3718-03-4Relevant academic research and scientific papers
Microwave assisted synthesis and potent antimicrobial activity of some novel 1,3-dialkyl-2-arylbenzimidazolium salts
Eren, Bilge,Yilmaz, ?zge,?etin, Gül?in,Darcan, Cihan
, p. 621 - 633 (2018/06/06)
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.
A mild and expedient one-pot synthesis of substituted benzimidazoles in water using a phase-transfer catalyst
Chakrabarty, Manas,Karmakar, Sulakshana,Mukherjee, Ratna,Arima, Shiho,Harigaya, Yoshihiro
experimental part, p. 375 - 380 (2010/05/01)
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.
A Keggin heteropoly acid as an efficient catalyst for an expeditious, one-pot synthesis of 1-methyl-2-(hetero)arylbenzimidazoles
Chakrabarty, Manas,Mukherji, Ajanta,Mukherjee, Ratna,Arima, Shiho,Harigaya, Yoshihiro
, p. 5239 - 5242 (2008/02/08)
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.
Tosic acid-on-silica gel: A cheap and eco-friendly catalyst for a convenient one-pot synthesis of substituted benzimidazoles
Chakrabarty, Manas,Mukherjee, Ratna,Karmakar, Sulakshana,Harigaya, Yoshihiro
, p. 1279 - 1282 (2008/03/28)
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.
Intermolecular SNAr of the heterocycle-activated nitro and fluoro groups-application in the synthesis of polyazamacrocyclic ligands
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Page/Page column 30, (2010/02/14)
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
Preparation of 2-substituted benzimidazoles and related heterocycles directly from activated alcohols using TOP methodology
Wilfred, Cecilia D.,Taylor, Richard J. K.
, p. 1628 - 1630 (2007/10/03)
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.
Intramolecular Aromatic Nucleophilic Substitution of the Benzimidazole-Activated Nitro Group
Fekner, Tomasz,Gallucci, Judith,Chan, Michael K.
, p. 4795 - 4798 (2007/10/03)
(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
The reaction of benzimidazolium derivatives with superoxide
Nagata, Kazuhiro,Itoh, Takashi,Okada, Mamiko,Ohsawa, Akio
, p. 6569 - 6580 (2007/10/03)
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.
SYNTHESIS OF 2-ARYL-BENZIMIDAZOLES VIA CYCLIC N-DIAZONIUM IONS
Kreher, Richard,Bergmann, Udo
, p. 1725 - 1728 (2007/10/02)
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
