- Preparation of 2-substituted benzimidazoles and related heterocycles directly from activated alcohols using TOP methodology
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A one-pot procedure for preparing 2-substituted benzimidazoles directly from activated alcohols in good to excellent yields using a new Tandem Oxidation Process (TOP) is reported. The use of this methodology to prepare 2-substituted benzoxazoles and 2-substituted benzothiazoles is also described.
- Wilfred, Cecilia D.,Taylor, Richard J. K.
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- Bimetallic Cooperative Catalysis for Decarbonylative Heteroarylation of Carboxylic Acids via C-O/C-H Coupling
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Cooperative bimetallic catalysis is a fundamental approach in modern synthetic chemistry. We report bimetallic cooperative catalysis for the direct decarbonylative heteroarylation of ubiquitous carboxylic acids via acyl C-O/C-H coupling. This novel catalytic system exploits the cooperative action of a copper catalyst and a palladium catalyst in decarbonylation, which enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of carboxylic acids with heteroarenes in the absence of prefunctionalization or directing groups. This cooperative decarbonylative method uses common carboxylic acids and shows a remarkably broad substrate scope (>70 examples), including late-stage modification of pharmaceuticals and streamlined synthesis of bioactive agents. Extensive mechanistic and computational studies were conducted to gain insight into the mechanism of the reaction. The key step involves intersection of the two catalytic cycles via transmetallation of the copper–aryl species with the palladium(II) intermediate generated by oxidative addition/decarbonylation.
- Liu, Chengwei,Ji, Chong-Lei,Zhou, Tongliang,Hong, Xin,Szostak, Michal
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supporting information
p. 10690 - 10699
(2021/04/09)
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- Ruthenium-Catalyzed ortho- And meta-H/D Exchange of Arenes
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Ruthenium-catalyzed aromatic H/D exchange in [D4]acetic acid has been developed. By using N-heteroarenes as directing groups, both ortho and meta positions are selectively deuterated with high levels of D incorporation. Moreover, this strategy provides an alternative way to achieve meta-C-H activation.
- Zhao, Liang-Liang,Liu, Wei,Zhang, Zengyu,Zhao, Hongyan,Wang, Qi,Yan, Xiaoyu
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p. 10023 - 10027
(2019/12/24)
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- An intramolecular C(sp3)-H imination using PhI-m CPBA
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Herein, a highly exothermic primary amine-polyvalent iodine reaction has been used successfully for selective functionalization of acidic C(sp3)-H groups for a dehydrogenative C-H imination reaction by 4H elimination. Overall, C(sp3)-H imination at 1,5 distances was readily done via organocatalysis using PhI (10 mol%)-mCPBA under ambient conditions.
- Bose, Anima,Maiti, Saikat,Sau, Sudip,Mal, Prasenjit
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p. 2066 - 2069
(2019/02/19)
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- Intramolecular C(sp3)–H Imination towards Benzimidazoles Using Tetrabutylammonium Iodide and tBuOOH
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Development of sustainable and economically viable methods is challenging but desired in organic synthesis. Herein, intramolecular C(sp3)–H imination between a free amine group and N-methylene group is established using TBAI (20 mol %)-TBHP (3.0 equiv.) in DMSO which is found to be an inexpensive replacement of PhI-mCPBA in HFIP.
- Bose, Anima,Sau, Sudip,Mal, Prasenjit
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p. 4105 - 4109
(2019/06/24)
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- Microwave assisted synthesis and potent antimicrobial activity of some novel 1,3-dialkyl-2-arylbenzimidazolium salts
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Background: Benzimidazolium salts include biologically active benzimidazole ring. Some benzimidazolium salts and their metal complexes, containing different groups, showed remarkable antibacterial, antifungal and antitumor effects. Most of these studies are generally related with the 2-unsubstituted derivatives of benzimidazolium salts which named as N-heterocyclic carbenes (NHCs). To enhance the efficacy of the benzimidazoles in the biological systems, it is very important to overcome the insolubility problem. For this reason and previously indicated structural importance of the benzimidazolium salts, 1,3-dialkyl halide salts of the 2-arylbenzimidazoles, are of focus in this work. To the best of our knowledge, this is the first report that describes the microwave assisted synthesis and antimicrobial activity of 2-arylsubstituted benzimidazolium salts. Methods: A series of novel 1,3-dialkyl-2-arylbenzimidazolium salts (8-28) were synthesized via the N-alkylation of 1-methyl-2-arylbenzimidazole derivatives (1-7) with alkyl halides under microwave conditions by using small amount of DMF. The results were also compared with conventional heating under reflux. Structures of the products were confirmed by using 1H-NMR, 13C-NMR, FTIR spectroscopic techniques. All of the synthesized compounds were screened for their in vitro antimicrobial activities using microbroth tube dilution and disc diffusion methods. Results: Considering the reactions repeated by classical heating, it was determined that the reaction times were decreased from 3-6 hours to 5-35 minutes under microwave. Additionally, yields have increased from 4-71 % to 64-96 % ranges. Considering the whole antimicrobial activity studies, MIC values of newly synthesized benzimidazolium salts 8-28 (1.95->1500 μg/ml) are remarkably smaller than parent benzimidazoles 1-7 (62.5->1500 μg/ml) on the studied microorganisms. Conclusion: The microwave method is advantageous regarding the usage of mild conditions and small amounts of solvent, easy purification and achieving high yields in short times. The antimicrobial activity studies demonstrate that newly synthesized salts (8-28) are effective mostly on grampositives and eukaryotic microorganisms. Compounds 16, 18, 19, 24, 25 and 27 were found to be the most effective inhibitors of growth in both gram-positive bacteria and eukaryotes. Thus, the synthesized compounds in this study may aid the treatment of fungal and bacterial diseases. The results of this study are of great significance in the areas of synthetic organic chemistry, microbiology, pharmaceutical chemistry and chemical catalysis.
- Eren, Bilge,Yilmaz, ?zge,?etin, Gül?in,Darcan, Cihan
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p. 621 - 633
(2018/06/06)
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- Synthesis of 1,2-disubstituted benzimidazoles using an aza-Wittig-equivalent process
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A synthetic approach for 1,2-disubstituted benzimidazoles has been successfully designed based on effective C-N bond construction, which demonstrated mild reaction conditions and excellent yields. The method involves treating derivatives of o-phenylenediamine with tert-butanesulfoxide and NBS under acidic conditions, which undergoes an aza-Wittig-equivalent process to afford the desired products. Using this method, a series of benzimidazoles containing multiple functional groups with varying electronic effects have been successfully constructed.
- Chen, Yuan,Xu, Fanghui,Sun, Zhihua
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p. 44421 - 44425
(2017/09/26)
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- Catalytic Oxidative Coupling of Primary Amines under Air: A Flexible Route to Benzimidazole Derivatives
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Benzimidazoles are of fundamental importance in chemistry and biology, and the development of efficient, environmentally benign methods for their preparation remains a key challenge for organic chemists. In a biomimetic approach inspired by copper amine oxidases, we disclose herein the scope and factors influencing the success of the cooperative action of CuBr2 as electron-transfer mediator and a topaquinone-like substrate-selective catalyst in the oxidative cyclocondensation of primary amines with o-aminoanilines. This one-pot atom-economic multistep process, which works under green conditions with ambient air as the terminal oxidant, low loadings of catalyst, and equimolar amounts of commercially available amine substrates, is particularly suitable for the preparation of 1,2-disubstituted benzimidazoles. Furthermore, it allows the functionalization of nonactivated primary aliphatic amines, which are known to be challenging substrates for non-enzymatic catalytic aerobic systems.
- Nguyen, Khac Minh Huy,Largeron, Martine
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supporting information
p. 1025 - 1032
(2016/03/01)
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- C-H arylation and alkenylation of imidazoles by nickel catalysis: Solvent-accelerated imidazole C-H activation
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The first nickel-catalyzed C-H arylations and alkenylations of imidazoles with phenol and enol derivatives are described. Under the influence of Ni(OTf)2/dcype/K3PO4 (dcype: 1,2-bis(dicyclohexylphosphino)ethane) in t-amyl alcohol, imidazoles can undergo C-H arylation with phenol derivatives. The C-H arylation of imidazoles with chloroarenes as well as that of thiazoles and oxazoles with phenol derivatives can also be achieved with this catalytic system. By changing the ligand to dcypt (3,4-bis(dicyclohexylphosphino)thiophene), enol derivatives could also be employed as coupling partners achieving the C-H alkenylation of imidazoles as well as thiazoles and oxazoles. Thus, a range of C2-arylated and alkenylated azoles can be synthesized using this newly developed nickel-based catalytic system. The key to the success of the C-H coupling of imidazoles is the use of a tertiary alcohol as solvent. This also allows the use of an air-stable nickel(ii) salt as the catalyst precursor.
- Muto, Kei,Hatakeyama, Taito,Yamaguchi, Junichiro,Itami, Kenichiro
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p. 6792 - 6798
(2015/11/24)
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- Solid-phase synthesis of benzazoles, quinazolines, and quinazolinones using an alkoxyamine linker
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An alkoxyamine linker was applied for the solid-phase synthesis of benzazoles, quinazolines, and quinazolinones. Aromatic aldehydes were anchored by aldoxime linkage. After some reactions on a solid support, the products were cleaved with paraformaldehyde under the acidic conditions to afford the corresponding aldehydes, which were subsequently subjected to oxidative coupling with 2-substituted anilines under air atmosphere to give the desired compounds.
- Yamaguchi, Kota,Noda, Takeshi,Higuchi, Yusuke,Aoki, Naoyuki,Yamaguchi, Rika,Kubo, Miwa,Harada, Kenichi,Fukuyama, Yoshiyasu,Hioki, Hideaki
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p. 5793 - 5797
(2015/02/18)
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- Nanoparticle mediated organic synthesis (NAMO-synthesis): CuI-NP catalyzed ligand free amidation of aryl halides
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The first CuI-nanoparticle catalyzed ligand free synthesis of N-aryl amides from aryl halides and arylamides/cyclic amides has been developed. This methodology is further extended for the synthesis of nitrogen heterocycles such as benzimidazole, and quinazolinone via intermolecular amidation reaction followed by cyclization. TEM images of the CuI-NP catalyst showed spherical, well-dispersed particles which provide large surface area for reactivity and have good recyclability. This journal is
- Kumar, Atul,Bishnoi, Ajay Kumar
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p. 41631 - 41635
(2015/05/20)
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- Nanoparticle mediated organic synthesis (NAMO-synthesis): CuI-NP catalyzed ligand free amidation of aryl halides
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The first CuI-nanoparticle catalyzed ligand free synthesis of N-aryl amides from aryl halides and arylamides/cyclic amides has been developed. This methodology is further extended for the synthesis of nitrogen heterocycles such as benzimidazole, and quinazolinone via intermolecular amidation reaction followed by cyclization. TEM images of the CuI-NP catalyst showed spherical, well-dispersed particles which provide large surface area for reactivity and have good recyclability. This journal is
- Kumar, Atul,Bishnoi, Ajay Kumar
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p. 41631 - 41635
(2014/12/10)
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- N -heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed direct C-H bond arylation of (Benz)imidazoles with aryl chlorides
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(Benz)imidazoles can be efficiently functionalized by (hetero)aryl chlorides via direct C-H bond arylation in the presence of a well-defined NHC-Pd(II)-Im complex. Under the optimal conditions, various activated, unactivated, and deactivated (hetero)aryl chlorides were successfully applied as the arylating reagents to achieve the 2-(hetero)aryl (benz)imidazoles in acceptable to high yields, giving a facile and alternative methodology for the direct C-H bond arylation of (benz)imidazoles.
- Gu, Zheng-Song,Chen, Wen-Xin,Shao, Li-Xiong
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p. 5806 - 5811
(2014/07/08)
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- Gold nanoparticles supported on titanium dioxide: An efficient catalyst for highly selective synthesis of benzoxazoles and benzimidazoles
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A highly efficient and selective reaction for the synthesis of 2-substituted benzoxazoles and benzimidazoles catalyzed by Au/TiO2 has been developed via two hydrogen-transfer processes. This reaction has a good tolerance to air and water, a wide substrate scope, and represents a new avenue for practical C-N and C-O bond formation. More importantly, no additional additives, oxidants and reductants are required for the reaction and the catalyst can be recovered and reused readily. This journal is the Partner Organisations 2014.
- Tang, Lin,Guo, Xuefeng,Yang, Yu,Zha, Zhenggen,Wang, Zhiyong
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supporting information
p. 6145 - 6148
(2014/06/09)
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- Formation of C=N bonds by the release of H2: A new strategy for synthesis of imines and benzazoles
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A new strategy for synthesis of imines using the approach of release of H2 has been developed. This oxidant- and acceptor-free Pd/C catalysis protocol is further applied to synthesis of benzoxazoles, benzimidazoles, and benzothiazoles through a one-pot cascade reaction with notably high yields. The Royal Society of Chemistry 2013.
- Jin, Xukang,Liu, Yuxiao,Lu, Qiongqiong,Yang, Dejun,Sun, Jiangkai,Qin, Shuangshuang,Zhang, Jingwu,Shen, Jiaxuan,Chu, Changhu,Liu, Renhua
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supporting information
p. 3776 - 3780
(2014/03/21)
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- An efficient arylation of benzoazoles with aryl bromides by a practical palladium-copper cocatalytic system
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A practical, efficient Pd(OAc)2/Cu(II)/PPh3 cocatalytic system has been developed. With only 1 mol% Pd(OAc)2, 20 mol% copper(II) salt, and 0.5 equiv of inexpensive PPh3 as ligand, the direct arylation of benzoazoles with aryl bromides could be performed smoothly in mild condition, affording the desired arylated benzoazoles in good yields (75-93%).
- Yan, Xue-Ming,Mao, Xue-Rong,Huang, Zhi-Zhen
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experimental part
p. 1371 - 1376
(2011/06/27)
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- Palladium-catalyzed carbonylative C-H activation of heteroarenes
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Not only carbonylation: The first carbonylative cross-coupling reactions towards ketones using C-H activation have been developed. Various heteroarenes, such as oxazoles, thiazoles, and imidazoles were used as coupling partners in this methodology. DBU =
- Wu, Xiao-Feng,Anbarasan, Pazhamalai,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 7316 - 7319
(2010/11/05)
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- A mild and expedient one-pot synthesis of substituted benzimidazoles in water using a phase-transfer catalyst
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1-Alkyl/phenyl-2-arylbenzimidazoles have been synthesized in very good to excellent yields by a one-pot condensation of N-alkyl/phenyl-o-phenylenediamines with aryl aldehydes in water at room temperature using cetylpyridinium bromide as a cheap and eco-friendly catalyst.
- Chakrabarty, Manas,Karmakar, Sulakshana,Mukherjee, Ratna,Arima, Shiho,Harigaya, Yoshihiro
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experimental part
p. 375 - 380
(2010/05/01)
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- Composition For the Vapor Phase Dehydrohalogenation of 1,1,2-Trihaloethane To 1,1-Dihaloethylene and Methods For Preparing and Using Such Composition
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Described are compositions adapted to catalyze the vapor phase dehydrohalogenation of 1,1,2-trihaloethane to 1,1-dihaloethylene, e.g., 1,1,2-trichloroethane to vinylidene chloride. These materials include activated carbon and at least one benzimidazole-containing material defined herein as including benzimidazole, a derivative thereof, a salt thereof or mixtures thereof. Also described are methods for producing and using these catalytic compositions.
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Page/Page column 5-6
(2008/12/07)
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- Tosic acid-on-silica gel: A cheap and eco-friendly catalyst for a convenient one-pot synthesis of substituted benzimidazoles
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2-Substituted and 1,2-disubstited benzimidazoles were prepared efficiently from o-phenylenediamines and aryl aldehydes using p-toluenesulphonic acid (5∈mol%)-on-silica gel as a cheap and environmentally benign catalyst.
- Chakrabarty, Manas,Mukherjee, Ratna,Karmakar, Sulakshana,Harigaya, Yoshihiro
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p. 1279 - 1282
(2008/03/28)
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- A Keggin heteropoly acid as an efficient catalyst for an expeditious, one-pot synthesis of 1-methyl-2-(hetero)arylbenzimidazoles
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The Keggin heteropoly acid, silicotungstic acid, H4SiW12O40, has been demonstrated to be highly efficient for an expeditious, one-pot synthesis of 1-methyl-2-(hetero)arylbenzimidazoles from N-methyl-1,2-phenylenediamine and (hetero)aryl aldehydes in ethyl acetate at room temperature. The catalyst works equally well for N-phenyl-1,2-phenylenediamine.
- Chakrabarty, Manas,Mukherji, Ajanta,Mukherjee, Ratna,Arima, Shiho,Harigaya, Yoshihiro
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p. 5239 - 5242
(2008/02/08)
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- COMPOSITION FOR THE VAPOR PHASE DEHYDROHALOGENATION OF 1,1,2-TRIHALOETHANE TO 1,1-DIHALOETHYLENE AND METHODS FOR PREPARING AND USING SUCH COMPOSITIONS
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Described are compositions adapted to catalyze the vapor phase dehydrohalogenation of 1,1,2-trihaloethane to 1,1-dihaloethylene, e.g., 1,1,2-trichloroethane to vinylidene chloride. These materials include activated carbon and at least one benzimidazole-containing material defined herein as including benzimidazole, a derivative thereof, a salt thereof or mixtures thereof. Also described are methods for producing and using these catalytic compositions.
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Page/Page column 18
(2010/11/25)
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- Intermolecular SNAr of the heterocycle-activated nitro and fluoro groups-application in the synthesis of polyazamacrocyclic ligands
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A new class of tetracylic benzimidazole compounds and derivatives thereof. Additionally provided is a synthetic route for the generation of these and related compounds via Intramolecular Aromatic Nucleophilic Substitution (SNAr) of the Benzimid
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Page/Page column 30
(2010/02/14)
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- Smart cleavage reactions: The synthesis of benzimidazoles and benzothiazoles from polymer-bound esters
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The preparation of an array of benzimidazoles and benzothiazoles from polymer-bound esters is described. Polymer-bound esters were treated with 2-aminothiophenols or 1,2-phenylenediamines in the presence of a Lewis acid to afford the corresponding benzothiazole or benzimidazole cleavage products. The reaction of 2-aminophenols with the polymer-bound esters failed to give the desired benzoxazole products using this procedure.
- Matsushita, Hana,Lee, Sang-Hyeup,Joung, Meyoungju,Clapham, Bruce,Janda, Kim D.
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p. 313 - 316
(2007/10/03)
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- Intramolecular Aromatic Nucleophilic Substitution of the Benzimidazole-Activated Nitro Group
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(Equation Presented) A wide range of 2-(2-nitrophenyl)-1H-benzimidazoles undergo high-yielding intramolecular SNAr of nitrite with N-pendant alkoxides under mild conditions (DMF, rt). When this operationally simple process is carried out at ele
- Fekner, Tomasz,Gallucci, Judith,Chan, Michael K.
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p. 4795 - 4798
(2007/10/03)
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- The reaction of benzimidazolium derivatives with superoxide
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1-Ethoxycarbonyl-3-methylbenzimidazolium salts, which have an electron deficient imidazolium ring and a carbamate moiety, were allowed to react with superoxide to give ring-opened products and 1-methylbenzimidazoles. The products ratio varied on the change of the counter cation species of superoxide. When 1,1',3,3'-tetramethyl-2,2'-bibenzimidazolium salt reacted with KO2, chemiluminescence was observed which did not occur by the use of KOH or H2O2 as a reagent.
- Nagata, Kazuhiro,Itoh, Takashi,Okada, Mamiko,Ohsawa, Akio
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p. 6569 - 6580
(2007/10/03)
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- SYNTHESIS OF 2-ARYL-BENZIMIDAZOLES VIA CYCLIC N-DIAZONIUM IONS
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Condensation of 2-azido-aniline with aromatic aldehydes and protonation with tetrafluoroboric acid lead to phenylogous azidoiminium salts.Subsequent cyclisation to cyclic N-diazonium ions and N2-elimination give rise to the formation of 2-aryl-benzimidazo
- Kreher, Richard,Bergmann, Udo
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p. 1725 - 1728
(2007/10/02)
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