pot synthesis of liquid alkanes from biomass-derived carbonyl molecules by combining the aldol condensation with the sequential hydrodeoxygenation.
Exploration of the Role of Double Schiff Bases as Catalytic Intermediates in the Knoevenagel Reaction of Furanic Aldehydes: Mechanistic Considerations
Van Schijndel, Jack,Canalle, Luiz Alberto,Molendijk, Dennis,Meuldijk, Jan
supporting information, p. 1983 - 1988 (2018/09/18)
This paper presents mechanistic considerations on an efficient, green, and solvent-free Knoevenagel procedure for the chemical transformation of furanic aldehydes into their corresponding α,β-unsaturated compounds. In the proposed mechanism furanic aldehydes react with ammonia, released from ammonium salts, to form a catalytically active double Schiff base. The catalytic intermediates involved in the condensation step are characterized.
Enantioselective Synthesis of 2,3-Dihydrofurans via Ammonium Ylides
Worgull, Dennis,?hler, Laura,Strache, Joss Pepe,Friedrichs, Teresa,Ullrich, Patrick
supporting information, p. 6077 - 6080 (2017/11/14)
A chiral, ammonium ylide based access to tetrasubstituted 2,3-dihydrofurans starting from readily available benzylidene dicarbonyls and bromo acetophenones has been developed. The products are obtained in moderate to good yields with excellent diasteroselectivity and good to excellent enantioselectivity (up to 99:1 e.r.). The employed chiral amine can be recovered in near quantitative yield. The transformation can be run as a three-component one-pot reaction, generating the ammonium salt and ylide in situ. The scope of this reaction includes 17 new dihydrofurans with aromatic or heteroaromatic substituents.
Synthesis of Furanyl β-Diketone-based Heteroleptic Iridium(III) Complexes and Studies of Their Photo-Luminescence Properties
Saha, Sukdeb,Rozenberg, Illya,Lemcoff, N. Gabriel
supporting information, p. 2460 - 2465 (2015/11/16)
Four iridium complexes containing furan moieties were synthesized and characterized. The positioning of the furan unit had a strong effect on the optical properties of the complexes. The synthetic methodologies developed pave the way for the introduction of oligofuran compounds in IrIII heteroleptic complexes for OLED applications.
Knoevenagel condensation of aromatic aldehydes with active methylene compounds catalyzed by lipoprotein lipase
Ding, Yan,Ni, Xiao,Gu, Mengjie,Li, Shuang,Huang, He,Hu, Yi
, p. 101 - 104 (2015/02/19)
A screening of using different lipases to catalyze the Knoevenagel reaction was realized, and lipase lipoprotein (LPL) from Aspergillus niger showed the best catalytic performance. The reaction conditions including solvent, enzyme loading, and temperature were screened to improve the reaction efficiency. Various kinds of substrates were investigated, and almost all the target products were obtained in good to excellent yields (76-98%) with Z configuration exclusively. This procedure provides a novel, green and efficient method for the Knoevenagel condensation of aromatic aldehydes with active methylene compounds.
