- Efficient and mild benzoin condensation reaction catalyzed by simple 1-N-alkyl-3-methylimidazolium salts
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The benzoin reaction, catalyzed by simple 1-N-alkyl-3-methylimidazolium salt-based ionic liquid via carbene intermediate, to give the α-hydroxyl ketone proceeds in CH2Cl2 under mild conditions.
- Xu, Li-Wen,Gao, Yang,Yin, Jian-Jun,Li, Lyi,Xia, Chun-Gu
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Read Online
- Reduction of 1,2-dicarbonyl compounds mediated by the combination of phosphine and lewis acid
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The combination of Ph3P/AlBr3 effectively promoted the reduction of several 1,2-dicarbonyl compounds in the presence of water (1.0 equiv) and the corresponding α-hydroxy carbonyl compounds were obtained in good yields.
- Kikuchi, Satoshi,Hashimoto, Yukihiko
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Read Online
- A new protocol for one-pot synthesis of tetrasubstituted pyrroles using tungstate sulfuric acid as a reusable solid catalyst
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A variety of tetrasubstituted pyrroles were synthesized in good yields in a one-pot, three-component reaction of α-hydroxyketones, malononitrile, and ammonium acetate using tungstate sulfuric acid (TSA) under solvent-free conditions.
- Farahi, Mahnaz,Davoodi, Mahdiyeh,Tahmasebi, Mina
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Read Online
- N-PEGylated Thiazolium Salt: A Green and Reusable Homogenous Organocatalyst for the Synthesis of Benzoins and Acyloins
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N-PEGylated-thiazolium salt is used as efficient catalyst for the benzoin condensation. The catalyst was synthesized by reaction of activated polyethylene glycol 10,000 (PEG-10000) with 4-methyl-5-thiazoleethanol (sulfurol). Reaction mixture undergoes temperature-assisted phase transition and catalyst separated by simple filtration. After reaction course, catalyst can be recycled and reused without any apparent loss of activity which makes this process cost effective and hence ecofriendly. Synthesized benzoins and acyloins by this method have been characterized on the basis of melting point and 1H-NMR spectral studies. Graphic Abstract: [Figure not available: see fulltext.]
- Haghighi, Ali Javaheri,Mokhtari, Javad,Karimian, Khashayar
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p. 1646 - 1652
(2020/10/19)
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- Organocatalytic Synthesis of Substituted Vinylene Carbonates
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The organocatalytic synthesis of substituted vinylene carbonates from benzoins and acyloins was studied using diphenyl carbonate as a carbonyl source. A range of N-Heterocyclic Carbene (NHC) precursors were screened and it was found that imidazolium salts were the most active for this transformation. The reaction occurs at 90 °C under solvent-free conditions. A wide range of substituted vinylene carbonates (symmetrical and unsymmetrical, aromatic or aliphatic), including some derived from natural products, were prepared with 20–99% isolated yields (24 examples). The reaction was also developed using thermomorphic polyethylene-supported organocatalysts as recoverable and recyclable species. The use of such species facilitates the workup and allows the synthesis of vinylene carbonates on the preparative scale (>30 g after 5 runs). (Figure presented.).
- Onida, Killian,Haddleton, Alice J.,Norsic, Sébastien,Boisson, Christophe,D'Agosto, Franck,Duguet, Nicolas
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supporting information
p. 5129 - 5137
(2021/09/18)
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- Zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source
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The zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source and zinc as reductant was successfully conducted. The presented method provides a low-cost, environmentally friendly and practical preparation of α-aryl amino esters, α-hydroxyketones and phenylethylenes. By using D2O as deuterium source, the corresponding products were obtained in high efficiency with excellent deuterium incorporation rate, which gives a cheap and safe tool for access to valuable deuterium-labelled compounds. This journal is
- Shen, Guoli,Liu, Haojie,Chen, Jingchao,He, Zhenxiu,Zhou, Yongyun,Wang, Lin,Luo, Yang,Su, Zhimin,Fan, Baomin
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supporting information
p. 3601 - 3610
(2021/05/04)
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- 1-butyl-3-methylimidazolium bromide as a solvent and precatalyst for stetter reaction
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Stetter reaction between aromatic aldehydes and acrylonitrile/ethyl acrylate performing in [Bmim]Br in the presence of NaOH is described. N-Heterocyclic carbene (NHC) generates in situ is shown to be an efficient catalyst. Benzoin condensation also occured as side reaction.
- Phungpis, Baramee,Hahnvajanawong, Viwat
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p. 2028 - 2032
(2020/09/02)
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- 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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- N-Heterocyclic Carbene Acyl Anion Organocatalysis by Ball-Milling
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The ability to conduct N-heterocyclic carbene-catalysed acyl anion chemistry under ball-milling conditions is reported for the first time. This process has been exemplified through applications to intermolecular-benzoin, intramolecular-benzoin, intermolecular-Stetter and intramolecular-Stetter reactions including asymmetric examples and demonstrates that this mode of mechanistically complex organocatalytic reaction can operate under solvent-minimised conditions.
- Nicholson, William I.,Seastram, Alex C.,Iqbal, Saqib A.,Reed-Berendt, Benjamin G.,Morrill, Louis C.,Browne, Duncan L.
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p. 131 - 135
(2019/12/11)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- The Direct Conversion of α-Hydroxyketones to Alkynes
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Alkynes are highly important functional groups in organic chemistry, both as part of target structures and as versatile synthetic intermediates. In this study, a protocol for the direct conversion of α-hydroxyketones to alkynes is reported. In combination with the variety of synthetic methods that generate the required starting materials by forming the central C-C bond, it enables a highly versatile fragment coupling approach toward alkynes. A broad scope for this novel transformation is shown alongside mechanistic insights. Furthermore, the utility of our protocol is demonstrated through its application in concert with varied α-hydroxyketone syntheses, giving access to a broad spectrum of alkynes.
- Ghiringhelli, Francesca,Nattmann, Lukas,Bognar, Sabine,Van Gemmeren, Manuel
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p. 983 - 993
(2019/01/24)
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- Benzoin compound preparing method
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The invention provides a benzoin compound preparing method. Specifically, the benzoin compound preparing method takes mesoporous material immobilized imidazolium salt ion liquid as catalysts to catalyze aromatic aldehydes into various benzoin compounds. T
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Paragraph 0062; 0063
(2019/05/02)
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- A novel bi-functional surfactant-based paramagnetic deep-eutectic catalyst for improved benzoin condensation and multi-component synthesis of pyrrole derivatives
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A new professional magnetic surfactant-based deep-eutectic (DE) and viscose liquefy catalyst (GS2+·2FeCl4, MGSFe) was synthesized by an optimized reaction of the as-prepared cationic gemini-surfactant (GS) with two moles of FeCl3·6H2O. The structure of the GS and MGSFe were characterized by NMR, FT-IR, UV–visible, CHN, pH, surface tension (?), and vibrating sample magnetometry (VSM) analyses. The MGSFe, that is a high viscose brownish liquid at >50 °C, was successfully tested as a highly active paramagnetic catalyst for improved benzoin condensation and three-component synthesis of substituted pyrroles with the highest turnover number (TON) and turnover frequency (TOF) that ever reported for this purpose. The superior activity of MGSFe is due to its amphiphile properties, the synergistic effects between GS2+ and 2FeCl4 ? as hydrogen-bond-donor and magnetic hydrogen-bond-acceptor components of this novel magneto-responsive DE, and reusability without loss of activity even in four consequence cycles run for synthesis of pyrroles. This magnetic GS-based DE can be used as oil miscible additive, pollutant adsorbent, and carrier of biomaterials to targeted poisons.
- Tamaddon, Fatemeh,Tadayonfar, SeydEhsan
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- Synthesis, anti-proliferative evaluation, and molecular docking studies of 3-(Alkylthio)-5,6-diaryl-1,2,4-triazines as tubulin polymerization inhibitors
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Background: The role of microtubules in cell division and signaling, intercellular transport, and mitosis has been well known. Hence, they have been targeted for several anti-cancer drugs. Methods: A series of 3-(alkylthio)-5,6-diphenyl-1,2,4-triazines were prepared and evaluated for their cytotoxic activities in vitro against three human cancer cell lines; human colon carcinoma cells HT-29, human breast adenocarcinoma cell line MCF-7, human Caucasian gastric adenocarcinoma cell line AGS as well as fibroblast cell line NIH-3T3 by MTT assay. Docking simulation was performed to insert these compounds into the crystal structure of tubulin at the colchicine binding site to determine a probable binding model. Compound 5d as the most active compound was selected for studying of microtubule disruption. Results: Compound 5d showed potent cytotoxic activity against all cell lines. The molecular modeling study revealed that some derivatives of triazine strongly bind to colchicine binding site. The tubulin polymerization assay kit showed that the cytotoxic activity of 5d may be related to inhibition of tubulin polymerization. Conclusion: The cytotoxicity and molecular modeling study of the synthesized compounds with their inhibition activity in tubulin polymerization demonstrate the potential of triazine derivatives for development of new anti-cancer agents.
- Saravani, Farhad,Moghadam, Ebrahim Saeedian,Salehabadi, Hafezeh,Ostad, Seyednasser,Hamedani, Morteza Pirali,Amanlou, Massoud,Faramarzi, Mohammad Ali,Amini, Mohsen
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p. 1194 - 1201
(2019/11/22)
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- COMPOUNDS AND USES THEREOF IN THE TREATMENT OF CANCERS AND OTHER MEDICAL CONDITIONS
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There are provided compounds, their preparation and their use in the treatment of medical conditions including cancers and immune disorders.
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Paragraph 0101; 0103; 0112; 00128
(2017/02/09)
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- NaBrO3/bmim[HSO4]: a versatile system for the selective oxidation of 1,2-diols, α-hydroxyketones, and alcohols
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Abstract: Sodium bromate with bmim[HSO4] has been found to be an excellent oxidizing agent in aqueous medium. NaBrO3:bmim[HSO4] oxidized 1,2-diols, α-hydroxyketones, and alcohols to the corresponding carbonyl compounds in excellent yields. This method offers advantages such as low cost reagents, aqueous reaction conditions, moderate temperatures and short reaction times and hence environmentally benign reaction. Moreover, the ionic liquid bmim[HSO4] could be recycled for at least three times without loss of significant activity. Graphical abstract: [Figure not available: see fulltext.]
- Khurana, Jitender M.,Lumb, Anshika,Chaudhary, Ankita
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p. 381 - 386
(2017/02/10)
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- Highly efficient asymmetric hydrogenation of cyano-substituted acrylate esters for synthesis of chiral γ-lactams and amino acids
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A highly efficient and enantioselective synthesis of γ-lactams and γ-amino acids by Rh-catalyzed asymmetric hydrogenation has been developed. Using the Rh-(S,S)-f-spiroPhos complex, under mild conditions a wide range of 3-cyano acrylate esters including both E and Z-isomers and β-cyano-α-aryl-α,β-unsaturated ketones were first hydrogenated with excellent enantioselectivities (up to 98% ee) and high turnover numbers (TON up to 10 000).
- Kong, Duanyang,Li, Meina,Wang, Rui,Zi, Guofu,Hou, Guohua
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supporting information
p. 1216 - 1220
(2016/02/03)
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- Palladium-Catalyzed Chemo- and Enantioselective C?O Bond Cleavage of α-Acyloxy Ketones by Hydrogenolysis
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A chemoselective C?O bond cleavage of the ester alkyl side-chain of α-acyloxy ketones was realized for the first time by a highly efficient palladium-catalyzed hydrogenolysis (S/C=6000, the highest catalytic efficiency by far). Furthermore, a kinetic resolution of α-acyloxy ketones was first developed by enantioselective hydrogenolysis with good yields and up to 99 % ee.
- Chen, Jianzhong,Zhang, Zhenfeng,Liu, Delong,Zhang, Wanbin
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supporting information
p. 8444 - 8447
(2016/07/19)
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- SnCl2·2H2O-Catalyzed Solvent-Free Synthesis of α-Amino Ketones and Tetrasubstituted Pyrazines
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Solvent-free reaction of various anilines with α-hydroxy ketones catalyzed by SnCl2·2H2O provides α-amino ketones in excellent yields. While a similar reaction with aliphatic amines is applicable for the synthesis of substituted pyrazines, SnCl2·2H2O permits versatility in the solvent-free reaction of α-hydroxy ketones with ammonium acetate to give the corresponding substituted pyrazines in good to excellent yields.
- Tamaddon, Fatemeh,Dehghani Tafti, Arefeh
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p. 2217 - 2220
(2016/10/11)
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- Cocamidopropyl betaine catalyzed benzoin condensation and pseudo-four-component reaction of the in situ formed benzoin in water
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An improved synthesis of benzoins, as key synthetic building blocks, and substituted pyrroles in micelle medium using a very small amount of cocamidopropyl betaine in water is described. In this one-pot strategy, benzoin condensation of aldehydes and further pseudo-four-component reaction of the in situ formed benzoin with 1,3-dicarbonyls, and ammonium acetate gave excellent yields of the desired pyrrole products.
- Tamaddon, Fatemeh,Alizadeh, Masoomeh
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p. 525 - 530
(2015/04/14)
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- Highly enantioselective hydrogenation of o-alkoxy tetrasubstituted enamides catalyzed by a Rh/(R, S)-josiphos catalyst
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Rh/(R,S)-JosiPhos complex-catalyzed asymmetric hydrogenation of o-alkoxy tetrasubstituted enamides has been achieved, and it furnished a set of β-amino alcohol analogues in high yields and excellent enantiomeric excesses (>99% conversion, up to 99% ee).This method provides valuable chiral building blocks in chiral pharmaceuticals and useful motifs for catalysts.
- Meng, Jingjing,Gao, Min,Lv, Hui,Zhang, Xumu
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supporting information
p. 1842 - 1845
(2015/04/27)
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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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- Benzoin condensation and stetter reaction catalysed by N,N-dimethylbenzimidazolium iodide in [Bmim][OH]
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N,N-Dimethylbenzimidazolium iodide catalysed benzoin condensation and Stetter reaction in 1-butyl-3-methylimidazolium hydroxide [bmim][OH] which acts as a basic catalyst as well as a solvent for the reactions are described. The recycled reaction media containing benzimidazolium salt can be reused for several times without significant loss of efficiency.
- Phungpis, Baramee,Hahnvajanawong, Viwat,Theramongkol, Parinya
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p. 933 - 939
(2015/02/19)
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- Poly(4-vinylimidazolium) iodides: A highly recyclable organocatalyst precursor for benzoin condensation reaction
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The development of highly efficient, recyclable poly(4-vinylimidazolium) iodides (2) for the benzoin condensation reaction under mild reaction conditions is discussed: poly(4-vinyl N-heterocyclic carbene)s (3) obtained from 2 showed higher catalytic activity than monomeric 4-vinyl N-heterocyclic carbene and could be successfully recovered and reused over seven times without loss of performance. the Partner Organisations 2014.
- Seo, Ue Ryung,Chung, Young Keun
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p. 32371 - 32374
(2014/08/18)
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- Synthesis and anticancer activity of 2,4,5-triaryl imidazole derivatives
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This study describes the synthesis of four 2,4,5-triarylimidazole derivatives and their anticancer activities. The target compounds were prepared from the reaction of benzaldehyde and benzoin derivatives in presence of ammonium acetate and ammonium vanadate. All the synthesized compounds were screened for anticancer activities against T47D and MDA-MB231 cell lines using the MTT assay. However, our obtained results indicated a significant difference between colchicines cytotoxicity and their homologs on treated MDA-MB231 and T47D cells; one compound (4a) showed a significant IC50 on MDA-MB231 cells in cell culture assay.
- Elahian, Fatemeh,Akbari, Morteza,Ghasemi, Maryam,Behtooee, Neda,Taheri, Mohaddeseh,Amini, Mohsen
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p. 840 - 843
(2014/07/21)
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- N-Heterocyclic carbene-catalyzed double acylation of enones with benzils
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Thiazolium carbene-catalyzed reaction of aromatic 1,2-diketones with enones in aprotic solvents gave double acylation products in good yields, whereas hydroacylation products formed by Stetter reaction were not detected at all. These results suggested the generation of aroyloxyenamine species from the 1,2-diketones instead of hydroxyenamines (Breslow intermediates). This journal is
- Takaki, Ken,Ohno, Akira,Hino, Makoto,Shitaoka, Takashi,Komeyama, Kimihiro,Yoshida, Hiroto
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supporting information
p. 12285 - 12288
(2014/12/11)
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- Selective reduction of carbonyl groups in the presence of low-valent titanium reagents
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The chemoselective reduction of several structurally diverse compounds containing carbonyl groups was achieved in the presence of low-valent titanium reagents. This novel synthetic method provides easy access to highly selective reduction of carbonyl groups, and possesses several advantages including one-step procedure, convenient manipulation, good to excellent yields, and short reaction times.
- Lin, Wei,Hu, Ming-Hua,Feng, Xian,Fu, Lei,Cao, Cheng-Pao,Huang, Zhi-Bin,Shi, Da-Qing
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p. 2238 - 2242
(2014/04/17)
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- The catalytic versatility of low toxicity dialkyltriazolium salts: In situ modification facilitates diametrically opposed catalysis modes in one pot
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The ability of triazolium salts to serve as a precatalyst for both an acid and a powerful base/nucleophile (controlled by additives) has been exploited in a process characterised by a unique in situ catalyst modification strategy. The Royal Society of Chemistry 2013.
- Myles, Lauren,Gathergood, Nicholas,Connon, Stephen J.
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supporting information
p. 5316 - 5318
(2013/06/27)
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- An efficient method for selective oxidation of 1,2-diols in water catalyzed by Me2SnCl2
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Dimethyltin(iv)dichloride-catalyzed selective oxidation of 1,2-diols in water was achieved using dibromoisocyanuric acid (DBI) or Br2 as oxidants. The catalyst activates the 1,2-diol moiety through the formation of stannylene acetal in addition to enhancing selectivity. Various cyclic and acyclic 1,2-diol substrates have been selectively oxidized affording α-hydroxyketones in good to excellent yields. This method is safe and simple in operation.
- William, Julius M.,Kuriyama, Masami,Onomura, Osamu
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p. 19247 - 19250
(2013/10/22)
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- A new three-component reaction catalyzed by silica sulfuric acid: Synthesis of tetrasubstituted pyrroles
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A novel, convenient, and efficient three-component reaction of benzoin derivatives, 1,3-dicarbonyls, and ammonium acetate in the presence of silica sulfuric acid (SSA) is described for the synthesis of 2,3,4,5-tetrasubstituted pyrroles under solvent-free
- Tamaddon, Fatemeh,Farahi, Mahnaz
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experimental part
p. 1379 - 1383
(2012/07/28)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Celine,Alexakis, Alexandre
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supporting information
p. 4906 - 4909,4
(2012/12/12)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Céline,Alexakis, Alexandre
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supporting information
p. 4906 - 4909
(2013/01/15)
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- One-pot synthesis of quinoxalines starting from aldehydes under metal-free conditions
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An efficient and convenient synthesis of quinoxalines from easily available aldehydes was performed as a one-pot procedure in good to excellent yields under metal-free conditions, via sequential benzoin condensation, aerobic formation of benzils and condensation of the latter with 1,2-diaminobenzenes.
- Hu, Zhong-Yuan,Du, Ding,Tang, Wei-Fang,Lu, Tao
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experimental part
p. 2262 - 2264
(2012/08/07)
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- N-heterocyclic carbene catalyzed one-pot synthesis of 2,3- diarylquinoxalines
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A one-pot efficient and facile protocol for the direct synthesis of quinoxaline derivatives via tandem N-heterocyclic carbene (NHC)-catalyzed umpolung of aldehydes/oxidation of the benzoins to benzils/condensation of benzils with benzene-1,2-diamines has been developed. Georg Thieme Verlag Stuttgart New York.
- Lin, Yang,Lei, Xiaoli,Yang, Qin,Yuan, Jiangjun,Ding, Qiuping,Xu, Jingshi,Peng, Yiyuan
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supporting information
p. 2699 - 2706
(2012/11/13)
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- One-pot synthesis of polysubstituted imidazoles from arylaldehydes in water catalyzed by nhc using microwave irradiation
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A simple, high yielding synthesis of tri (3a-i) and tetrasubstituted (4a-g) imidazols from aldehydes is described. The cornerstone of this methodology involves the condensation of NH4OAc, substituted aldehydes, and benzoin, which is synthesized in situ from aldehydes catalyzed by N-heterocyclic carbine (NHC), under microwave irradiation in water to afford trisubstituted imidazoles (3a-i). If arylamine is added in the solution, tetrasubstituted imidazoles (4a-g) can be obtained. Lepidilines B and trifenagrel are also synthesized in high yield using this procedure. All the experiment deta are in agreement with the literature.
- Wu, Lei,Jing, Xiaobi,Zhu, Hongxiang,Liu, Yinlin,Yan, Chaoguo
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p. 1204 - 1207
(2013/03/28)
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- An eco-friendly method for synthesis of symmetrical and unsymmetrical benzoin derivatives
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A rapid, highly efficient and mild green synthesis of symmetrical and unsymmetrical benzoin derivatives was achieved from the reaction of benzaldehyde derivatives with potassium cyanide in dimethyl sulfoxide under argon gas and ultrasound. This simple method affords benzoin derivatives at room temperature in short reaction times with high yield and purity.
- Safari, Javad,Arani, Naimeh Moshtael,Isfahani, Anousheh Ramezan
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experimental part
p. 495 - 498
(2011/12/21)
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- Amine-linked N-heterocyclic carbenes: The importance of an pendant free-amine auxiliary in assisting the catalytic reaction
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We have successfully expanded the library of amino-NHCs with varying substituents on the amine group, leading to insight about the instability of NHCs arising from the intermolecular interaction of the dangling amine side-arm. However, the pendant amine plays an important role with respect to the catalytic process, resuscitating the catalytic activity of unsaturated NHC's through a synergistic effect invoked by the secondary amine. This proof of concept allows us to expand the spectrum of catalysis to C-C, as well as C-B bond formation. Copyright
- Li, Chia-Yi,Kuo, Yi-Yin,Tsai, Jie-Hong,Yap, Glenn P. A.,Ong, Tiow-Gan
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supporting information
p. 1520 - 1524
(2013/01/11)
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- Polarity reversal induced by electrochemically generated thiazol-2-ylidenes: The Stetter reaction
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The inversion of the normal reactivity (umpolung) of aldehydes has been induced via N-heterocyclic carbenes (NHCs) thiazol-2-ylidenes 2a or 3a, generated by simple electrolyses of solutions containing thiazolium salt 2 or 3. Accordingly, 1,4-dicarbonyl compounds have been obtained, in mild conditions and in moderate to very high yields, via 1,4-addition of the Breslow intermediates to the suitable Michael acceptor. The procedure has been performed in classical organic solvents (VOCs) as well as in room temperature ionic liquids (RTILs). The different reactivity of aliphatic aldehydes vs the one of aromatic and heteroaromatic aldehydes has been emphasized.
- Orsini, Monica,Chiarotto, Isabella,Sotgiu, Giovanni,Inesi, Achille
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experimental part
p. 3511 - 3517
(2010/07/09)
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- Facile route to benzils from aldehydes via NHC-catalyzed benzoin condensation under metal-free conditions
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A simple and efficient one-pot procedure for the synthesis of α-diketones from aldehydes via benzoin condensation under the influence of a catalytic amount of azolium salt combined with DBU has been developed. Thus, aldehyde was allowed to react with the azolium salt/DBU catalytic system at room temperature, and then the reaction mixture was heated to 70 °C under air atmosphere to afford the corresponding 1,2-diketone in good yield. This would be an efficient alternative method of synthesizing α-diketones from aldehydes under metal-free conditions. Crown Copyright
- Shimakawa, Yuuki,Morikawa, Takashi,Sakaguchi, Satoshi
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supporting information; experimental part
p. 1786 - 1789
(2010/05/19)
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- Study on the reactivity of aldehydes in electrolyzed ionic liquids: Benzoin condensation - Volatile organic compounds (VOCs) vs. room temperature ionic liquids (RTILs)
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The benzoin condensation of aromatic and heteroaromatic aldehydes, catalyzed by electrochemically generated N-heterocyclic carbenes, has been set up in the absence of organic solvents and bases. α-Hydroxy ketones have been isolated in good to elevated yields, in short reaction times. Aldol products and carbene-aldehyde adducts have been obtained in elevated yields from linear and short branched aldehydes, respectively. A comparison with the use of classical organic solvents has been reported Copyright
- Chiarotto,Feroci,Orsini,Feeney,Inesi
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supporting information; experimental part
p. 3287 - 3292
(2011/02/23)
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- An investigation of the catalytic potential of mono- and dicationic imidazolium N-heterocyclic carbenes in the benzoin condensation
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The catalytic potential of imidazolium salts in the benzoin condensation was investigated. Various aromatic aldehydes were tested in the benzoin condensation under the optimised protocol to afford α-hydroxyketones using N-heterocyclic carbenes derived from mono- and dicationic imidazolium salts. The products were obtained in good yields within short reaction times. Dicationic imidazolium salts with a long aliphatic chain between the imidazole rings were found to be more effective pre-catalysts for the benzoin condensation in comparison to the corresponding monocationic salts having the same aliphatic chain length.
- Mavis, Murat Emrah,Yolacan, Cigdem,Aydogan, Feray
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experimental part
p. 4509 - 4511
(2010/09/18)
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- Synthesis of imidazolium and pyridinium-based ionic liquids and application of 1-alkyl-3-methylimidazolium salts as pre-catalysts for the benzoin condensation using solvent-free and microwave activation
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An efficient one-pot procedure for the synthesis of ionic liquids based on nitrogen-containing heterocycles, imidazolium or pyridinium under 'green chemistry' conditions has been described. Imidazolium salts and DBU have been found to catalyze efficiently the benzoin condensation giving good yields within very short reaction time using solvent-free microwave activation conditions.
- Aupoix, Audrey,Pégot, Bruce,Vo-Thanh, Giang
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experimental part
p. 1352 - 1356
(2010/04/02)
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- Methylene-bridged bis(benzimidazolium) salt as a highly efficient catalyst for the benzoin reaction in aqueous media
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Benzoin reactions are catalyzed effectively by a methylene-bridged bis(benzimidazolium) salt to yield α-hydroxy ketones, and the reactions proceed in water as the aqueous medium under mild conditions. The Royal Society of Chemistry.
- Iwamoto, Ken-Ichi,Kimura, Hitomi,Oike, Masaaki,Sato, Masayuki
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experimental part
p. 912 - 915
(2008/10/09)
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- A ceric ammonium nitrate N-dearylation of N-p-anisylazoles applied to pyrazole, triazole, tetrazole, and pentazole rings: Release of parent azoles. Generation of unstable pentazole, HN5/N5-, in solution
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(Chemical Equation Presented) The reaction of cerium(IV) ammonium nitrate (CAN) with a range of N-(p-anisyl)azoles in acetonitrile or methanol solvents leads to N-dearylation releasing the parent NH-azole and p-benzoquinone in comparable yields. The scope and limitations of the reaction are explored. It was successful with 1-(p-anisyl)pyrazoles, 2-(p-anisyl)-1,2,3-triazoles, 2-(p-anisyl)-2H-tetrazoles, and 1-(p-anisyl)pentazole. The dearylation renders the p-anisyl group as a potentially useful N-protecting group in azole chemistry. The azole released in solution from 1-(p-anisyl)pentazole is unstable HN5, the long-sought parent pentazolic acid. p-Anisylpentazole samples were synthesized with combinations of one, two, and three 15N atoms at all positions of the pentazole ring. The unstable HN 5/N5- produced at -40°C did not build up in the solution but degraded to azide ion and nitrogen gas with a short lifetime. The 15N-labeling of the N3- ion obtained from all samples proved unequivocally that it came from the degradation of HN 5 (tautomeric forms) and/or its anion N5- in the solution.
- Butler, Richard N.,Hanniffy, John M.,Stephens, John C.,Burke, Luke A.
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p. 1354 - 1364
(2008/04/12)
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- Thiazolium salt immobilized on ionic liquid: An efficient catalyst and solvent for preparation of α-hydroxyketones
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Aldehydes were efficiently converted to acyloins and benzoins using a new ionic liquid, 3-[2-(1-butyl-1H-imidazol-1,3-ium-3-yl)ethyl]-4,5-dimethyl-1,3- thiazol-3-ium dibromide 1. This ionic liquid is introduced as a catalyst and a solvent. Acyloins and benzoins were easily isolated from the reaction mixture via simple extraction, and the ionic liquid could be recycled for further use. Also, -hydroxy ketones with an aromatic and aliphatic substituent were prepared starting from aromatic and aliphatic aldehydes in the presence of ionic liquid 1.
- Mohanazadeh, Farajollah,Aghvami, Majid
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p. 2467 - 2475
(2008/02/10)
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- A reductase-mimicking thiourea organocatalyst incorporating a covalently bound NADH analogue: Efficient 1,2-diketone reduction with in situ prosthetic group generation and recycling
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A new class of bifunctional organocatalyst promotes the chemoselective reduction of diketone electrophiles at catalytic loadings in the presence of an inorganic co-reductant. The Royal Society of Chemistry.
- Procuranti, Barbara,Connon, Stephen J.
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p. 1421 - 1423
(2008/02/03)
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- Benzoin reaction in water as an aqueous medium catalyzed by benzimidazolium salt
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Benzoin reactions are catalyzed by N,N-dialkylbenzimidazole to yield α-hydroxy ketones; the reaction proceeds in water as an aqueous medium under mild conditions. The utility of these salts as pre-catalysts in these reactions has been demonstrated.
- Iwamoto, Ken-ichi,Hamaya, Masako,Hashimoto, Naoki,Kimura, Hitomi,Suzuki, Yumiko,Sato, Masayuki
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p. 7175 - 7177
(2007/10/03)
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- Microwave assisted benzoin condensation using thiamine as catalyst
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α-Hydroxyketones were prepared in appreciable yields at a very high speed, (by the benzoin condensation) under microwave irradiation using a catalytic amount of thiamine hydrochloride, from various aromatic as well as heteroaromatic aldehydes. They can be used as intermediates in NCE synthesis.
- Bag, Seema,Vaze, Vidula V.,Degani, Mariam S.
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p. 267 - 269
(2007/10/03)
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- One-step assembly of functionalized γ-butyrolactones from benzoins or benzaldehydes via an N-heterocyclic carbene-mediated tandem reaction
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(Chemical Equation Presented) We describe here a direct, efficient, one-step construction of γ,γ-difunctionalized γ-butyrolactones from benzoins or benzaldehydes via a tandem reaction promoted by 1,3-dimethyl imidazolin-2-ylidene, an N-heterocyclic carbene (NHC).
- Ye, Wei,Cai, Guanliang,Zhuang, Zeyang,Jia, Xueshun,Zhai, Hongbin
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p. 3769 - 3771
(2007/10/03)
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- Samarium reagent-promoted formation of benzoins from diarylmethanones and DMF via a carbene rearrangement reaction
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Prompted by samarium metal in DMF with TMSCl or iodine as an activator, or by SmI2/THF system, diarylmethanones react readily with DMF to afford benzoins in moderate to good yields via rearrangement of aryl groups. As for asymmetric diarylmethanones, products resulting from the migration of either aryl group were obtained, where the migration of aryl groups shows certain priority.
- Liu, Yongjun,Xu, Xiaoliang,Zhang, Yongmin
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p. 4867 - 4873
(2007/10/03)
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- Direct Formation of Benzoins from Diarylmethanones via a Rearrangement Reaction Promoted by Samarium Metal in DMF
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Diarylmethanones react readily with DMF when promoted by samarium metal in DMF with TMSCl or iodine as an activator, to afford benzoins in good to excellent yields via rearrangement of aryl groups. As for asymmetric diarylmethanones, products resulting from the migration of either aryl group were obtained, where the migration of aryl groups shows certain priority.
- Liu, Yongjun,Xu, Xiaoliang,Zhang, Yongmin
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p. 445 - 448
(2007/10/03)
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