- 2-(Diethylamino)ethanethiol, a new reagent for the odorless deprotection of aromatic methyl ethers
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A new reagent for the deprotection of aromatic methyl ethers, 2-(diethylamino)ethanethiol, is reported. This compound, commercially available as its HCl salt, affords the corresponding phenols in good to excellent yields on a wide variety of substrates. A clear advantage of this method over the use of more common thiols, such as ethanethiol, is the easy extraction of both the deprotecting reagent and the byproduct 2-(diethylamino)ethyl methyl sulfide into the aqueous phase by quenching with dilute acid, which allows an essentially odorless workup.
- Magano, Javier,Chen, Michael H.,Clark, Jerry D.,Nussbaumer, Thomas
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Read Online
- Quantitative model of the enhancement of peroxidase-induced luminol luminescence
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Many phenolic compounds are known to enhance the chemiluminescence associated with the horseradish peroxidase-catalyzed oxidation of luminol, but the mechanism of enhancement is still unproved. Using stopped-flow spectrophotometry, we have found that a series of luminescence enhancers react rapidly with the peroxidase reactive intermediates (compound I and compound II) supporting the hypothesis that the enhancement is due to the acceleration of the enzyme turnover. In addition, pulse radiolysis experiments have shown that the enhancers' phenoxyl radicals oxidize luminol, consistent with a redox mediator role for the enhancers. The latter reaction was found to be reversible, showing that enhancers of low reduction potential, which are efficient in accelerating the enzyme turnover, are also scavengers of luminol radicals and therefore luminescence quenchers. Using these data, a simple model is proposed which correctly predicts that the efficiency of a phenolic compound as luminescence enhancer depends on the reduction potential of the respective phenoxyl radical according to a bell-shaped function with a maximum at ~0.8 V.
- Easton, Patricia M.,Simmonds, Adrian C.,Rakishev, Askar,Egorov, Alexey M.,Candeias, Luis P.
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Read Online
- Preparation method 4 - (imidazol -1 -yl) phenol
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The invention discloses a preparation method of 4 - (imidazol -1 -yl) phenol, and belongs to the field of in-vitro diagnosis. The catalyst is prepared by taking bromoanisole and imidazole as raw materials. The organic phase is extracted with saturated bri
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Paragraph 0035; 0037-0040; 0042-0043; 0045-0046; 0048-0050
(2021/10/20)
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- Practical and Efficient Synthesis of 2-Thio-imidazole Derivative - ZY12201: A Potent TGR5 Agonist
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Early scalable process development for the synthesis of ZY12201, a novel TGR5 receptor agonist, as a potential clinical candidate is described. A practical, efficient, and scalable synthetic route provided ZY12201 in seven steps and 32% overall yield. The
- Agarwal, Sameer,Chaubey, Vipin,Chauhan, Rakesh,Jain, Sarika,Joshi, Vivek M.,Mande, Hemant,Pamidimukkala, Padmaja Sudhakar,Pandey, Bipin,Sasane, Santosh,Shah, Kalpesh,Shah, Shailesh R.,Shukla, Mrigendra,Singh, Kumar K.,Sojitra, Chandrakant,Soman, Shubhangi
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p. 1508 - 1514
(2020/11/23)
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- Three-Component, Interrupted Radical Heck/Allylic Substitution Cascade Involving Unactivated Alkyl Bromides
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Developing efficient and selective strategies to approach complex architectures containing (multi)stereogenic centers has been a long-standing synthetic challenge in both academia and industry. Catalytic cascade reactions represent a powerful means of rapidly leveraging molecular complexity from simple feedstocks. Unfortunately, carrying out cascade Heck-type reactions involving unactivated (tertiary) alkyl halides remains an unmet challenge owing to unavoidable β-hydride elimination. Herein, we show that a modular, practical, and general palladium-catalyzed, radical three-component coupling can indeed overcome the aforementioned limitations through an interrupted Heck/allylic substitution sequence mediated by visible light. Selective 1,4-difunctionalization of unactivated 1,3-dienes, such as butadiene, has been achieved by employing different commercially available nitrogen-, oxygen-, sulfur-, or carbon-based nucleophiles and unactivated alkyl bromides (>130 examples, mostly >95:5 E/Z, >20:1 rr). Sequential C(sp3)-C(sp3) and C-X (N, O, S) bonds have been constructed efficiently with a broad scope and high functional group tolerance. The flexibility and versatility of the strategy have been illustrated in a gram-scale reaction and streamlined syntheses of complex ether, sulfone, and tertiary amine products, some of which would be difficult to access via currently established methods.
- Bellotti, Peter,Glorius, Frank,Heidrich, Bastian,Huang, Huan-Ming,Pflüger, Philipp M.,Schwarz, J. Luca
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supporting information
p. 10173 - 10183
(2020/06/27)
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- High-performance sono/nano-catalytic system: CTSN/Fe3O4-Cu nanocomposite, a promising heterogeneous catalyst for the synthesis of: N -arylimidazoles
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Herein, a promising heterogeneous nanoscale catalytic system constructed of chitosan (CTSN, as a polymeric basis), iron oxide nanoparticles (Fe3O4 NPs, as the magnetic agent), and copper oxide nanoparticles (CuO NPs, as the main cata
- Taheri-Ledari, Reza,Hashemi, Seyed Masoud,Maleki, Ali
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p. 40348 - 40356
(2019/12/25)
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- Chan-Lam cross-coupling reaction based on the Cu2S/TMEDA system
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A catalyst based on the readily available Cu2S/TMEDA system using a stable copper(I) source was developed for the Chan-Lam cross-coupling reaction. The capability of the catalyst was demonstrated with 1H-benzo[d]imidazol-2(3H)-one, 1H-benzo[d]imidazole, and 1H-imidazole together with electron-deficient, electron-rich, and sterically demanding boronic acids at room temperature in the presence of atmospheric oxygen to give the cross-coupling products in moderate to excellent yields. In addition, the coupling reaction of 1H-benzo[d]imidazole with several pinacol or neopentylglycol boronates indicated further potential of the catalyst. The reaction conditions tolerate the hydroxyl and bromo functional groups. The catalytic system also enables to synthesize the mono-N-substituted anilines from primary aliphatic amines. However, the two model compounds for the secondary and aromatic amines, piperidine and aniline, do not react. Two sterically demanding products with the restricted C–N bond rotation, synthesized by the N-arylation of 1H-benzo[d]imidazol-2(3H)-one with o-tolylboronic acid, enabled to confirm the atropisomers prepared by the Chan-Lam cross-coupling reaction. Furthermore, an example of one-pot Chan-Lam and Suzuki-Miyaura reaction has been reported.
- Janíková, Kate?ina,Jedinák, Luká?,Volná, Tereza,Canka?, Petr
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p. 606 - 617
(2018/01/01)
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- Functional 1,8-naphthyridine copper(I) complex as efficient catalyst for n-arylation of imidazoles coupling reactions
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The functional 1,8-naphthyridine copper(I) complex, synthesized through a non-catalyst C(sp3)-H methylenation, catalyzes the cross-coupling reaction of aryl halides with imidazoles, by C?N bond formation. The Cu(I) complex catalyzes the reaction with a low catalyst loading (1%, molar fraction) and cheap base even under aerobic conditions. The procedure tolerates aryl halides with various functional groups (such as methyl, methoxy, acetyl, fluoro, nitrile and nitro groups) and gives the corresponding coupling products in moderate to high yields.
- Gou, Gao-Zhang,Wu, Na,Zhang, Ju-Cheng,Shi, Ling,Liu, Gui-Yang,Liu, Wei,Mang, Chao-Yong,Chi, Shao-Ming
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p. 181 - 185
(2018/02/28)
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- Copper(I) Oxide/N,N′-Bis[(2-furyl)methyl]oxalamide-Catalyzed Coupling of (Hetero)aryl Halides and Nitrogen Heterocycles at Low Catalytic Loading
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An easily prepared oxalic diamide is a powerful ligand for the copper-catalyzed coupling of aryl halides with nitrogen heterocycles. Only 1–2 mol% each of copper(I) oxide and N,N′-bis[(2-furyl)methyl]oxalamide (BFMO) are needed to form N-arylation products under mild conditions. More than 10 different types of nitrogen heterocycles are compatible with these conditions, thereby giving the corresponding N-arylation products. (Figure presented.).
- Pawar, Govind Goroba,Wu, Haibo,De, Subhadip,Ma, Dawei
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supporting information
p. 1631 - 1636
(2017/05/22)
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- N-terminal strategy (N1-N4) toward high performance liquid crystal materials
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Liquid crystal materials have a variety of applications in many fields such as display techniques as well as photonics and optics. However, only few design principles have been disclosed on liquid crystal materials with different N-heterocycles as the terminal groups, which hinder the development of the heterocyclic liquid crystals. Here, a strategy of molecular design for N-heterocyclic liquid crystal materials is reported. On the basis of this strategy, a series of convenient N-heterocycles such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, 1,2,3,4-tetrazole were applied to synthesize the novel liquid crystals. Most of them have proved to exhibit good mesomorphic behaviors which make them excellent components in the mixture of the LCDs materials. The simple attachment of N-heterocyclic units to the liquid crystal molecules through a mild reaction condition will provide a good prospect for the design of N-heterocyclic liquid crystals.
- Hong, Fengying,Xia, Zhengce,Zhu, Dezhao,Wu, Hongxiang,Liu, Jianhui,Zeng, Zhuo
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supporting information
p. 1285 - 1292
(2017/02/15)
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- Cu2O/nano-CuFe2O4: An efficient and magnetically recoverable catalyst for the ligand-free N-arylation of amines and nitrogen heterocycles with aryl halides
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An efficient strategy has been developed for the N-arylation of azoles and aliphatic amines with aryl halide using a Cu2O/nano-CuFe2O4 magnetic composite as the catalyst and KOH as the base. The methodology is found to be applicable to a variety of nitrogen-containing heterocycles, such as imidazole, indole, and pyrrole, as well as aliphatic amines in high yields with practical simplicity under cost-effective "ligand-free" conditions. The magnetic property of the catalyst allowed its fast separation from the reaction medium by an external magnet. Additionally, the inexpensive catalyst could be recycled for five consecutive runs with small drops in catalytic activity.
- Elhampour, Ali,Nemati, Firouzeh,Kaveh, Mahdieh
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supporting information
p. 223 - 225
(2016/03/01)
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- Nano-magnetic Fe3O4@TiO2/Cu2O composite: a simple, effective and reusable heterogeneous catalyst for ligand-free N-arylation of amines and nitrogen heterocycles
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Abstract: A practical and mild synthetic strategy has been investigated for the arylation of aromatic amines and nitrogen heterocycles using nano-magnetic-Fe3O4@TiO2/Cu2O composite and KOH as the base. The protocol does not require the use of expensive ligands. Notably, the catalyst is easily recoverable and reused by magnetic separation up to five runs without appreciable loss of catalytic activity. Graphical Abstract: [Figure not available: see fulltext.]
- Nemati, Firouzeh,Elhampour, Ali
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p. 7611 - 7624
(2016/09/20)
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- Methylene bridging 1,8-naphthyridine ligand and copper (I) complex, preparing method and application
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The invention discloses a methylene bridging 1,8-naphthyridine ligand and copper (I) complex, a preparing method and an application. The molecular formula of the methylene bridging 1,8-naphthyridine ligand and copper (I) complex is shown in the specificat
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Paragraph 0062; 0063; 0064; 0065; 0066; 0067; 0068; 0069
(2017/04/26)
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- Palladium(II) 9,10-phenanthrenequinone N-substituted thiosemicarbazone/semicarbazone complexes as efficient catalysts for N-arylation of imidazole
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A series of palladium complexes, [PdCl(L1-4)] (1-4) (L1 = 9,10-phenanthrenequinone thiosemicarbazone, L2 = 9,10-phenanthrenequinone methylthiosemicarbazone, L3 = 9,10-phenanthrenequinone phenylthiosemicarbazone, and L4 = 9,10-phenanthrenequinone semicarbazone), have been synthesized and characterized by elemental analyses, UV-vis, FT-IR, 1H and 13C NMR, and ESI-Mass spectroscopic methods. The catalytic efficiency of the synthesized complexes was examined against N-arylation of imidazole. The system works well with the electron-rich, -neutral, and -deficient aryl halides to afford the products in good to excellent yields. Sterically congested aryl halides and heteroaryl halides have also been used as substrates to provide N-arylated heterocycles. In addition, this methodology can be applicable to other substrates with N-containing heterocycles.
- Anitha, Panneerselvam,Manikandan, Rajendran,Viswanathamurthi, Periasamy
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p. 3537 - 3550
(2015/09/28)
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- Cu(0)@Al2O3/SiO2 NPs: An efficient reusable catalyst for the cross coupling reactions of aryl chlorides with amines and anilines
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The C-N cross coupling reaction of aryl chlorides with various alkyl/aryl amines catalyzed by copper nanoparticles impregnated on alumina/silica support (Cu(0)@Al2O3/SiO2) was investigated. The prepared catalyst was characterized for its intrinsic physico-chemical and textural properties using XRD, XPS, HR-TEM, BET surface area, SEM-EDAX, H2-TPR and ICP-AES techniques. The catalyst exhibits excellent reactivity and efficacy in the cross-coupling of a wide range of alkyl/aryl amines including challenging anilines with aryl chlorides. The catalyst offers significant advantages such as brevity, milder reaction conditions, excellent yields and high functional group tolerance for C-N cross coupling when compared with the other reported methods. Moreover, this atom-economical methodology does not require an additional ligand or co-catalyst/activator. The Cu(0)@Al2O3/SiO2 catalyst was efficiently applied to a gram scale synthesis of 7-chloro-4-(4-(2-nitrophenyl)piperazin-1-yl)quinolone (2k). The robustness of the catalyst was examined by reusing it for five consecutive runs.
- Reddy, P. Linga,Arundhathi,Rawat, Diwan S.
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p. 92121 - 92127
(2015/11/17)
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- Efficient copper-catalyzed ullmann reaction of aryl bromides with imidazoles in water promoted by a pH-Responsive ligand
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A series of 1,10-phenanthroline derivatives were used as supporting ligands for copper-catalyzed Ullmann reaction in neat water. The catalytic system based on 4,7-dihydroxy-1,10-phenanthroline has demonstrated the promising catalytic performances for aryl
- Lv, Rui,Wang, Yangxin,Zhou, Chunshan,Li, Liuyi,Wang, Ruihu
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p. 2978 - 2982
(2013/10/21)
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- 8-Hydroxyquinoline functionalized peg-1000 bridged Dicationic ionic liquid as a novel Ligand for copper-catalyzed n-Arylation of Imidazoles
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A novel 8-hydroxyquinoline functionalized PEG-1000 bridged dicationic ionic liquid ([HQ-PEG1000- DIL][BF4]) was synthesized and characterized. It was applied as an efficiently recyclable ligand for copper- catalyzed N-arylation of nitrogen-containing heterocycles with aryl halides. The catalytic system could be easily recovered and reused for at least five runs without obvious loss of catalytic activity.
- Wang, Ying-Lei,Luo, Jun,Liu, Zu-Liang
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p. 1007 - 1013
(2013/10/22)
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- An in situ generated CuI/metformin complex as a novel and efficient catalyst for C-N and C-O cross-coupling reactions
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An in situ generated complex of copper(I) and a biguanide, namely metformin, was found to be a highly efficient homogeneous catalyst in N/O-arylation reactions. The O-arylation of substituted phenols with various aryl iodides and bromides was also achieved using this copper catalyst to afford diaryl ethers in good to excellent yields in DMF. This heterogeneous copper catalyst also promotes the N-arylation of imidazole with a variety of aryl halides (Cl, Br, I) in acetonitrile.
- Ghorbani-Vaghei, Ramin,Hemmati, Saba,Veisi, Hojat
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p. 7095 - 7099
(2013/12/04)
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- A simple and efficient copper(II) complex as a catalyst for N-arylation of imidazoles
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Four inexpensive and air-/moisture-stable pyrrolecarbaldiminato-Cu complexes 1-4 were synthesized and evaluated to be a novel class of catalysts for the N-arylation of imidazoles with aryl halides. A variety of aryl iodides, bromides and activated aryl chlorides underwent the coupling with imidazoles, promoted by the catalyst 4, in moderate to good yields without the protection by an inert gas. Copyright
- Jiao, Yanli,Yan, Nannan,Xie, Jianwei,Ma, Xiaowei,Liu, Ping,Dai, Bin
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p. 267 - 270
(2013/08/24)
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- Efficient and reusable catalytic system of Cul-PEG for n-arylation of imidazoles
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A simple, efficient, and recyclable catalytic system of CuI-poly(ethylene glycol) (PEG) was developed for the N-arylation of imidazoles with aryl halides to afford corresponding N-arylimidazoles in good to excellent yields under mild conditions and free of any additional ligands and solvents. The isolation of the products was readily performed by simple extraction with ether, and the catalytic system could be reused without remarkable loss of activity even after six runs.
- Zhang, Qiang,Luo, Jun,Wei, Yunyang
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experimental part
p. 114 - 121
(2011/11/01)
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- A highly efficient Cu-catalyst system for N-arylation of azoles in water
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6,7-Dihydroquinolin-8(5H)-one oxime (L3) was found to serve as a superior ligand for the CuI-catalyzed N-arylation of imidazoles with aryl iodides, bromides, and electron-deficient chlorides in water. Moreover, the CuI/L3 catalyst system enabled the coupling reactions to take place smoothly with high yields under a low catalyst loading (0.1-1 mol% CuI and 0.2-2 mol% L3).
- Wang, Deping,Zhang, Fuxing,Kuang, Daizhi,Yu, Jiangxi,Li, Junhua
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supporting information; experimental part
p. 1268 - 1271
(2012/06/04)
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- Cheap Cu(I)/hexamethylenetetramine (HMTA) catalytic system for C-N coupling reactions
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An efficient C-N coupling reaction of aryl chlorides or bromides with imidazole was successfully performed with cheap and commercially available catalytic system Cu(I)/HMTA. Both aryl bromides and aryl chlorides have been effectively catalyzed by Cu/HMTA, giving products in moderate to good yields. Moreover, aryl halides bearing either electron-withdrawing groups or electron-donating groups could be used in the reaction. Taylor & Francis Group, LLC.
- Cao, Changsheng,Lu, Zhongbo,Cai, Zhengyuan,Pang, Guangsheng,Shi, Yanhui
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experimental part
p. 279 - 284
(2011/10/31)
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- Effect of central linkages on mesophase behavior of imidazolium-based rod-like ionic liquid crystals
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Two series of phenylbenzylether and benzanilide based rod-like imidazolium bromides and their nonionic precursors, the 1-phenyl-1H-imidazoles have been synthesized and the influence of the number and length of the alkyl chain(s) and the structure of the linking group in the aromatic core (-CH2O-, -COO-, -CONH-) on their mesophase self-assembly in ionic liquid crystalline phases were studied by POM, DSC and XRD. Upon decreasing the length of the N-terminal chain or by enlarging the number and length of the C-terminal chains, the sequence smectic (SmA)-hexagonal columnar (Colhex)-micellar cubic (CubI/Pm3n) was found for the ether based imidazolium salts; while only SmA and Colhex phases were observed for the related amides. The influence of the polarity of the central linkages, namely -CH 2O- and -CONH-, on the mesophase structure and stability is discussed and compared with related -COO- connected ILC.
- Cheng, Xiaohong,Su, Fawu,Huang, Rong,Gao, Hongfei,Prehm, Marko,Tschierske, Carsten
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scheme or table
p. 2274 - 2285
(2012/06/30)
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- Salts Comprising Aryl-Alkyl-Substituted Imidazolium and Triazolium Cations and the Use Thereof
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The present invention relates to salts comprising novel aryl-alkyl-substituted imidazolium and triazolium cations and arbitrary anions. The invention further relates to methods for the chemical conversion and separation of substances, comprising the salts
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Page/Page column 8-9; 11
(2011/05/08)
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- Self-assembly of imidazolium-based rodlike ionic liquid crystals: transition from lamellar to micellar organization
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By using aryl-amination chemistry, a series of rodlike 1-phenyl1H- imidazole-based liquid crystals (LCs) and related imidazolium-based ionic liquid crystals (ILCs) has been prepared. The number and length of the C-terminal chains (at the noncharged end of the rodlike core) and the length of the N-terminal chain (on the imidazolium unit in the ILCs) were modified and the influence of these structural parameters on the mode of self-assembly in LC phases was investigated by polarizing microscopy, differential scanning calorimetry, and X-ray diffraction. For the single-chain imidazole derivatives nematic phases (N) and bilayer SmA2 phases were found, but upon increasing the number of alkyl chains the LC phases were lost. For the related imidazolium salts LC phases were preserved upon increasing the number and length of the C-terminal chains and in this series it leads to the phase sequence SmA-columnar (Col)-micellar cubic (Cuby1/Pm3n). Elongation of the N-terminal chain gives the reversed sequence. Short Nterminal chains prefer an end-to-end packing of the mesogens in which these chains are separated from the C-terminal chains. Elongation of the N-terminal chain leads to a mixing of N- and C-terminal chains, which is accompanied by complete intercalation of the aromatic cores. In the smectic phases this gives rise to a transition from bilayer (SmA2) to monolayer smectic (SmA) phases. For the columnar and cubic phases the segregated end-to-end packing leads to core-shell aggregates. In this case, elongation of the N-terminal chains distorts core-shell formation and removes Cub1 and Col phases in favor of single-layer SmA phases. Hence, by tailoring the length of the N-terminal chain, a crossover from taper-shaped to polycatenar LC tectons was achieved, which provides a powerful tool for control of self-assembly in ILCs.
- Cheng, Xiaohong,Bai, Xueqing,Jing, Shan,Ebert, Helgard,Prehm, Marko,Tschierske, Carsten
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supporting information; experimental part
p. 4588 - 4601
(2010/08/19)
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- Mild conditions for copper-catalyzed N-arylation of imidazoles
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An efficient copper(I) bromide catalyzed N-arylation of azoles with a variety of aromatic bromides and iodides under mild conditions is reported. This reaction displayed great functional group compatibility and excellent reactive selectivity. Georg Thieme Verlag Stuttgart.
- Chen, Huaming,Wang, Deping,Wang, Xianyang,Huang, Wenlong,Cai, Qian,Ding, Ke
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experimental part
p. 1505 - 1511
(2010/09/14)
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- Simple synthesized Mannich bases as ligands in Cu-catalyzed N-arylation of imidazoles in water
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1,4-Bis(2-hydroxy-5-methoxybenzyl)piperazine and its analogues were used as efficient ligands for CuI-catalyzed N-arylation of imidazoles with aryl halides in water under mild conditions (120 °C for 12 h) with 10 mol% of CuI, 20 mol% of the Mannich base, and two equivalents of KOH or K2CO 3 in the presence of 10 mol% phase transfer catalyst (n-Bu) 4NBr. A variety of products were synthesized in moderate to excellent yields using this inexpensive catalytic system. Springer-Verlag 2010.
- Zhu, Yefeng,Shi, Yixing,Wei, Yunyang
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experimental part
p. 1009 - 1013
(2011/10/02)
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- A simple and efficient catalytic system for N-arylation of imidazoles in water
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A study was conducted to develop a simple and efficient catalytic system for N-arylation of immidazoles in water. Demonstrations revealed that the catalytic system contained a number of significant advantages. Some of these advantages included the use of water as a green solvent in place of volatile organic solvents and the catalysis was performed without an inert gas atmosphere and with low catalyst loading. Investigations revealed that the presence of catalyst and PTC were essential for the catalysis reaction. The scope of aryl halide substrates was investigated by using the catalytic system under the optimized reaction conditions. It was also demonstrated that the catalytic system tolerated a variety of functionalized aryl halides in the reaction, including nitrile, nitro, acetyl, and ether groups. The new catalytic system was applied to a variety of imidazole derivatives to expand the scope of the methodology.
- Wang, Yi,Wu, Zhiqing,Wang, Lixia,Li, Zhengkai,Zhou, Xiangge
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supporting information; experimental part
p. 8971 - 8974
(2010/04/05)
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- Pyridine N-oxides as ligands in Cu-catalyzed Af-arylation of imidazoles in water
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N-Arylation of imidazoles with aryl halides catalyzed by a combination of copper(II) sulfate and 1,2-bis(2-pyridyl)-ethane-N,N′-dioxide in water afforded up to 95% yield.
- Liang, Lei,Li, Zhengkai,Zhou, Xiangge
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supporting information; experimental part
p. 3294 - 3297
(2009/11/30)
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- Highly functional group tolerance in copper-catalyzed N-arylation of nitrogen-containing heterocycles under mild conditions
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A copper-catalyzed process has been developed for the N-arylation reaction under very mild conditions in the absence of additional ligand. This protocol could not only tolerate an array of thermally sensitive functional groups, but also achieve high chemoselectivity.
- Zhu, Liangbo,Li, Gaocan,Luo, Liang,Guo, Peng,Lan, Jingbo,You, Jingsong
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supporting information; experimental part
p. 2200 - 2202
(2009/07/01)
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- β-Ketoimine as an efficient ligand for copper-catalyzed N-arylation of nitrogen-containing heterocycles with aryl halides
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An efficient copper catalyst system, Cu2O/β-ketoimine L1, for the N-arylation of nitrogen-containing heterocycles with aryl iodides and bromides has been developed. The system works well with the electron-rich, -neutral, and -deficient aryl bromides to afford the products in good to excellent yields.
- Xue, Fei,Cai, Chengyi,Sun, Hongmei,Shen, Qi,Rui, Jiao
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p. 4386 - 4389
(2008/12/21)
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- Novel low-melting salts with donor-acceptor substituents as targets for second-order nonlinear optical applications
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We synthesized several novel low-melting ionic salts with donor-acceptor substituents and investigated their possible applications as second-order nonlinear optical materials. The Royal Society of Chemistry.
- Zhu, Zhi-Qiang,Xiang, Shaoji,Chen, Qing-Yun,Chen, Chaosen,Zeng, Zhuo,Cui, Yi-Ping,Xiao, Ji-Chang
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scheme or table
p. 5016 - 5018
(2009/06/06)
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- Synthesis and mesomorphic properties of rigid-core ionic liquid crystals
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Ionic liquid crystals combine the unique solvent properties of ionic liquids with self-organization found for liquid crystals. We report a detailed analysis of the structure-property relationship of a series of new imidazolium-based liquid crystals with an extended aromatic core. Investigated parameters include length and nature of the tails, the length of the rigid core, the lateral substitution pattern, and the nature of the counterion. Depending on the molecular structure, two mesophases were observed: a bilayered SmA 2 phase and the more common monolayered SmA phase, both strongly interdigitated. Most materials show mesophases stable to high temperatures. For some cases, crystallization could be suppressed, and room-temperature liquid crystalline phases were obtained. The mesomorphic properties of several mixtures of ionic liquid crystals were investigated. Many mixtures showed full miscibility and ideal mixing behavior; however, in some instances we observed, surprisingly, complete demixing of the component SmA phases. The ionic liquid crystals and mixtures presented have potential applications, due to their low melting temperatures, wide temperature ranges, and stability with extra ion-doping.
- Kouwer, Paul H. J.,Swager, Timothy M.
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p. 14042 - 14052
(2008/09/17)
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- A concept of supported amino acid ionic liquids and their application in metal scavenging and heterogeneous catalysis
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Novel supported task-specific ionic liquids have been developed for the first time via the ionic-pair coupling of imidazolium cation of the modified polystyrene support with L-proline. The materials have shown an efficient metal scavenging ability (e.g., Cul, Pd(OAc)2, Pd0, and IrCl3) without the aid of a nonimmobilized ionic liquid, which relies on the highly synergistic effect of the coordination with the nitrogen atom and the COO- group of the L-proline moiety, electrostatic forces, and steric protection. The resulting metal-soaked supported ionic liquids can be used as efficient heterogeneous catalysts. These materials have been investigated in the Cul-catalyzed N-arylation of nitrogen-containing heterocycles and exhibit much higher catalytic activity and a more extensive structural range of aryl and heteroaryl halides than those exhibited by free L-proline in combination with Cul both in the ionic liquid ([BMIM][BF 4]) and in the corresponding homogeneous reaction conditions. The Cul-soaked catalyst 4a-2 can be recycled for nine runs at least without any considerable loss of activity. To the best of our knowledge, our catalytic process is among the most efficient approaches to the N-arylation of imidazoles with aryl halides so far reported. Furthermore, the Pd-soaked material 4a-2 also shows higher catalytic activity in the solvent-free hydrogenation of styrene to ethylbenzene. This new concept is generally applicable and may easily be extended to other supported task-specific ionic liquids.
- Chen, Wen,Zhang, Yuanyuan,Zhu, Liangbo,Lan, Jingbo,Xie, Rugang,You, Jingsong
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p. 13879 - 13886
(2008/09/16)
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- Copper-catalyzed N-arylation of imidazoles and benzimidazoles
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(Chemical Equation Presented) 4,7-Dimethoxy-1,10-phenanthroline (L1c) was found to be an efficient ligand for the copper-catalyzed N-arylation of imidazoles and benzimidazoles with both aryl iodides and bromides under mild conditions. Further optimization of the system has revealed that the addition of poly(ethylene glycol) accelerates this reaction. A variety of hindered and functionalized imidazoles, benzimidazoles, and aryl halides were transformed in good to excellent yields. Heteroaryl halides were also coupled in moderate to good yields. We also present the results obtained from a series of coupling reactions, which directly compare the use of L1c with other recently reported ligands.
- Altman, Ryan A.,Koval, Erica D.,Buchwald, Stephen L.
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p. 6190 - 6199
(2008/02/10)
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- Simple copper salt-catalyzed N-arylation of nitrogen-containing heterocycles with aryl and heteroaryl halides
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(Chemical Equation Presented) Relatively mild and highly efficient CuI-catalyzed N-arylation procedures for nitrogen-containing heterocycles (e.g., imidazoles, benzimidazoles, pyrroles, pyrazoles, indoles, triazoles, etc.) with aryl and heteroaryl halides have been developed. The protocols can be performed easily and tolerate a number of functional groups, such as ester, nitrile, nitro, ketone, free hydroxyl, and free primary amine on the aryl halide.
- Zhu, Liangbo,Guo, Peng,Li, Gaocan,Lan, Jingbo,Xie, Rugang,You, Jingsong
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p. 8535 - 8538
(2008/03/11)
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- Highly efficient copper-catalyzed N-arylation of nitrogen-containing heterocycles with aryl and heteroaryl halides
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(Chemical Equation Presented) New (S)-pyrrolidinylmethylimidazole ligands (4a-c) have been readily synthesized in a straightforward fashion from least expensive starting materials in short steps in high yields. Relatively mild and highly efficient Cul-catalyzed N-arylation procedures for imidazoles with aryl and heteroaryl bromides or chlorides have been developed in the presence of 4a and Cs2CO3. It is important to note that the protocol could tolerate functional groups such as ester, nitrile, nitro, ketone, free hydroxyl, and free primary amine on the aryl halide. The protocol could also be applicable to other π-electron-rich nitrogen heterocycles (pyrrole, pyrazole, indole, benzimidazole, and triazole), affording the N-arylazoles in good to excellent yields.
- Zhu, Liangbo,Cheng, Liang,Zhang, Yuxi,Xie, Rugang,You, Jingsong
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p. 2737 - 2743
(2008/02/05)
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- 4,7-Dimethoxy-1,10-phenanthroline: An excellent ligand for the Cu-catalyzed N-arylation of imidazoles
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4,7-Dimethoxy-1,10-phenanthroline (L) was found to be an efficient ligand for the copper-catalyzed N-arylation of imidazole with aryl iodides and bromides under mild conditions. A variety of hindered and functionalized imidazoles and aryl halides were transformed in good to excellent yields.
- Altman, Ryan A.,Buchwald, Stephen L.
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p. 2779 - 2782
(2007/10/03)
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- Model studies of the histidine-tyrosine cross-link in cytochrome c oxidase reveal the flexible substituent effect of the imidazole moiety
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(Chemical Equation Presented) Experimental and theoretical studies were carried out to interrogate the effect of an imidazole substituent in each of the ortho, meta, and para positions on the pKa, E°, and O-H BDE of phenol. The results reveal t
- Pratt, Derek A.,Pesavento, Russell P.,Van Der Donk, Wilfred A.
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p. 2735 - 2738
(2007/10/03)
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- 3-Imidazolium cephalosporin derivatives
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A cephalosporin compound substituted by imidazolium ring in 3-position of cephem having the following formula (I), and pharmaceutically acceptable salt thereof, STR1 wherein R1 is an organic residue known in β-lactam antibiotics, R2 is hydrogen atom or methoxy, n is 0 or 1, A is a nitrogen-containing group constituting imidazolium ring, is useful as an agent for preventing and treating bacterial infections.
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