19411-75-7Relevant academic research and scientific papers
Accelerating the optimization of enzyme-catalyzed synthesis conditionsviamachine learning and reactivity descriptors
Liang, Jinhu,Liu, Dongchang,Wan, Zhongyu,Wang, Quan-De
supporting information, p. 6267 - 6273 (2021/07/28)
Enzyme-catalyzed synthesis reactions are of crucial importance for a wide range of applications. An accurate and rapid selection of optimal synthesis conditions is crucial and challenging for both human knowledge and computer predictions. In this work, a
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.
Efficient promiscuous Knoevenagel condensation catalyzed by papain confined in Cu3(PO4)2 nanoflowers
Yu, Jianyun,Chen, Xinxin,Jiang, Min,Wang, Anming,Yang, Linlin,Pei, Xiaolin,Zhang, Pengfei,Wu, Stephen Gang
, p. 2357 - 2364 (2018/02/06)
To develop an efficient and green immobilized biocatalyst for promiscuous catalysis which has a broad scope of applications, hybrid nanoflower (hNF) confined papain as a biocatalyst has been proposed and characterized in this study. hNFs were firstly prepared through mixing CuSO4 aqueous solution with papain in phosphate saline (PBS) at room temperature. The resulting hNFs were characterized by SEM and verified through a hydrolysis reaction with N-benzoyl-dl-arginine amide as substrate. Under optimal conditions, this nano-biocatalyst demonstrated a 15-fold hydrolytic activity compared with papain of free form, along with better thermal stability. A series of reaction factors (reaction temperature, time, and solvent) have been investigated for Knoevenagel condensation reactions with hNFs as catalyst. At optimal conditions, product yield of the hNFs catalyzed reaction was 1.3 fold higher than that of the free enzyme with benzaldehyde and acetylacetone as substrates. A few aldehydes and methylene compounds have also been used to test the generality and scope of this new enzymatic promiscuity. To sum up, the obtained hNFs demonstrate better catalytic properties than free papain and the inorganic metal-salt crystal can function as both support and promotor in biocatalysis.
Base-Promoted Tandem Cyclization for the Synthesis of Benzonitriles by C?C Bond Construction
Zhu, Cheng-Zhi,Wei, Yin,Shi, Min
supporting information, p. 808 - 813 (2018/01/27)
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.).
Construction of Multi-Substituted Benzenes via NHC-Catalyzed Reactions of Carboxylic Esters
Wu, Jichang,Mou, Chengli,Chi, Yonggui Robin
, p. 333 - 337 (2018/03/07)
A carbene-catalyzed ester activation reaction for the synthesis of multi-substituted benzenes is developed. Tetra-substituted benzene compounds are efficiently synthesized through this methodology. Compared with aldehyde substrates used in previous reports, the ester substrates used here are much more readily available and inexpensive. In addition, the TEMPO oxidant used here is more inexpensive than the quinones commonly used in related carbene-catalyzed reactions.
Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water
Xu, Hao,Pan, Liyang,Fang, Xiaomin,Liu, Baoying,Zhang, Wenkai,Lu, Minghua,Xu, Yuanqing,Ding, Tao,Chang, Haibo
supporting information, p. 2360 - 2365 (2017/05/29)
A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.
One-pot, three-component approach to the synthesis of 3,4,5-trisubstituted pyrazoles
Kamal, Ahmed,Sastry, K. N. Visweswara,Chandrasekhar,Mani, Geeta Sai,Adiyala, Praveen Reddy,Nanubolu, Jagadeesh Babu,Singarapu, Kiran Kumar,Maurya, Ram Awatar
, p. 4325 - 4335 (2015/05/13)
An operationally simple and high yielding protocol for the synthesis of polyfunctional pyrazoles has been developed through one-pot, three-component coupling of aldehydes, 1,3-dicarbonyls, and diazo compounds as well as tosyl hydrazones. The reaction proceeds through a tandem Knoevenagel condensation, 1,3-dipolar cycloaddition, and transition metal-free oxidative aromatization reaction sequence utilizing molecular oxygen as a green oxidant. The scope of the reaction was studied by varying the aldehyde, 1,3-dicarbonyl, and diazo component individually.
Organocatalytic knoevenagel condensations by means of carbamic acid ammonium salts
Mase, Nobuyuki,Horibe, Takuya
supporting information, p. 1854 - 1857 (2013/06/04)
The Knoevenagel condensation between an active methylene compound and an aromatic aldehyde with a carbamic acid ammonium salt used as an organocatalyst gave the desired Knoevenagel products in up to 98% yield. The reaction occurred at rt and in a short reaction time under solvent-free conditions. In addition, no extraction, wash, or chromatography steps were needed to obtain a high-purity Knoevenagel product.
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.
Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies
Ismail, Tarek M.A.,Saleh, Akila A.,Ghamry, Mosad A. El
experimental part, p. 276 - 288 (2012/01/31)
Tetradentate N2O2, N4 Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2- [(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4- chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza- dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15, 17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N4O2 Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, 1H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated.
