- Preparation and Application of Silica Films Supported Imidazolium-Based Ionic Liquid as Efficient and Recyclable Catalysts for Benzoin Condensations
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Abstract: Two silica films -immobilized imidazolium-based ionic liquids (TMICl @silica films) were prepared, characterized and utilized as efficient catalysts for the benzoin reaction. Combined characterization results from FT-IR, elemental analysis, N2 adsorption–desorption isotherms and SEM, suggested that the imidazolium-based ionic liquids were successfully immobilized on the silica films. Moreover, the catalytic performance tests demonstrated that silica films immobilized imidazolium-based ionic liquids (ILs) exhibited excellent activity for the benzoin reactions of aromatic aldehydes. The influence of catalyst concentration, temperature and reaction duration on the catalytic activity were investigated by employing 0.7TMICl @silica film(catalyst C) as the catalyst. The results also showed that the benzoin condensations of aromatic aldehydes could give desired products with satisfactory yields under the optimized conditions. Additionally, the catalyst can be effortlessly separated by filtration and reused more than five times without significant loss of activity. Graphic Abstract: [Figure not available: see fulltext.]
- Qian, Cunwei,Yao, Changsheng,Yang, Liujun,Yang, Bo,Liu, Shuchun,Liu, Zongtang
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p. 1389 - 1396
(2019/11/21)
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- Synthesis of functionalized γ-lactones via a three-component cascade reaction catalyzed by consecutive N-heterocyclic carbene systems
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Two consecutive N-heterocyclic carbene (NHC) catalytic systems were combined in a one-pot cascade reaction for the assembly of aromatic aldehydes and 2-haloenals into a structurally complex γ-lactone backbone. To our knowledge, this is the first report of NHC-catalyzed [3 + 2] annulation of α,β-unsaturated acylazoliums with 1,2-bisnucleophiles.
- Zhao, Qian,Han, Bo,Wang, Biao,Leng, Hai-Jun,Peng, Cheng,Huang, Wei
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p. 26972 - 26976
(2015/03/30)
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- Unexpected transformation of aldehydes into benzoins with Copper(I)/Samarium
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The reductive coupling of aldehydes to afford pinacolic alcohols using all kinds of reducing agents involving samarium is well known. In this report, however, treatment of aromatic aldehydes with Cu(I)/Sm system produces benoins and/or benzils in good yields. A possible mechanism is proposed where Cu(I) not only activates the Sm metal but also promotes the dehydrogenation of the intermediates, during which a Cu(III) species may be involved. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Liu, Yongjun,Wang, Hui,Fu, Yulong,Qi, Yan,Yang, Kuiwei
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p. 259 - 266
(2013/12/04)
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- Synthesis, cytotoxic and antibacterial studies of p-benzyl-substituted NHC-silver(I) acetate compounds derived from 4,5-di-p-diisopropylphenyl- or 4,5-di-p-chlorophenyl-1H-imidazole
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4,5-Di(p-isopropylphenyl)-1H-imidazole (2a) and 4,5-di(p-chlorophenyl)-1H- imidazole (2b) were prepared from the appropriately substituted benzoin precursors and then reacted with five p-substituted benzyl halide derivatives through N-dibenzylation to the
- Streciwilk, Wojciech,Cassidy, Jennifer,Hackenberg, Frauke,Müller-Bunz, Helge,Paradisi, Francesca,Tacke, Matthias
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- One-pot asymmetric synthesis of substituted tetrahydrofurans via a multicatalytic benzoin/Michael/acetalization cascade
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A sequential benzoin/Michael/acetalization tandem reaction catalyzed by NHC and amine together has been developed to assemble aromatic aldehydes and enals into chiral tetrahydrofuran derivatives bearing multiple functional groups and stereogenic centers with high stereoselectivity of up to 95:5 dr and 96% ee. The high yield and stereocontrol of this process may be due to both acid-promoted symmetrization of racemic acyloins and iminium ion activation of enals.
- He, Gu,Wu, Fengbo,Huang, Wei,Zhou, Rui,Ouyang, Liang,Han, Bo
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supporting information
p. 2311 - 2319
(2014/07/21)
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- An organocatalytic ionic liquid
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The carbene concentration in 1-ethyl-3-methylimidazolium-acetate ionic liquid is sufficiently high to act as a catalyst in benzoin condensation, hydroacylation and also in oxidation of an alcohol by using CO2 and air. This observation reveals the potential of ionic liquid organocatalysts, uniting the beneficial properties of these two families of compounds.
- Kelemen, Zsolt,Holloczki, Oldamur,Nagy, Jozsef,Nyulaszi, Laszlo
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supporting information; experimental part
p. 5362 - 5364
(2011/09/13)
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- Acyl-CoA::cholesterol O-Acyl Transferase (ACAT) Inhibitors. 1. 2-(Alkylthio)-4,5-diphenyl-1H-imidazoles as Potent Inhibitors of ACAT
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A potent, bioavailable ACAT inhibitor may have beneficial effects in the treatment of atherosclerosis by (i) reducing the absorption of dietary cholesterol, (ii) reducing the secretion of very low density lipoproteins into plasma from the liver, and (iii) preventing the transformation of arterial macrophages into foam cells.We have found that a mevalonate derivative 2, which contains a 4,5-diphenyl-1H-imidazol-2-yl moiety, inhibits rat hepatic microsomal ACAT in vitro and produces a significant hypocholesterolemic effect in the cholesterol-fed rat.Structure-activity relationships for analogues of 2 demonstrate that the 4,5-diphenyl-1H-imidazole moiety is a pharmacophore for inhibition of rat microsomal ACAT.
- Harris, Neil V.,Smith, Christopher,Asthon, Michael J.,Bridge, Andrew W.,Bush, Raymond C.,et al.
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p. 4384 - 4392
(2007/10/02)
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- 5,6-Phenyl-2,3-dihydroimidazo [2,1-b] thiazoles
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The compounds are 5,6-phenyl-2,3-dihydroimidazo[2,1-b]thiazoles which have antiarthritic activity. A preferred compound is 5,6-bis(p-anisyl)-2,3-dihydroimidazo[2,1-b]thiazole.
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