- 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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Read Online
- Benzoin Radicals as Reducing Agent for Synthesizing Ultrathin Copper Nanowires
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In this work, we report a new, general synthetic approach that uses heat driven benzoin radicals to grow ultrathin copper nanowires with tunable diameters. This is the first time carbon organic radicals have been used as a reducing agent in metal nanowire synthesis. In-situ temperature dependent electron paramagnetic resonance (EPR) spectroscopic studies show that the active reducing agent is the free radicals produced by benzoins under elevated temperature. Furthermore, the reducing power of benzoin can be readily tuned by symmetrically decorating functional groups on the two benzene rings. When the aromatic rings are modified with electron donating (withdrawing) groups, the reducing power is promoted (suppressed). The controllable reactivity gives the carbon organic radical great potential as a versatile reducing agent that can be generalized in other metallic nanowire syntheses.
- Cui, Fan,Dou, Letian,Yang, Qin,Yu, Yi,Niu, Zhiqiang,Sun, Yuchun,Liu, Hao,Dehestani, Ahmad,Schierle-Arndt, Kerstin,Yang, Peidong
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Read Online
- Synthesis of thiazolium salts and their screening for catalytic activity
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A facile synthetic method to prepare thiazolium-based ionic liquids in high yield was developed. The direct alkylation of thiazole was performed using a trialkyl orthoester as both the alkyl donor and the solvent. The synthesized thiazolium salts were sub
- Lee, Seul Ki,Kim, Do Joong,Park, Jin Kyoon
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Read Online
- 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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- 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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- Development of Imidazoline-2-one Derivatives as Potential Antifungal and Anthelminthic Agents: in silico and in vitro Evaluation
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Based on appropriate values of synthetic accessibility concerning from ADMET properties and docking scores by docking against proteins 3OZU and 1OJ0, a series of 4,5-diphenyl-1H-imidazol-2-ones (I1?15) were synthesized. The key intermediate, 2-hydroxy-1,2-disubstitutedethanones (E1?15) were prepared by benzoin condensation using 2:1 ratio of aromatic aldehydes and thiamine in the presence of alkali. Further, these cyclized ethanones (E1?15) were treated with urea to yield 4,5-diphenyl-1H-imidazol-2-one derivatives (I1?15) and were characterized by IR,1H NMR, Mass spectra, and CHNO analysis. The synthesized compounds were screened for their anthelmintic potential on Pheretima Posthuma along with standard albendazole, and antifungal activity (minimum inhibitory concentration method) on Candida albicans and Aspergillus niger along with standard miconazole. The results revealed that among all the tested compounds I3, I4, and I7 show considerable synthetic accessibility, docking scores, anthelminthic, and antifungal activity.
- Chilamakuru, Naresh Babu,Mallela, Vijaya Jyothi,Peraman, Ramalingam,Shaik, Shakir Basha,Simham, Venu,Singirisetty, Triveni
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p. 423 - 433
(2021/11/24)
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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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- 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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- 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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- 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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- 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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- Efficient Green Synthesis and Computational Chemical Study of Some Interesting Heterocyclic Derivatives as Insecticidal Agents
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A series of 5,5-diarylhydantoin (Dilantin) 3, 4, and 7, imidazole 1, 2, 5, 6, 8, and 9, thiazole 10–12, triazinthione 13, 15, 16, and 17, and thiadiazine 14 derivatives, containing diverse hydrophobic groups, were green synthesized through one-pot stepwise reaction of aromatic aldehydes, vitamin B1, and nitrogen nucleophiles, for example, urea, thiourea, and thiosemicarbazide using grinding technique as well as conventional thermal methods. Such synthesized compounds have potent insecticidal activities; for example, compounds 4, 6, and 17 exhibited the highest insecticidal activity against both Plutella xylostella and Helicoverpa armigera with minimum inhibitory concentration values at 500?μg/mL and LD50 activities at 50?μg/mL. The density functional theory was then applied to explore the structural and electronic characteristics of these compounds. All the synthesized compounds have been characterized based on their elemental analyses and spectral data.
- Fahmy,Rizk,Hemdan,El-Sayed,Hassaballah
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p. 2545 - 2555
(2018/09/27)
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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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- Self-supported N-heterocyclic carbenes and their use as organocatalysts
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The study of N-heterocyclic carbenes (NHCs) as organocatalysts has proliferated in recent years, and they have been found to be useful in a variety of reactions. In an attempt to further expand their utility and to study their recyclability, we designed and synthesized a series of self-supported NHCs in which the catalytic carbene groups form part of a densely functionalized polymer backbone, and studied them as organocatalysts. Of the self-Supported NHCs examined, a benzimidazole derived polymer with flexible linkers connecting the catalytic groups was found to be the most efficient organocatalyst in a model benzoin condensation reaction, and thus it was used in a variety of such reactions, including some involving catalyst recycling. Furthermore, it was also used to catalyze a set of redox esterification reactions involving conjugated unsaturated aldehydes. In all of these reactions the catalyst afforded good yield of the desired product and its polymeric nature facilitated product purification.
- Ma, Shuang,Toy, Patrick H.
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- Catalytically active lead(II)-imidazolium coordination assemblies with diversified lead(II) coordination geometries
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Five Pb(ii)-imidazolium carboxylate coordination assemblies with novel structural motifs were derived from the reaction between the corresponding flexible, semi flexible or rigid imidazolium carboxylic acid ligands and lead nitrate. The imidazolium linker present in these molecules likely plays a triple role such as the counter ion to balance the metal charge, the ligand being an integral part of the final product and the catalyst facilitating carbon-carbon bond formation reaction. These lead-imidazolium coordination assemblies exhibit, variable chemical and thermal stabilities, as well as catalytic activity. These newly prepared catalysts are highly active towards benzoin condensation reactions with good functional group tolerance.
- Naga Babu, Chatla,Suresh, Paladugu,Srinivas, Katam,Sathyanarayana, Arruri,Sampath, Natarajan,Prabusankar, Ganesan
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supporting information
p. 8164 - 8173
(2016/06/06)
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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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- (±)Methanodibenzodiazocine tethered [C-H]δ+ functional site: Study towards benzoin condensation and Baylis-Hillman reactions
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Abstract New heterocyclic ring systems consisting of (±) methanodibenzodiazocine and imidazolium/ benzimidazolium salts were synthesized in very good yield. Subsequently, these halide salts were subjected to the anion exchange reaction with KPF6 to yield the corresponding azolium salts in excellent yield. The possible applications of these newly prepared salts were investigated in homogeneous catalysis. Remarkable changes in the catalytic activity were observed by varying the bulkiness of N-substituent at imidazole. Catalytic activity of these newly prepared salts was tested for the benzoin condensation reaction. Exclusive formation of benzoin products were observed in good yield. Similarly, the dimerization of cyclohexen-1-one to Baylis-Hillman type product, 2-(3-oxocyclohexyl)-2-cyclohexen-1-one was studied. [Figure not available: see fulltext.]
- Sathyanarayana, Arruri,Prabusankar, Ganesan
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p. 821 - 831
(2015/08/06)
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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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- 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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- N-Heterocyclic Carbene Catalyzed Highly Chemoselective Intermolecular Crossed Acyloin Condensation of Aromatic Aldehydes with Trifluoroacetaldehyde Ethyl Hemiacetal
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A highly chemoselective intermolecular crossed acyloin condensation between aromatic aldehydes and trifluoroacetaldehyde ethyl hemiacetal has been developed under mild reaction conditions using N-heterocyclic carbene as a catalyst. A wide range of aromatic aldehydes bearing electron-withdrawing and -donating substituents underwent a smooth transformation to their corresponding trifluoromethyl containing acyloin derivatives in moderate to good yields. (Figure Presented).
- Ramanjaneyulu, Bandaru T.,Mahesh, Sriram,Vijaya Anand, Ramasamy
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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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- 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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- NHC-initiated cascade, metal-free synthesis of quinoxaline derivatives under solvent-free conditions
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2,3-Diaryl quinoxaline derivatives have been efficiently synthesized by cascade, metal-free, and solvent-free reaction of aryl aldehydes with aryl 1,2-diamines initiated by N-heterocyclic carbene. Compared with reported methods, this procedure has the advantages of easy work-up, reduced energy consumption, and elimination of solvent waste, hazards, and toxicity. A group of potentially bioactive compounds has been prepared for biomedical screening.
- Gao, Lijiu,Liu, Rui,Yu, Chenxia,Yao, Changsheng,Li, Tuanjie,Xiao, Zhaoxin
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p. 2131 - 2138
(2014/05/06)
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- Design, synthesis and biological evaluation of 2, 4, 5-triphenylimidazole derivatives with preliminary SAR
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A series of N1-substituted 2,4,5-triphenyl imidazole derivatives was designed, synthesized and evaluated for their p53-MDM2 binding inhibitory activities and anti-proliferative activities in vitro against four human cancer cell lines (PC3, KB, A549 and HCT116). Although logical evaluation revealed weak p53-MDM2 binding inhibitory activities, most of the obtained molecules displayed moderate to potent cytotoxicities against tested cell lines. As a potential lead compound for further optimization, compound 9c was evaluated as the most potent compound against four cell lines and could induce cell cycle arrest at G2/M phase. The binding mode of compound 9f and MDM2 was further studied by docking analysis and the unexpected interaction mode revealed that this series of compounds may take part into a different binding modes as the lead compound Such as Nutlin, which could induce a different mechanism in cancer therapy.
- Hu, Chunqi,Shen, Jianfeng,Bian, Kejun,Zhang, Ruoyu,Deng, Liping
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p. 762 - 769
(2014/07/07)
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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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- 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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- 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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- 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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- Chemoselective and repetitive intermolecular cross-acyloin condensation reactions between a variety of aromatic and aliphatic aldehydes using a robust N-heterocyclic carbene catalyst
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We found that chemoselectivity of the crossed acyloin product is controlled by the adjustment of the aromatic aldehyde/aliphatic aldehyde ratio. Moreover, we observed the persistent catalytic activity of the homogeneous NHC catalyst in a solution due to N
- Jin, Ming Yu,Kim, Sun Min,Mao, Hui,Ryu, Do Hyun,Song, Choong Eui,Yang, Jung Woon
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supporting information
p. 1547 - 1550
(2014/03/21)
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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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- NHC-catalyzed hydroacylation of styrenes
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New hydroacylation catalysts: Highly electron-rich N-heterocyclic carbenes (NHCs) facilitate the intermolecular hydroacylation of unstrained olefins. This unprecedented organocatalytic coupling joins simple and abundant aldehydes and styrenes to yield valuable ketone products. EWG=electron-withdrawing group, EDG=electron-donating group. Copyright
- Schedler, Michael,Wang, Duo-Sheng,Glorius, Frank
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supporting information
p. 2585 - 2589
(2013/04/10)
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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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- Synthesis and SAR study of 4,5-diaryl-1H-imidazole-2(3H)-thione derivatives, as potent 15-lipoxygenase inhibitors
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A series of 4,5-diaryl-1H-imidazole-2(3H)-thione was synthesized and their inhibitory potency against soybean 15-lipoxygenase and free radical scavenging activities were determined. Compound 11 showed the best IC50 for 15-LOX inhibition (IC50 = 4.7 μM) and free radical scavenging activity (IC50 = 14 μM). Methylation of SH at C2 position of imidazole has dramatically decreased the 15-LOX inhibition and radical scavenging activity as it can be observed in the inactive compound 14 (IC50 >250 μM). Structure activity similarity (SAS) showed that the most important chemical modification in this series was methylation of SH group and Docking studies revealed a proper orientation for SH group towards Fe core of the 15-LOX active site. Therefore it was concluded that iron chelating could be a possible mechanism for enzyme inhibition in this series of compounds.
- Assadieskandar, Amir,Amini, Mohsen,Salehi, Marjan,Sadeghian, Hamid,Alimardani, Maliheh,Sakhteman, Amirhossein,Nadri, Hamid,Shafiee, Abbas
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p. 7160 - 7166
(2013/01/15)
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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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- Highly enantioselective intermolecular stetter reaction of simple acrylates: Synthesis of α-chiral γ-Ketoesters
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Simple Stetter: A novel N-heterocyclic carbene (NHC) was designed by combining an electron-rich 2,6-dimethoxy substituent and an underestimated yet promising chiral motif. With this NHC in hand, a highly enantioselective intermolecular Stetter reaction of simple acrylates was developed, yielding versatile α-chiral γ-ketoesters. This represents the first catalytic asymmetric route towards these valuable compounds (see scheme).
- Wurz, Nathalie E.,Daniliuc, Constantin G.,Glorius, Frank
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supporting information
p. 16297 - 16301
(2013/02/22)
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- Efficient synthesis of γ-keto sulfones by NHC-catalyzed intermolecular Stetter reaction
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The N-heterocyclic carbene-catalyzed intermolecular Stetter reaction of aldehydes with α,β-unsaturated sulfones allows the atom-economic and selective formation of γ-keto sulfones in good yields. Key to the success of this unique transition-metal-free carbon-carbon bond-forming reaction is the right choice of the NHC precursor and base. The reaction tolerates a broad range of different aldehydes.
- Bhunia, Anup,Yetra, Santhivardhana Reddy,Bhojgude, Sachin Suresh,Biju, Akkattu T.
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supporting information; experimental part
p. 2830 - 2833
(2012/07/17)
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- Visible light mediated homo- and heterocoupling of benzyl alcohols and benzyl amines on polycrystalline cadmium sulfide
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The oxidative coupling of sp3 hybridized carbon atoms by photocatalysis is a valuable synthetic method as stoichiometric oxidation reagents can be avoided and dihydrogen is the only byproduct of the reaction. Cadmium sulfide, a readily available semiconductor, was used as a visible light heterogeneous photocatalyst for the oxidative coupling of benzyl alcohols and benzyl amines by irradiation with blue light. Depending on the structure of the starting material, good to excellent yields of homocoupling products were obtained as mixtures of diastereomers. Cross-coupling between benzyl alcohols and benzyl amines gave product mixtures, but was selective for the coupling of tetrahydroisoquinolines to nitromethane. The results demonstrate that CdS is a suitable visible light photocatalyst for oxidative bond formation under anaerobic conditions.
- Mitkina, Tatiana,Stanglmair, Christoph,Setzer, Wolfgang,Gruber, Michael,Kisch, Horst,Koenig, Burkhard
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supporting information; experimental part
p. 3556 - 3561
(2012/06/01)
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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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- A family of thiazolium salt derived N-heterocyclic carbenes (NHCs) for organocatalysis: Synthesis, investigation and application in cross-benzoin condensation
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A family of thiazolium salt derived N-heterocyclic carbenes (NHCs) bearing sterically demanding aryl substituents on the nitrogen and with varying backbone substitution patterns have been synthesized. Investigation of the catalytic activity of these NHCs in a number of benzoin-type coupling reactions revealed markedly different levels of reactivity and selectivity. To elucidate the underlying factors leading to differences in reactivity, a study of the electronic and steric properties of these NHC catalysts was conducted. By using the best catalyst in this study, the intermolecular cross-benzoin condensation reaction was explored in more detail.
- Piel, Isabel,Pawelczyk, Marius D.,Hirano, Keiichi,Froehlich, Roland,Glorius, Frank
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supporting information; scheme or table
p. 5475 - 5484
(2011/11/29)
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- Enantioselective aerobic oxidation of α-hydroxy-ketones catalyzed by oxidovanadium(V) methoxides bearing chiral, N-salicylidene- tert -butylglycinates
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Chiral oxidovanadium(V) methoxides prepared from 3,5-disubstituted-N- salicylidene-l-tert-butylglycines and vanadyl sulfate in air-saturated MeOH serve as highly enantioselective catalysts for asymmetric aerobic oxidations and kinetic resolution of alkyl, aryl, and heteroaryl α-hydroxy-ketones with differed α-substituents at ambient temperature in toluene or TBME (tert-butyl methyl ether). The best scenarios involve the use of complexes which bear the tridendate templates derived from 3,5-diphenyl- or 3-o-biphenyl-5-nitro-salicyaldehyde. The kinetic resolution selectivities of the aerobic oxidation process are in the range of 12 to >1000 based on the selectivity factors (krel).
- Chen, Chien-Tien,Kao, Jun-Qi,Salunke, Santosh B.,Lin, Ya-Hui
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supporting information; experimental part
p. 26 - 29
(2011/03/22)
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- NHC triggered cascade metal-free synthesis of 2,3-diarylated indoles under solvent-free conditions
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A new cascade strategy to the synthesis of 2,3-diarylated indoles via the metal-free reaction of aryl aldehyde and aryl amine triggered by N-heterocyclic carbene (NHC) under solvent-free conditions, has been disclosed. The protocol has the advantages of easy work-up, high yields, wide application scope, and an environmentally benign procedure compared with the reported methods.
- Yao, Changsheng,Wang, Donglin,Lu, Jun,Qin, Bingbin,Zhang, Honghong,Li, Tuanjie,Yu, Chenxia
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supporting information; experimental part
p. 6162 - 6165
(2011/11/30)
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- Designing N-heterocyclic carbenes: Simultaneous enhancement of reactivity and enantioselectivity in the asymmetric hydroacylation of cyclopropenes
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Faster, higher, stronger! The N-heterocyclic carbene (NHC) catalyzed diastereo- and enantioselective hydroacylation of cyclopropenes affords structurally valuable acylcyclopropanes. A new family of electron-rich, 2,6-dimethoxyphenyl-substituted NHCs induc
- Liu, Fan,Bugaut, Xavier,Schedler, Michael,Froehlich, Roland,Glorius, Frank
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supporting information; experimental part
p. 12626 - 12630
(2012/02/15)
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