- Reusable nano-zirconia-catalyzed synthesis of benzimidazoles and their antibacterial and antifungal activities
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In this article, a zirconia-based nano-catalyst (Nano-ZrO2 ), with intermolecular C-N bond formation for the synthesis of various benzimidazole-fused heterocycles in a concise method is reported. The robustness of this reaction is demonstrated
- Ahmad, Naushad,Ahmed, Faheem,Albalawi, Fadwa,Alomar, Suliman Yousef,Basaveswara Rao, M. V.,Cheedarala, Ravi Kumar,Naidu, Tentu Manohra,Rao, Nalla Krishna,Rao, Tentu Nageswara,Reddy, G. Rajasekhar
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- Synthesis and fungicidal activity of novel 6H-benzimidazo[1,2-c][1,3]benzoxazin-6-ones
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[Figure not available: see fulltext.] A series of 6H-benzimidazo[1,2-c][1,3]benzoxazin-6-one derivatives were synthesized in moderate to good yield by reaction of 2-(1H-benzimidazol-2-yl)phenols with triphosgene, and the structures of the target compounds
- Jiao, Yinchun,Ma, Caixia,Tan, Yuhuan,Tang, Zilong
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p. 581 - 587
(2021/06/16)
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- The ninhydrin core as carbonyl source to access 2-(2′-hydroxyaryl)benzimidazoles exploiting the ortho selectivity of ninhydrin-phenol adducts
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Although ninhydrin is an essential analytical tool in biochemical and forensic sciences, for the past several years, it has been employed as efficient building block for diverse organic scaffolds. In the present work, the ortho selectivity of ninhydrin-phenol adducts has been exploited to obtain 2-(2′-hydroxyaryl)benzimidazoles which are well known excited state intramolecular proton transfer (ESIPT) fluorophores. Under acidic condition, 3-(2-hydroxyaroyl)isoindolin-1-one intermediate generated in situ from ninhydrin-phenol adducts was treated with o-phenylenediamine resulting benzimidazole scaffolds via a two-step one pot strategy.
- Das, Suven,Maity, Suvendu,Ghosh, Prasanta,Dutta, Arpita
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p. 2862 - 2872
(2021/08/13)
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- Synthesis of new TCH/Ni-based nanocomposite supported on SBA-15 and its catalytic application for preparation of benzimidazole and perimidine derivatives
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A stable nickel-decorated SBA-15 nanocomposite (Ni/TCH@SBA-15) was synthesized through surface modification of silica nanoparticles with 3-chloropropyltriethoxysilane (CPTES) and thiocarbohydrazide (TCH) followed by metal–ligand coordination with Ni (II). The structure of this organometallic nanocomposite was characterized by Fourier transform-infrared, field emission-scanning electron microscopy, EDAX, transmission electron microscopy, atomic absorption spectroscopy and N2 adsorption–desorption (Brunauer–Emmett–Teller) techniques. The catalytic performance of Ni/TCH@SBA-15 (NNTS-15) was determined for the synthesis of 2-aryl-substituted benzimidazoles and 2,3-dihydroperimidines. The excellent yields within shorter reaction times, simplicity of catalytic methods, non-toxicity and clean reactions, mild reaction conditions and easy work-up procedure are the important merits of these synthetic protocols. Moreover, the Ni (II) bonded to the SBA-15 surface was stable under the catalytic reaction conditions resulting in its efficient recycling and reuse.
- Kalhor, Mehdi,Rezaee-Baroonaghi, Fahimeh,Dadras, Akbar,Zarnegar, Zohre
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- Green synthesis of benzimidazole derivatives under ultrasound irradiation using Cu-Schiff base complexes embedded over MCM-41 as efficient and reusable catalysts
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We have synthesized two recoverable catalysts by covalently attaching complexes such as Cu-complex-phen and Cu-complex-bipy on MCM-41 through a greener synthetic route. FT-IR, EDX, SEM and TEM microscopy, XRD analysis, N2 adsorption and desorpt
- Bharathi, M.,Indira, S.,Induja, E.,Mahalakshmi, T.,Shamuga Bharathi, K.,Vinoth, G.
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- Br?nsted acidic reduced graphene oxide as a sustainable carbocatalyst: A selective method for the synthesis of C-2-substituted benzimidazole
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Br?nsted acidic reduced graphene acts as an efficient and sustainable carbocatalyst for the selective synthesis of C-2-substituted benzimidazoles under ambient conditions. A massive influx of sulphonic acid group on reduced graphene oxide surface gives graphene sulfonic acid (G-SO3H), which acts as a Br?nsted acidic catalyst for the synthesis of a series of benzimidazoles under mild conditions. The present methodology is a revamp of the benzimidazole synthesis with broad functional group tolerance in shorter time. G-SO3H provides an operationally simple, metal-free condition and is amenable to gram-scale production. Pyridine adsorption studies prove the catalytically responsible Br?nsted acidity of the catalyst. The catalyst is highly stable for several cycles without any loss of activity, which is evidenced by the FT-IR, PXRD and TEM characterization of the reused catalyst.
- Karthik, Murugan,Suresh, Palaniswamy
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p. 17931 - 17938
(2018/11/21)
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- Highly efficient AgNO3-catalyzed approach to 2-(benzo[d]azol-2-yl)phenols from salicylaldehydes with 2-aminothiophenol, 2-aminophenol and benzene-1,2-diamine
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A new, convenient and efficient AgNO3-catalyzed strategy for the preparation of 2-(benzo[d]azol-2-yl)phenol derivatives in good to excellent yields (63–98%) is described. The reaction proceeds via condensation/intramolecular nucleophilic addition/oxidation process between substituted salicylaldehydes and 2-aminothiophenol, 2-aminophenol or benzene-1,2-diamine under mild reaction conditions. Notably, this reaction utilizes cheap AgNO3 as a readily available and low-cost benign oxidant at low catalyst loadings with excellent functional group tolerance.
- He, Xinwei,Wu, Yuhao,Jin, Wenjing,Wang, Xiaoshun,Wu, Cong,Shang, Yongjia
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- Mesoporous silica supported ytterbium as catalyst for synthesis of 1,2-disubstituted benzimidazoles and 2-substituted benzimidazoles
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The benzimidazole ring is an important pharmacophore in contemporary drug discovery. Thus, effort to identifying new compounds containing benzimidazole scaffolds have gained much attention in recent years. In the present study, MCM-41 type mesoporous silica with large pore (l-MSN) supported ytterbium was successfully prepared by wet impregnation method. Among rare earth metal salts, ytterbium triflate has already been widely investigated as a catalyst in organic synthesis but less toxic ytterbium oxide has yet to be explored. Relatively high abundance and low cost of ytterbium with respect to many catalytically active metals (e.g. Pd, Au, Ru, Ir, Pt) offer an opportunity to develop sustainable catalysts for organic conversions. The catalyst has been characterized by various techniques including nitrogen adsorption, FT-IR, TEM, SEM, EDX technique and elemental mapping. The obtained materials exhibit high surface area and a narrow distribution of mesoporosity. The catalytic performance of the Yb@l–MSNs was tested by synthesis of 1,2-disubstituted benzimidazoles and 2-substituted benzimidazoles through the coupling of aldehydes with o-phenylenediamine. The catalyst resulted in excellent yields in short reaction times and the reaction showed tolerance toward both electron-donating and electron-withdrawing functional groups at room temperature. A particularly interesting finding was the solvent selectivity of this reaction; namely, 1,2-disubstituted benzimidazoles generated as major product in water-ethanol, while the 2-substituted benzimidazoles was generated exclusively in non-polar solvents like toluene.
- Samanta, Partha Kumar,Banerjee, Rumeli,Richards, Ryan M.,Biswas, Papu
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- A Magnetic Heterogeneous Biocatalyst Composed of Immobilized Laccase and 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) for Green One-Pot Cascade Synthesis of 2-Substituted Benzimidazole and Benzoxazole Derivatives under Mild Reaction Conditions
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The design of reusable high-performance heterogeneous catalysts via the immobilization of chemical and biochemical species on magnetic nanoparticles increases the efficiency of catalytic systems by facilitating easy, fast, and clean separation processes. Laccase and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl were separately immobilized on amine functionalized iron (II, III) oxide nanoparticles with covalent bonding using glutaraldehyde as a coupling reagent. The prepared catalyst was used to synthesize 12 benzoxazole and benzimidazole derivatives. The one-pot, two-step enzymatic aerobic oxidation reaction included the condensation of in situ-produced salicylaldehyde derivatives with aromatic amines, followed by an enzymatic dehydrogenation process. Optimal reaction conditions consisted of a citrate buffer (10 mM, pH 4.5) at 40 °C for an incubation time of 10 h and a heterogeneous catalyst containing immobilized laccase (80 mg, 100 U) and immobilized 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) (40 mg, 2 mol%). The catalyst retained more than 85% of its initial activity after 10 runs. In addition to the potential for reuse without significant losses in performance, eco-friendly attributes of this catalytic system include its high catalytic activity and the ease with which it can be recovered from the reaction mixture using an external magnet. (Figure presented.).
- Mogharabi-Manzari, Mehdi,Kiani, Mahshid,Aryanejad, Sima,Imanparast, Somaye,Amini, Mohsen,Faramarzi, Mohammad Ali
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p. 3563 - 3571
(2018/09/22)
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- Efficient preparation of acidic ionic liquid-functionalized reduced graphene oxide and its catalytic performance in synthesis of benzimidazole derivatives
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Abstract: This article reports an efficient method with a simple workup for the facile synthesis of benzimidazole derivatives using an acidic ionic liquid covalently supported on graphene sheets. The catalyst was efficiently synthesized and characterized
- Hanoon,Kowsari,Abdouss,Zandi,Ghasemi
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p. 1751 - 1766
(2017/02/15)
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- 6,7-Dihydrobenzo[f]benzo[4,5]imidazo[1,2-d][1,4]oxazepine derivatives as selective inhibitors of PI3Kα
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Twenty eight 6,7-dihydrobenzo[f]benzo[4,5]imidazo[1,2-d][1,4]oxazepine derivatives were synthesized and evaluated their biological activities as PI3K inhibitors. Biological evaluation against four human tumor cell lines revealed that most target compounds
- Yin, Yong,Zhang, Yan-Qing,Jin, Biao,Sha, Shao,Wu, Xun,Sangani, Chetan B.,Wang, She-Feng,Qiao, Fang,Lu, Ai-Min,Lv, Peng-Cheng,Zhu, Hai-Liang
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p. 1231 - 1240
(2015/03/04)
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- Photocatalysis by 3,6-disubstituted-s-tetrazine: Visible-light driven metal-free green synthesis of 2-substituted benzimidazole and benzothiazole
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s-Tetrazine based molecules were prepared for visible-light-driven organic transformations. The 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) derivative shows visible light absorption and reversible one-electron reduction behavior. In the presence of pytz and aerial oxygen, aldehyde reacts with o-phenylenediamine or o-aminothiophenol under visible light irradiation at ambient temperature to produce corresponding 2-substituted benzimidazoles and benzothiazoles, respectively. Pytz catalyst demonstrates excellent catalytic activity for alkyl, aryl, organo-metallic substituted aldehydes and reducing sugar. The reaction yield is high for both the electron-donating and electron withdrawing substituents in aromatic aldehydes. The use of a metal-free catalyst and visible light energy, along with the mild reaction conditions, makes this reaction an environmentally benign and energy-saving chemical process.
- Samanta, Suvendu,Das, Sudipto,Biswas, Papu
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p. 11184 - 11193
(2013/12/04)
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- Conventional and microwave-assisted synthesis of benzimidazole derivatives and their in vitro inhibition of human cyclooxygenase
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A large series of 1,2-diaryl-benzimidazole and 2-aryl-1H-benzimidazole derivatives were synthesized with slight differences using both microwave irradiation and conventional heating methods. Usually higher yields and time reactions reduction were obtained
- Secci, Daniela,Bolasco, Adriana,D'Ascenzio, Melissa,Della Sala, Flavio,Yanez, Matilde,Carradori, Simone
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p. 1187 - 1195
(2013/01/15)
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- NMR investigation of hydrogen bonding and 1,3-tautomerism in 2-(2-hydroxy-5-substituted-aryl) benzimidazoles
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The 1,3-tautomerism associated with 2-(2-hydroxy-5-substituted-aryl) benzimidazoles was studied in different solvents. The effect of hydrogen bonding involving the hydroxyl group of the 2-aryl ring on the tautomerism was investigated using NMR spectroscopy. The influence of the solvent concentration on 2-(2-hydroxy-5-chloroaryl)benzimidazole was studied in acetone-d6 and DMSO-d6. Copyright
- Sridharan,Saravanan,Muthusubramanian,Sivasubramanian
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p. 551 - 556
(2007/10/03)
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- Carbonyl and thiocarbonyl compounds XX. Reaction of hydroxybenzaldehydes with o-phenylenediamine; newer aspects in benzimidazole synthesis
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The nature of the products of the uncatalysed reaction of the o-hydroxybenzaldehydes 1a-d with o-phenylenediamine in boiling ethanol is mainly dependent on the molar ratio of the reactants and the nature of the substituents at the phenyl ring of the aldeh
- Latif, N.,Mishriky, N.,Assad, F. M.
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- Reaction of Biologically Active &β-Nitrostyrenes with o-Phenylenediamine: A New Route to the Synthesis of 2-Substituted Benzimidazoles
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β-Nitrostyrenes (1) react with o-phenylenediamine in ethanol to give exclusively 2-substituted benzimidazoles (2) regardless of the nature and position of substituents in the phenyl ring.The correspondnig 2,3-dihydroperimidines (4) are readily obtained by reacting 1,8-diaminonaphthalene with benzaldehydes.Possible routes for the formation of 2 have been discussed.The nitrostyrenes (1) have been found to be toxic to fresh water snails and phytopathogenic fungi in high dilutions.
- Latif, N.,Mishriky, N.,Assad, F. M.,Meguid, S. Abdel
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p. 872 - 874
(2007/10/02)
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