15802-69-4Relevant academic research and scientific papers
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.
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.
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.
Design and synthesis of 4-alkyl-2-amino(acetamino)-6-aryl-1,3-thiazine derivatives as influenza neuraminidase inhibitors
Li, Wan,Xia, Lin,Hu, Aixi,Liu, Ailin,Peng, Junmei,Tan, Weiqing
, p. 635 - 644 (2013/09/24)
With a convenient and economical method, two series of 1,3-thiazine derivatives 1 and 2 were synthesized, and their neuraminidase (NA) inhibitory activities were evaluated. The pharmacological results showed that most of the compounds have potent NA inhibitory activity. Especially, 1g exhibited the best activity against influenza virus A (H1N1) NA (IC50 = 29.06 μg/mL), and its crystal structure was determined by single-crystal X-ray diffraction. The preliminary biological assay indicated that 1,3-thiazine could be used as a core structure to design novel influenza NA inhibitors. Two series of novel 1,3-thiazine analogs were synthesized and their neuraminidase (NA) inhibitory activities were evaluated. Most of the compounds have potent NA inhibitory activity. Compound 1g exhibited the best activity against influenza virus A (H1N1) NA with an IC50 of 29.06 μg/mL, and its crystal structure was determined by single-crystal X-ray diffraction.
Biocatalytic Knoevenagel reaction using alkaline protease from Bacillus licheniformis
Xie, Bang-Hua,Guan, Zhi,He, Yan-Hong
experimental part, p. 238 - 244 (2012/06/30)
BLAP (alkaline protease from Bacillus licheniformis) was used as a biocatalyst in the Knoevenagel condensations of aromatic, hetero-aromatic and α;β-unsaturated aldehydes with less reactive acetylacetone or ethyl acetoacetate. The reactions were performed in organic solvent in the presence of water. The functionalized trisubstituted alkenes and α,β,γ, δ-unsaturated carbonyl compounds could be obtained in moderate to good yields with E/Z selectivities up to >99:1. This biocatalytic reaction provided an alternative pathway for Knoevenagel condensation, which also demonstrates a novel case of unnatural activity of existing enzymes.
Enzyme catalytic promiscuity: The papain-catalyzed Knoevenagel reaction
Hu, Wen,Guan, Zhi,Deng, Xiang,He, Yan-Hong
experimental part, p. 656 - 661 (2012/05/04)
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.
A facile synthesis of trisubstituted alkenes from β-diketones and aldehydes with AlCl3 as catalyst
Li, Zheng-Nan,Chen, Xiao-Liang,Fu, Yu-Jie,Wang, Wei,Luo, Meng
experimental part, p. 25 - 35 (2012/05/20)
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.
An efficient iodine-catalysed Knoevenagel condensation reaction in the presence of acetic anhydride
Li, Zhong-Xian,Liu, Xiao-Pei,Qiu, Zhen,Xu, Dan,Yu, Xue-Jun
experimental part, p. 35 - 36 (2011/04/24)
A mild, simple and efficient iodine catalysed system has been developed for the Knoevenagel condensation of 1,3-dicarbonyl compounds with various aromatic aldehydes in the presence of acetic anhydride. The reaction gave good to excellent yields for a broad range of substrates.
Efficient solvent-free knoevenagel condensation between -diketone and aldehyde catalyzed by silica sulfuric acid
Zhang, Fuyi,Wang, Yu-Xin,Yang, Feng-Ling,Zhang, Hong-Yu,Zhao, Yu-Fen
scheme or table, p. 347 - 356 (2011/04/16)
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.
L-Histidine and L-arginine promote Knoevenagel reaction in water
Rahmati, Abbas,Vakili, Kobra
experimental part, p. 911 - 916 (2010/11/05)
Histidine and arginine were applied to the synthesis of trisubstituted alkenes through a condensation of an aldehyde with an activated CH-acid such as ethyl cyanoacetate, malononitrile, acetyl acetone or ethyl ace-toacetate during 5-12 h in water at room
