- Synthesis, structures, and luminescence of two 2-D microporous metal-organic frameworks in the zinc (cadmium)-dicarboxylate-imidazolate system
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Two 2-D microporous metal–organic frameworks, [Zn(BDC)(MbIm)]·2DMF (1) and [Cd3(BDC)3(MbIm)2(DMF)2]·2DMF (2), have been synthesized by solvothermal reaction of 1,4-benzenecarboxylic acid (H2BDC) and 2-methylbenzimidazole (MbIm) with zinc/cadmium nitrate. Single-crystal X-ray diffraction analysis indicates that 1 consists of the well-known zinc paddle-wheel motif which is linked by bridging dicarboxylates to form 2-D square grids. The 2-D layers stack offset due to the effect of the spatial structure of MbIm ligand and hydrogen-bonding interaction between MbIm and guest molecules. Similarly, 2 is constructed by six-connected Cd3(μ-O2CR)6(MbIm)2 units and bridging carboxylates, resulting in a 2-D layer structure with triangular grids. Topology analysis reveals that 1 exhibits a 2-D tetragonal plane network with {44·62} topology symbol, while 2 possesses a six-connected {36·46·53} topological network. Analysis of the luminescence spectra demonstrates that the complexes have good luminescent intensities with greater red-shift (82 nm for 1 and 69 nm for 2) corresponding to free MbIm. Elemental analyses, infrared spectra, powder X-ray diffraction, and thermogravimetric analyses of 1 and 2 have been investigated.
- Guo, Xiaoqing,Wang, Miao,Gu, Xuefang,Zhu, Jinli,Tang, Yanfeng,Jiang, Guoqing,Bai, Junfeng
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- Synthesis, crystal structure, and thermal stability of [Mo 2O4(μ2-O)(C6H4O 2)2(H2O)]·(C8H 9N2)2·2H2O
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From hydrothermal treatment of benzene-1,2-diamine, pyrocatechol, and MoO3 in acetic acid solution, a new compound, [Mo2(μ 2-O)2(C6H4O2) 2(H2O)]·(C8H9N 2)2·2H2O (I), constructed from pyrocatechol chelated dinuclear molybdenum units and 2-methylbenzimidazole has been synthesized. Single-crystal structure analysis reveals that the compound crystallizes in the monoclinic space group P21/c with a = 23.365(2), b = 7.2214(5), c = 19.3021(16) β = 97.929(4), V = 3225.6(5), Z = 4, M = 808.46, ρc = 1.665 g/cm3, μ(MoK α) = 0.84 mm-1, F(000) = 1608, the final R = 0.0622 and wR = 0.1484 for 7385 independent reflections with R int = 0.0393. Interestingly, an in situ condensation between acetic acid and benzene-1,2-diamine has occurred, and the unexpected 2-methyl-1-H-benzo[d] imidazoles serve as counterions and N-H donors to form stable hydrogen-bond network in the crystal. Furthermore, intermolecular hydrogen bonds are found among the cations, anions and crystalline water molecules. The double nuclear molybdenum units are connected by O-H.O hydrogen bonds with the crystalline water molecules to form one-dimensional chains, and the chains are further joined together by N-H.O to form a quasi-two dimensional structure.
- Xu
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- 1-(Benzimidazol-2-yl)-1,2-dioxoalkane arylhydrazones and 2-phenylbenzimidazole as the main products of the reactions of 1,2,3-triketone 2-arylhydrazones with o-phenylenediamine
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The reactions of o-phenylenediamine with 1,2,3-triketone 2-arylhydrazones containing alkyl substituents result in the predominant formation of 1-(benzimidazol-2-yl)-1,2-dioxoalkane arylhydrazones, whereas phenyl-substituted analogues afford 2-phenyl-benzi
- Khudina, Ol'ga G.,Murashova, Natal'ya V.,Burgart, Yanina V.,Saloutin, Viktor I.
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- Electroanalytical and computational studies on the corrosion inhibition behavior of ethyl (2-methylbenzimidazolyl) acetate (EMBA) on mild steel in hydrochloric acid
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The interaction and corrosion protection properties of ethyl (2-methylbenzimidazolyl) acetate (EMBA) on mild steel in hydrochloric acid (0.5, 1 and 1.5 M) at different temperatures have been studied by polarization, EIS, adsorption, surface studies, and computational calculations. Polarization studies showed that this molecule act as mixed-type inhibitor. EMBA acts as an effective inhibitor for mild steel in hydrochloric acid at different temperatures (303, 308, and 313 K). At room temperature, EMBA was found to be a more effective inhibitor and its efficiency decreases with increasing temperature. The mechanism involves adsorption of inhibitor molecules on the metal surface and this process obeys the Langmuir isotherm.
- Joseph, Abraham,Mohan, Revathi
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- Synthese et reactivite des 2-phosphonomethylbenzimidazoles n-ethoxycarbonyles: Nouvelle voie d'acces aux 2-phosphonomethyl n-amidobenzimidazoles et aux 2-phosphonomethyl n-hydrazidobenzimidazoles
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A variety of 2-phosphonomethyl N-amidobenzimidazoles and 2-phosphonomethyl N-hydrazidobenzimidazoles has been efficiently synthesized by treatment of 2-phosphonomethyl N-ethoxycarbonylbenzimidazoles respectively with the appropriate primary amines and hydrazines. The structure of these products was confirmed by IR, NMR(1H, 13C, 31P) spectroscopy and mass spectra.
- Harizi, Abdallah,Zantour, Hedi
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- Enhanced Catalytic Properties of Carbon supported Zirconia and Sulfated Zirconia for the Green Synthesis of Benzodiazepines
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This work reports for the first time a new series of promising porous catalytic carbon materials, functionalized with Lewis and Br?nsted acid sites useful in the green synthesis of 2,3-dihydro-1H-1,5-benzodiazepine – nitrogen heterocyclic compounds. Benzodiazepines and derivatives are fine chemicals exhibiting interesting therapeutic properties. Carbon materials have been barely investigated in the synthesis of this type of compounds. Two commercial carbon materials were selected exhibiting different textural properties: i) Norit RX3 (N) as microporous sample and ii) mesoporous xerogel (X), both used as supports of ZrO2 (Zr) and ZrO2/SO42? (SZr). The supported SZr led to higher conversion values and selectivities to the target benzodiazepine. Both chemical and textural properties influenced significantly the catalytic performance. Particularly relevant are the results concerning the non-sulfated samples, NZr and XZr, that were able to catalyze the reaction leading to the target benzodiazepine with high selectivity (up to 80 %; 2 h). These results indicated an important role of the carbon own surface functional groups, avoiding the use of H2SO4. Even very low amounts of SZr supported on carbon reveal high activity and selectivity. Therefore, the carbon materials herein reported can be considered an efficient and sustainable alternative bifunctional catalysts for the benzodiazepine synthesis.
- Godino-Ojer, Marina,Milla-Diez, Leticia,Matos, Inês,Durán-Valle, Carlos J.,Bernardo, Maria,Fonseca, Isabel M.,Pérez Mayoral, Elena
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- Design, synthesis, and evaluation of different scaffold derivatives against NS2B-NS3 protease of dengue virus
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The number of deaths or critical health issues is a threat in the infection caused by Dengue virus, which complicates the situation, as only symptomatic treatment is the current solution. In this regard we have targeted the dengue protease NS2B-NS3 that is responsible for the replication. The series was designed with the help of molecular modeling approach using docking protocols. The series comprised of different scaffolds viz. cinnamic acid analogs (CA1–CA11), chalcone (C1–C10) and their molecular hybrids (Lik1–Lik10), analogs of benzimidazole (BZ1-BZ5), mercaptobenzimidazole (BS1-BS4), and phenylsulfanylmethylbenzimidazole (PS1-PS4). Virtual screening of various natural phytoconstituents was employed to determine the interactions of designed analogs with the residues of catalytic triad in the active site of NS2B-NS3. We have further synthesized the selected leads. The synthesized analogs were evaluated for the cytotoxicity and NS2B-NS3 protease inhibition activity and compared with known anti-dengue natural phytoconstituent quercetin as the standard. CA2, BZ1, and BS2 were found to be more potent and efficacious than the standard quercetin as evident from the protease inhibition assay.
- Ganji, Lata R.,Gandhi, Lekha,Musturi, Venkataramana,Kanyalkar, Meena A.
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p. 285 - 301
(2020/11/19)
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- Discovery of amide-functionalized benzimidazolium salts as potent α-glucosidase inhibitors
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α-Glucosidase inhibitors (AGIs) are used as medicines for the treatment of diabetes mellitus. The α-Glucosidase enzyme is present in the small intestine and is responsible for the breakdown of carbohydrates into sugars. The process results in an increase in blood sugar levels. AGIs slow down the digestion of carbohydrates that is helpful in controlling the sugar levels in the blood after meals. Among heterocyclic compounds, benzimidazole moiety is recognized as a potent bioactive scaffold for its wide range of biologically active derivatives. The aim of this study is to explore the α-glucosidase inhibition ability of benzimidazolium salts. In this study, two novel series of benzimidazolium salts, i.e., 1-benzyl-3-{2-(substituted) amino-2-oxoethyl}-1H-benzo[d]imidazol-3-ium bromide 9a–m and 1-benzyl-3-{2-substituted) amino-2-oxoethyl}-2-methyl-1H-benzo[d] imidazol-3-ium bromide 10a–m were screened for their in vitro α-glucosidase inhibitory potential. These compounds were synthesized through a multistep procedure and were characterized by1H-NMR,13C-NMR, and EI-MS techniques. Compound 10d was identified as the potent α-glucosidase inhibitor among the series with an IC50 value of 14 ± 0.013 μM, which is 4-fold higher than the standard drug, acarbose. In addition, compounds 10a, 10e, 10h, 10g, 10k, 10l, and 10m also exhibited pronounced potential for α-glucosidase inhibition with IC50 value ranging from 15 ± 0.037 to 32.27 ± 0.050 μM when compared with the reference drug acarbose (IC50 = 58.8 ± 0.12 μM). A molecular docking study was performed to rationalize the binding interactions of potent inhibitors with the active site of the α-glucosidase enzyme.
- Ahmad, Matloob,Ashfaq, Usman Ali,Khan, Imran Ahmad,Sultan, Sadia,Zaki, Magdi E. A.
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- Homology modelling, molecular dynamics simulation and docking evaluation of β-tubulin of Schistosoma mansoni
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Schistosomiasis is one of the neglected diseases causing considerable morbidity and mortality throughout the world. Microtubules with its main component, tubulin play a vital role in helminthes including schistosomes. Benzimidazoles represent potential drug candidates by binding β-tubulin. The study aimed to generate a homology model for the β-tubulin of S. mansoni using the crystal structure of O vis aries (Sheep) β-tubulin (PDB ID: 3N2G D) as a template, then different β-tubulin models were generated and two previously reported benzimidazole derivatives (NBTP-F and NBTP-OH) were docked to the generated models, the binding results indicated that both S. mansoni, S. haematobium were susceptible to the two NBTP derivatives. Additionally, three mutated versions of S. mansoni β-tubulin wild-type were generated and the mutation (F185Y) seems to slightly enhance the ligand binding. Dynamics simulation experiments showed S. haematobium β-tubulin is highly susceptible to the tested compounds; similar to S. mansoni, moreover, mutated models of S. mansoni β-tubulin altered its NBTPs susceptibility. Moreover, additional seven new benzimidazole derivatives were synthesized and tested by molecular docking on the generated model binding site of S. mansoni β-tubulin and were found to have good interaction inside the pocket.
- El-Shehabi, Fouad,Mansour, Basem,Bayoumi, Waleed A.,El Bialy, Serry A.,Elmorsy, Mohammad A.,Eisa, Hassan M.,Taman, Amira
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- Cobalt ferrite magnetic nanoparticles as highly efficient catalyst for the mechanochemical synthesis of 2-aryl benzimidazoles
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A highly efficient magnetically separable nano cobalt ferrite catalyst was synthesized via the sol-gel auto combustion method, characterized by powder XRD, SEM, TEM, UV–Visible, FT-IR, magnetic study, and BET isotherm analysis. The synthesized material was found to be an efficient heterogeneous Lewis acid catalyst for the synthesis of 2-aryl benzimidazole derivatives via solvent-free mechanochemical synthesis. The notable features of this new protocol include solvent-free reaction, cost-effectiveness, good yields, and environmental friendliness to afford the products within a short reaction time along with easy recovery and reuse of the nano catalyst.
- Borade, Ravikumar M.,Jadhav, K. M.,Kale, Swati B.,Pawar, Rajendra P.,Tekale, Sunil U.
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- Preparation method 2 -substituted benzimidazole derivative
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The invention belongs to the field of fine chemical product production, and particularly relates to 2 -substituted benzimidazole derivative preparation method which comprises the following steps: (1) taking O-phenylenediamine and aldehyde as raw materials, carrying out catalytic condensation, cyclization and oxidation reaction in a eutectic solvent. (2) Water is added to the reaction system, the separated product is filtered, and the eutectic solvent is recycled. (3) After recrystallization, a target product is obtained. The method has the advantages of simple operation process, easily available raw materials, low cost, high purity of the target product and no catalyst participation, can effectively prevent isomer formation, and is beneficial to large-scale production.
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Paragraph 0029-0034; 0094-0096
(2021/11/10)
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- Application of sulfonic acid fabricated cobalt ferrite nanoparticles as effective magnetic nanocatalyst for green and facile synthesis of benzimidazoles
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This work represents the design and synthesis of efficient sulfonated cobalt ferrite solid acid catalyst. The synthesized solid acid green catalyst was characterized using various techniques viz. FT-IR, powder XRD, SEM, TEM and VSM. The obtained catalyst was used to synthesize biologically significant 2-substituted benzimidazole derivatives by condensation between o-phenylenediamine with various aromatic, aliphatic and heterocyclic aldehydes. High yield (up to 98 %), short reaction time (10?25 min), mild reaction condition, wide functional group tolerance, easy work-up procedure and excellent values of green chemistry metrices such as lower E factor (0.126), high RME value (88.83 %), carbon efficiency (100 %) and high atom economy (AE) value (90.65 %), are some salient features of the present catalytic system. Moreover, the catalyst recovery by simply using an external magnet and catalyst reusability up to 7 times without any significant loss in catalytic efficiency are some additional remarkable features of the current protocol.
- Yadav, Priyanka,Kakati, Praachi,Singh, Preeti,Awasthi, Satish K.
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- Sustainable photocatalytic synthesis of benzimidazoles
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Among the 17 Sustainable Development Goals presented by the United Nations in 2015, great attention is devoted to the production of goods and chemicals by use of renewable raw materials, by recycling of products and by extensive use of renewable energy sources. In this context, photocatalysis attracted great attention for the possibility to exploit Solar light to promote the desired chemical reactions. Besides its use in degradation of pollutants and in the production of fuels, some efforts have been devoted in the development of photocatalytic processes for the synthesis of fine chemicals with high added-value. In this work, we investigated the sustainable photocatalytic synthesis of benzimidazole derivatives through a one-pot, tandem process starting from a nitro compound and ethanol. By a photocatalytic approach, ethanol is dehydrogenated producing the hydrogen required for reduction of nitro groups and the aldehyde required for cyclization and production of the benzimidazole unit. Co-doping of TiO2 with B and N is beneficial to increase the photocatalytic activity in H2 production from ethanol. The effect of various metal co-catalysts (Pt, Pd Ag, Cu) have been evaluated on H2 production rate and on selectivity in the synthesis of substituted benzimidazoles: Pt showed the highest selectivity in the desired products while Pd demonstrated a great activity for hydrodehalogenation, with potential interest for degradation of persistent pollutants.
- Montini, Tiziano,Gombac, Valentina,Delgado, Juan J.,Venezia, Anna Maria,Adami, Gianpiero,Fornasiero, Paolo
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- Enhanced catalytic activity of one-dimensional CdS @TiO2 core-shell nanocomposites for selective organic transformations under visible LED irradiation
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In this study, we are interested in the photocatalytic activity under visible LED irradiation of one- dimensional (1D) CdS @TiO2 core–shell nanocomposites (CSNs) prepared through a facile and convenient method. For the synthesis of 1D CdS@TiO2 core/shell structure, titania source (Tetrabutyl titanate) was hydrolyzed by water vapor transmission on the surface of CdS nanowires (NWs) which were prepared via solvothermal method. The characterization of 1D CdS@TiO2 core–shell nanocomposites (CdS@TiO2 CSNs) was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy, and UV–Vis diffuse reflectance spectroscopy (DRS). The as-synthesized sample was utilized for the selective reduction of nitro compounds to benzimidazole and anilide, and also the reduction of benzophenones to alcohol under blue LED irradiation. The 1D CdS@TiO2 CSNs exhibited enhanced photoactivity compared with the pure TiO2, CdS nanowires and commercial TiO2-P25. The excellent reusability of the photocatalyst was examined for six runs. The results demonstrated that the prepared sample has the potential to provide a promising visible light-driven photocatalyst for other organic transformations.
- Eskandari, Parvin,Kazemi, Foad,Ramdar, Moosa,Zand, Zahra
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- Rhodium catalyzed 2-alkyl-benzimidazoles synthesis from benzene-1,2-diamines and tertiary alkylamines as alkylating agents
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Substituted 2-alkyl-benzimidazoles were synthesized from benzene-1,2-diamine and tertiary amines as alkylating agent under polystyrene supported rhodium (Rh@PS) nanoparticles (NPs) catalyzed conditions. The heterogeneous rhodium catalyst was applied first time for the synthesis of 2-alkyl-benzimidazoles. The reaction followed through oxidation of alkylamines, transamination, and oxidative cyclisation with benzene-1,2-diamines for the corresponding products synthesis with good yields. The process is applicable for vast substrate scope, several functional groups are tolerable, and the Rh@PS catalyst is recyclable up to four cycles without significant loss in catalytic activity.
- Yamini,Sharma, Saurabh,Das, Pralay
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- Visible light initiated oxidative coupling of alcohols ando-phenylenediamines to synthesize benzimidazoles over MIL-101(Fe) promoted by plasmonic Au
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The use of visible light to initiate one-pot synergistic/cascade reactions is a green and energy saving strategy. In this manuscript, we report that MIL-101(Fe) can act as a multifunctional catalyst to realize the oxidative condensation betweeno-phenylenediamines and alcohols to synthesize benzimidazoles under visible light. The deposition of plasmonic Au nanoparticles (Au NPs) on MIL-101(Fe) led to significantly improved activity. Both controlled experiments and electron spin resonance (ESR) results revealed that the production of benzimidazoles fromo-phenylenediamines and alcohols involves three sequential steps,i.e., the oxidative dehydrogenation of alcohols to produce aldehydes, the condensation betweeno-phenylenediamines and the aldehydes to produce Schiff bases and their oxidation to form benzimidazoles,viaa superoxide radical (O2˙?)-mediated pathway. The promoting effect of plasmonic Au NPs in this reaction can be ascribed to the effective transfer of the surface plasmon resonance (SPR)-excited hot electrons to the lowest unoccupied molecular orbital (LUMO) of MIL-101(Fe), which led to the generation of more active O2˙?radicals. This study not only provides a green and sustainable way for the synthesis of benzimidazoles, but also highlights the great potential of using rationally designed plasmonic metal NP/MOF nanocomposites as multifunctional catalysts for light initiated one-pot tandem/cascade reactions.
- Hao, Mingming,Li, Zhaohui,Qin, Yuhuan,Xu, Chao
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p. 4161 - 4169
(2021/06/17)
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- Metal-free oxidative decarbonylative halogenation of fused imidazoles
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An efficient strategy has been developed for the deformylative halogenation of carbaldehyde imidazo-fused heterocycles in the presence of TBHP controlled by temperature. A convenient and sequential functionalization (C8 to C3) portrays the synthetic utility of the current method.N-Heterocycle benzamide products were also observedviathe ring opening of imidazopyridines through the cleavage of C-C bond at high temperatures. Features of this method include temperature-controlled excellent regioselectivity, mild conditions and functional group tolerance.
- Kumar, Gulshan,Shankar, Ravi,Singh, Davinder,Tali, Javeed Ahmad
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p. 20551 - 20555
(2021/11/23)
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- Accelerated microdroplet synthesis of benzimidazoles by nucleophilic addition to protonated carboxylic acids
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We report a metal-free novel route for the accelerated synthesis of benzimidazole and its derivatives in the ambient atmosphere. The synthetic procedure involves 1,2-aromatic diamines and alkyl or aryl carboxylic acids reacting in electrostatically charged microdroplets generated using a nano-electrospray (nESI) ion source. The reactions are accelerated by orders of magnitude in comparison to the bulk. No other acid, base or catalyst is used. Online analysis of the microdroplet accelerated reaction products is performed by mass spectrometry. We provide evidence for an acid catalyzed reaction mechanism based on identification of the intermediate arylamides. Their dehydration to give benzimidazoles occurs in a subsequent thermally enhanced step. It is suggested that the extraordinary acidity at the droplet surface allows the carboxylic acid to function as a C-centered electrophile. Comparisons of this methodology with data from thin film and bulk synthesis lead to the proposal of three key steps in the reaction: (i) formation of an unusual reagent (protonated carboxylic acid) because of the extraordinary conditions at the droplet interface, (ii) accelerated bimolecular reaction because of limited solvation at the interface and (iii) thermally assisted elimination of water. Eleven examples are shown as evidence of the scope of this chemistry. The accelerated synthesis has been scaled-up to establish the substituent-dependence and to isolate products for NMR characterization.
- Basuri, Pallab,Gonzalez, L. Edwin,Morato, Nicolás M.,Pradeep, Thalappil,Cooks, R. Graham
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p. 12686 - 12694
(2020/12/29)
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- Synthesis and antidiabetic evaluation of benzimidazole-tethered 1,2,3-triazoles
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Some novel benzimidazole-tethered 1,2,3-triazole derivatives (4a–r) were synthesized by a click reaction between 2-substituted 1-(prop-2-yn-1-yl)-1H-benzo[d]imidazole and in situ azide. The structures of the synthesized compounds were confirmed by spectroscopic studies (one- and two-dimensional nuclear magnetic resonance, Fourier transform infrared, and high-resolution mass spectra). The synthesized compounds were evaluated for their antidiabetic activity. Compounds 4a–r exhibited a good-to-moderate α-amylase and α-glucosidase inhibitory activity, with IC50 values ranging from 0.0410 to 0.0916 μmol/ml and 0.0146 to 0.0732 μmol/ml, respectively. Compounds 4e, 4g, and 4n were found to be most active. Furthermore, the binding conformation of the most active compounds was ascertained by docking studies.
- Deswal, Laxmi,Verma, Vikas,Kumar, Devinder,Kaushik, Chander?P.,Kumar, Ashwani,Deswal, Yogesh,Punia, Suman
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- Benzimidazole compound with endothelial lipase inhibition effect and application of benzimidazole compound
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The invention discloses a benzimidazole compound with an endothelial lipase inhibition effect and application of the benzimidazole compound, and belongs to the technical field of medicines. The benzimidazole compound has an excellent inhibition effect on endothelial lipase, can effectively treating atherosclerosis and sequelae thereof, such as coronary heart disease, and also promotes treatment onmetabolic syndrome and sequelae thereof, such as diabetes. The benzimidazole compound provided by the invention has good solubility in an aqueous medium, also has good biological activity and metabolic stability, and shows advantages in the aspect of serum stability.
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Paragraph 0097; 0126-0128
(2020/12/09)
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- Cuprous complex containing meta-position carborane ligand as well as preparation method and application of cuprous complex
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The invention relates to a cuprous complex containing a meta-position carborane ligand as well as a preparation method and application of the cuprous complex. The cuprous complex is prepared by the following method: reacting n-BuLi with m-carborane diphenol, then adding 3-chloropyridine for continuous reaction, then adding CuI into a reaction system for continuous reaction, after the reaction is finished, separating the reaction product to obtain the cuprous complex containing the m-carborane ligand, and applying the cuprous complex to one-pot synthesis of the benzimidazole derivative. Compared with the prior art, the method has the advantages that o-phenylenediamine and aldehyde compounds which are cheap and easy to obtain can be used as substrates, the reaction conditions are mild, the universality is good, the catalytic efficiency is high, byproducts are few, the cost is low, products are easy to separate, and generation of a large amount of waste residues is avoided.
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Paragraph 0058-0061
(2020/10/14)
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- A NaH-promoted N-detosylation reaction of diverse p-toluenesulfonamides
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A NaH-mediated detosylation reaction of various Ts-protected indoles, azaheterocycles, anilines and dibenzylamine was reported. The method features cheap reagent, convenient operations, mild reaction conditions and broad substrate scope. Moreover, this study revealed that the loading of NaH in tosylation reactions of nitrogen-containing compounds with NaH as a base in DMA or DMF should be controlled due to the possibility of adverse detosylation.
- Sun, Wanwan,Chen, Xiaobei,Hu, Ying,Geng, Huihui,Jiang, Yuanrui,Zhou, Yuxin,Zhu, Wenjing,Hu, Min,Hu, Haohua,Wang, Xingyi,Wang, Xinli,Zhang, Shilei,Hu, Yanwei
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supporting information
(2020/10/05)
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- Synthesis method of benzimidazole compound based on iron catalytic oxidation-reduction coupling reaction
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The invention belongs to the field of organic synthesis, and relates to a benzimidazole compound synthesis method based on an iron catalytic oxidation-reduction coupling reaction. According to the method, o-nitroaniline compounds and alcohol compounds are used as raw materials, and the benzimidazole compounds are generated through iron-catalyzed redox coupling reaction in the presence of an iron catalyst and a proton donor. The method provided by the invention provides a new way for the synthesis of benzimidazole drugs and pesticides. Compared with a traditional benzimidazole compound synthesis method with o-phenylenediamine compounds and carboxylic acid or carboxylic acid derivatives as raw materials, the method has the advantages that the atom utilization rate of the whole process is increased, the production cost is reduced, and waste gas, waste liquid and waste solid generated in the production process is reduced.
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- Direct synthesis of 2-substituted benzimidazoles: Via dehydrogenative coupling of aromatic-diamine and primary alcohol catalyzed by a Co complex
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A Co(ii) complex with a stable structure was designed and synthesized with quinalic acid and Co (OAc)2·4H2O. The single crystal structure of the complex was characterized by X-ray diffraction. A dehydrogenative coupling of aromatic diamines and primary alcohols was developed by using the Co(ii) complex as the catalyst to synthesize 2-substituted benzimidazole. A series of 2-substituted benzimidazoles were obtained with good to excellent yields under mild reaction conditions. In addition, a compound with inhibitory Parkinson's activity was synthesized on a gram-scale by using this method. Finally, the reaction mechanism was proposed and the energy changes in the reaction process were simulated by density functional theory (DFT).
- Zuo, Minghui,Guo, Weihao,Pang, Yucheng,Guo, Rui,Hou, Chuanfu,Sun, Shouneng,Wu, Hongfeng,Sun, Zhizhong,Chu, Wenyi
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p. 14490 - 14495
(2020/10/03)
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- Flavin Nitroalkane Oxidase Mimics Compatibility with NOx/TEMPO Catalysis: Aerobic Oxidization of Alcohols, Diols, and Ethers
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Biomimetic flavin organocatalysts oxidize nitromethane to formaldehyde and NOx - providing a relatively nontoxic, noncaustic, and inexpensive source for catalytic NO2 for aerobic TEMPO oxidations of alcohols, diols, and ethers. Alcohols were oxidized to aldehydes or ketones, cyclic ethers to esters, and terminal diols to lactones. In situ trapping of NOx and formaldehyde suggest an oxidative Nef process reminiscent of flavoprotein nitroalkane oxidase reactivity, which is achieved by relatively stable 1,10-bridged flavins. The metal-free flavin/NOx/TEMPO catalytic cycles are uniquely compatible, especially compared to other Nef and NOx-generating processes, and reveal selectivity over flavin-catalyzed sulfoxide formation. Aliphatic ethers were oxidized by this method, as demonstrated by the conversion of (-)-ambroxide to (+)-sclareolide.
- Thapa, Pawan,Hazoor, Shan,Chouhan, Bikash,Vuong, Thanh Thuy,Foss, Frank W.
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p. 9096 - 9105
(2020/08/14)
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- Benzimidazoles and benzothiazoles from styrenes and N-vinylimidazole via palladium catalysed oxidative C[dbnd]C and C[sbnd]N bond cleavage
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Herein we report a first, palladium catalyzed, one-pot methodology for the synthesis of pharmacologically important benzimidazoles and benzothiazoles from readily available terminal aromatic olefins. The process involves sequential C[dbnd]C/C[sbnd]N bond cleavage followed by C[sbnd]N/C[sbnd]S bond formation.
- Shaikh, Altab,Ravi, Owk,Pushpa Ragini,Sadhana, Nimma,Reddy Bathula, Surendar
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supporting information
(2019/12/26)
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- Addressing Reversibility of R-NHC Coupling on Palladium: Is Nano-to-Molecular Transition Possible for the Pd/NHC System?
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It has recently been shown that palladium-catalyzed reactions with N-heterocyclic carbene (NHC) ligands involve R-NHC coupling accompanied by transformation of the molecular catalytic system into the nanoscale catalytic system. An important question appeared in this regard is whether such a change in the catalytic system is irreversible. More specifically, is the reverse nano-to-molecular transformation possible? In view of the paramount significance of this question to the area of catalyst design, we studied the capability of 2-substituted azolium salts to undergo the breakage of C-C bond and exchange substituents on the carbene carbon with corresponding aryl halides in the presence of Pd nanoparticles. The study provides important experimental evidence of possibility of the reversible R-NHC coupling. The observed behavior indicates that the nanosized metal species are capable of reverse transition to molecular species. Such an option, known for phosphine ligands, was previously unexplored for NHC ligands. The present study for the first time demonstrates bidirectional dynamic transitions between the molecular and nanostructured states in Pd/NHC systems. As a unique feature, surprisingly small activation barriers (18 kcal/mol) and noticeable thermodynamic driving force (-5 to -7 kcal/mol) were calculated for C-C bond oxidative addition to Pd(0) centers in the studied system. The first example of NHC-mediated Pd leaching from metal nanoparticles to solution was observed and formation of Pd/NHC complex in solution was detected by ESI-MS.
- Denisova, Ekaterina A.,Eremin, Dmitry B.,Gordeev, Evgeniy G.,Tsedilin, Andrey M.,Ananikov, Valentine P.
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p. 12218 - 12227
(2019/09/30)
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- Studies on the synthesis, characterization, cytotoxic activities and plasmid DNA binding of platinum(II) complexes having 2-subsituted benzimidazole ligands
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The aim of this study was to synthesize and evaluate the cytotoxic activities and plasmid DNA interaction of some new platinum(II) complexes, which may have potent cytotoxic activity and low side effects, with benzimidazole derivatives containing some amino acid residues as substituents in their 2 position. Seven 2-subtituted benzimidazole derivatives (1–7) (2-(H, methyl isopropyl, isobutyl, sec-butyl 1H-imidazol-4-ylmethyl or 4-hydroxybenzyl)benzimidazole, respectively), seven platinum(II) complexes with two chlorido leaving groups (1a–7a) and six platinum(II) complexes with an oxalato leaving group (2b–7b) bearing the benzimidazole carrier ligand were synthesized. The chemical structures of the compounds were characterized by their elemental analysis, IR, 1H NMR, and HRMS spectra. The compounds were evaluated for their cytotoxic activities against human HeLa cervical cancer cell lines. The interaction of all the ligands and their complexes with plasmid DNA and their restriction endonuclease reactions with BamHI and HindIII enzymes were investigated by agarose gel electrophoresis. Compounds 1a, 3a, 3b, 6, 7a and 7b, having 2-(H, isopropyl, 1H-imidazol-4-ylmethyl or 4-hydroxybenzyl)benzimidazole carrier ligands, have moderate in vitro cytotoxic activity, close to that of carboplatin.
- Gozelle, Mahmut,Sülo?lu, Aysun K?l??,Selmano?lu, Güldeniz,Ramazano?lu, Nagehan,A??k, Leyla,Gümü?, Fatma
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p. 298 - 308
(2019/02/06)
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- Synthesis and pharmacological screening of new isatin-3-[N2-(benzimidazol-1-acetyl)]hydrazone
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Twenty new isatin-3-[N2-(benzimidazol-1-acetyl)]hydrazones (IV) were synthesized from ten different isatin-3-[N2–(chloroacetyl)] hydrazones (III) by reacting with benzimidazole and 2-methyl benzimidazole. The intermediates were obtained from isatin hydrazones (II) on condensation with chloroacetyl chloride. These compounds were characterized by IR, 1H NMR and mass spectra. All the compounds were screened for antimicrobial, antioxidant and cytotoxic activity. Some of the new compounds showed promising antibacterial and antifungal activity.
- Chaithanya,Kasiviswanath,Prabhakara Chary
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p. 321 - 329
(2019/11/29)
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- Supported Rhodium (Rh@PS) Catalyzed Benzimidazoles Synthesis Using Ethanol/Methanol as C2H3/CH Source
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An effective and stable polystyrene supported rhodium (Rh@PS) nano-catalyst has been synthesized by following reduction-deposition approach and applied for the selective benzimidazoles synthesis from 1,2-phenylenediamines and ethanol/methanol as C2H3/CH source. The ethanol/methanol in the presence of trace amounts of aerobic oxygen under Rh@PS catalysed condition, first participated in oxidation of alcohol followed by consecutive condensation, cyclization and hydrogen elimination reactions with 1,2-phenylenediamine gave the desired products in good yields. The Rh@PS catalyst in a single system performed both oxidation and reduction reactions in a selective/specific manner and applied for large substrate scope. Easy recovery, handling, stability, recyclability of the catalyst and less chance of metal contamination with the products are the added advantages of the process. (Figure presented.).
- Sharma, Saurabh,Sharma, Ajay,Yamini,Das, Pralay
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- Green synthesis of privileged benzimidazole scaffolds using active deep eutectic solvent
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The exploitation and use of alternative synthetic methods, in the face of classical procedures that do not conform to the ethics of green chemistry, represent an ever-present problem in the pharmaceutical industry. The procedures for the synthesis of benzimidazoles have become a focus in synthetic organic chemistry, as they are building blocks of strong interest for the development of compounds with pharmacological activity. Various benzimidazole derivatives exhibit important activities such as antimicrobial, antiviral, anti-inflammatory, and analgesic activities, and some of the already synthesized compounds have found very strong applications in medicine praxis. Here we report a selective and sustainable method for the synthesis of 1,2-disubstituted or 2-substituted benzimidazoles, starting from o-phenylenediamine in the presence of different aldehydes. The use of deep eutectic solvent (DES), both as reaction medium and reagent without any external solvent, provides advantages in terms of yields as well as in the work up procedure of the reaction.
- Gioia, Maria Luisa Di,Cassano, Roberta,Costanzo, Paola,Cano, Natividad Herrera,Maiuolo, Loredana,Nardi, Monica,Nicoletta, Fiore Pasquale,Oliverio, Manuela,Procopio, Antonio
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supporting information
(2019/08/20)
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- Visible-light-induced condensation cyclization to synthesize benzimidazoles using fluorescein as a photocatalyst
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A mild strategy for visible-light-induced synthesis of benzimidazoles was developed using aromatic aldehydes and o-phenylenediamines as substrates. The use of an organic dye, fluorescein, as an innoxious photocatalyst provided a mild and inexpensive catalytic system to synthesize a series of benzimidazoles in moderate to excellent yields. It was originally applied to this system to obtain benzimidazoles. Besides, the catalytic system does not require an additional oxidant or metal which was good for the environment.
- Li, Zhuofei,Song, He,Guo, Rui,Zuo, Minghui,Hou, Chuanfu,Sun, Shouneng,He, Xin,Sun, Zhizhong,Chu, Wenyi
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p. 3602 - 3605
(2019/07/09)
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- Microwave use of amidine compounds in the aqueous phase benzoate synthesis of benzimidazole compounds method
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The invention discloses a microwave the use of amidine compounds in the aqueous phase benzoate synthesis of benzimidazole compounds, in the aqueous phase under microwave conditions adding benzoic amidine compound under alkaline condition [...] into benzimidazole reaction, invention an environment-friendly, the operation is simple, cheap and safe, efficient process for preparing benzimidazole method. Compared with the prior art, this method not only can be applied to a large number of functional groups, the productive rate is high, few by-products, and the operation is simple, safe, low cost, environmental protection; .
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Paragraph 0015
(2019/03/28)
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- Transcriptome analysis predicts mode of action of benzimidazole molecules against Staphylococcus aureus UAMS-1
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Antimicrobial drug resistance is one of the most critical problems that plagued the human race in modern times. Discovery of novel antibiotics is important to counter this threat. Accordingly, herein we have reported the discovery of substituted benzimidazole class of molecules with antimicrobial property (specifically against Staphylococcus aureus). They were initially identified through a random screening and a novel catalytic synthetic strategy was utilized to access them. in vitro screening and phenotypic profiling revealed the antimicrobial nature. De novo transcriptome and gene analyses predicted the putative targets. This work provides a solid foundation for developing the benzimidazoles as a target specific antimicrobial preclinical candidate.
- Chauhan, Deepika,Hati, Santanu,Priyadarshini, Richa,Sen, Subhabrata
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p. 490 - 503
(2019/06/20)
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- A benzimidazole and synthetic method of derivative thereof (by machine translation)
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The present invention provides a benzimidazole and its derivative synthesis method, the method through the imidazole chloride catalyzed O-phenylenediamine cyclized, realizes the multi-functional chain dibasic and imidazole and 2 - substituted benzimidazole synthesis, method is simple and economic, and the practicability is strong. This invention does not have any other catalyst or additive, synthetic method has good functional group tolerance and excellent yield and purity, reaction time is short, and does not need the harsh reaction conditions, is suitable for industrial production. (by machine translation)
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Paragraph 0045; 0047; 0048; 0050; 0051
(2019/02/10)
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- Synthesis and characterization of benzimidazole by using O-phenylenediamine with different aldehydes and carboxylic acids in the presence of ρ-tsOh as a catalyst
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This research paper deals with the synthesis and diagnose of Benzimidazole rings which were have been prepared by using two different methods in which used starting material o-phenylenediamine with different compounds. The first method is with aldehydes such as 4-Chlorobenzaldehyde, 4-N, N-Dimethylbenzaldehyde, and Formaldehyde. The second is with carboxylic acids such as salicylic acid, acetic acid, and butanoic acid. ρ-TSOH has been using as a catalyst in the synthesis methods above and used F.T.I.R and HNMR spectroscopy are used for diagnosing the prepared rings in addition to the physical properties.
- Kadhim, Abdullah Jawad,Kazim, Ali Chazi
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p. 2131 - 2136
(2018/09/13)
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- Synthesis, characterization, antitumor, antibacterial and urease inhibitory activity of a small series of N-tosyl benzimidazoles
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Benzimidazole derivatives exhibited a broad range of biological activities, e.g., antimicrobial, antiviral, anthelmintic, anti-inflammatory, anticancer and as an anti-ulcer/proton pump inhibitor. Keeping in view the large number of reported drugs containing benzimidazole moiety on one hand and sulfonamide on the other hand, a small series of N-tosyl benzimidazoles (4a-e) have been synthesized. The present work describes the synthesis, characterization and bio-evaluation of five new N-tosyl benzimidazoles with the objective to develop new compounds with improved anticancer, antibacterial and urease inhibitory activities. The substituted 1,2-phenylenediamines in the first step were condensed with aliphatic carboxylic acids to synthesize the substituted benzimidazoles. In the second step the tosyl chloride was reacted with substituted benzimidazoles in basic conditions to afford the title N-tosyl benzimidazoles (4a-e). The screening for their antitumor activities was performed against Agrobacterium tumefaciens by following the potato disc tumor assay. The compound (4e) exhibited excellent antitumor activity with IC50 values 474.45μgml-1 compared to other synthesized compounds. Antibacterial activity results revealed that compounds 4d and 4e having methyl and ethyl substitution respectively at the imidazole ring showed excellent zone inhibition against both gram positive and gram negative strains. The urease inhibitory activity results showed that derivative 4e exhibited highest potential to inhibit the urease enzyme compared to all other derivatives. Based upon our investigation it is proposed that compound (4e) may serve as lead structure to design more potent biological active compounds having multitargets inhibition activities.
- Rashid, Naghmana,Kiran, Almas,Ashraf, Zaman,Bhatti, Moazzam Hussain,Mirza, Bushra,Ismail, Hammad,Rafiq, Muhammad,Jasinski, Jerry P.
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p. 366 - 374
(2018/06/06)
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- Novel purine benzimidazoles as antimicrobial agents by regulating ROS generation and targeting clinically resistant Staphylococcus aureus DNA groove
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A novel series of purine benzimidazole hybrids were designed and synthesized for the first time with the aim to circumvent the increasing antibiotic resistance. Hexyl appended hybrid 3c gave potent activities against most of the tested bacteria and fungi especially against multidrug-resistant strains Staphylococcus aureus (MIC = 4 μg/mL). Structure-activity relationships revealed that the benzimidazole fragment at the 9-position of purine played an important role in exerting potentially antibacterial activity. Both cell toxicity and ROS generation assays indicated that the purine derivative 3c showed low cytotoxicity and could be used as a safe agent. Molecular modeling suggested that hybrid 3c could bind with the residues of Topo IA through hydrogen bonds and electrostatic interactions. Quantum chemical studies were also performed on the target compound 3c to understand the structural features essential for activity. The active molecule 3c could effectively interact with S. aureus DNA to form 3c–DNA complex through groove binding mode, which might block DNA replication to display their powerful antimicrobial activity.
- Wang, Ya-Nan,Bheemanaboina, Rammohan R. Yadav,Cai, Gui-Xin,Zhou, Cheng-He
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supporting information
p. 1621 - 1628
(2018/03/29)
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- An efficient NaHSO3-promoted protocol for chemoselective synthesis of 2-substituted benzimidazoles in water
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An efficient protocol for chemoselective synthesis of 2-substituted benzimidazoles from a variety of aliphatic/aromatic/ heteroaryl aldehydes and o-phenylenediamine derivatives promoted by NaHSO3 in water had been developed. The amount of NaHSO3 had a great effect on the reaction selectivity of 2-substituted benzimidazole and 1,2-disubstituted benzimidazole when the reaction was carried out in water. When the amount of the NaHSO3 was more than 11 equivalents, the 2-substituted benzimidazole could be highly selectively formed as the sole product. NaHSO3 was firstly reacted with aldehyde to form the aldehyde sodium bisulfite, which reacted with o-phenylenediamine to form the 2-substituted benzimidazole and inhibited the formation of 1,2-disubstituted benzimidazole. This protocol solved the poor selectivity problem appearing in traditional method when cyclocondensation between o-phenylenediamine and aldehydes. The method also had advantage of simple work up by filtrating the single 2-substituted benzimidazole precipitates from reaction mixture at the end of the reaction without further purification. In addition, the method was applicable to both electron-rich and electron-poor starting materials, which was successfully used for synthesizing nine novel 2-substituted benzimidazole derivatives containing a 1,2,3-triazole moiety. They were characterized by NMR, IR and HRMS spectrum. Moreover, this method had been applied to a large scale synthesis of 2-substituted benzimidazole derivatives.
- Jiang, Yu-Qin,Jia, Shu-Hong,Li, Xi-Yong,Sun, Ya-Min,Li, Wei,Zhang, Wei-Wei,Xu, Gui-Qing
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p. 1265 - 1276
(2019/01/28)
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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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- Sodium dichloroiodate promoted C-C bond cleavage: An efficient synthesis of 1,3-Benzazoles via condensation of o -amino/mercaptan/hydroxyanilines with β -diketones
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An efficient aqueous sodium dichloroiodate (NaICl 2) mediated protocol is developed for the synthesis of benzofused azoles by the cyclization of 2-amino anilines/thiophenols/phenols with β-diketone compounds. The reactions gave moderate to good yield of the corresponding 2-substituted benzimidazoles/benzothiazoles/benzoxazoles under mild conditions. This tandem process involved a C-C bond cleavage and C-N bond formation. Graphical Abstract?: SYNOPSIS A facile and single protocol for the synthesis of three versatile 1,3-benzazoles viz 2-substituted 1H-benzimidazoles, benzoxazoles and benzothiazoles from readily available starting materials, 1,3-diketones and corresponding o-amino anilines/thiophenols/phenols, by aqueous sodium dichloroiodate (NaICl 2) mediated C—C bond cleavage has been developed. The reaction provides a rapid access to these 1, 3-benzazoles in good yields, thus speeding up the drug discovery process.[Figure not available: see fulltext.].
- Bhagat, Saket B,Ghodse, Shrikant M,Telvekar, Vikas N
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- A continuous compound benzene and imidazole compounds
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The invention discloses a method for continuously synthesizing a benzimidazole compound. The method comprises the steps:in a fixed bed reactor, firstly reducing and activating a loaded multi-metal solid catalyst by hydrogen; then using inert gas as carrier gas; adjusting the temperature to 130-250 DEG C and the pressure at 2-10 MPa; continuously introducing mixed raw materials of an ortho-nitroaniline compound shown in a formula (I), fatty alcohol shown in a formula (II) and distilled water iknto the fixed bed reactor by using a high pressure pump; feeding the reactants which are cooled by a condenser to a gas-liquid separator to collect a liquid product so as to obtain the benzimidazole compound shown in a formula (III), wherein the loaded multi-metal solid catalyst is a Cu-Pd-M/Al2O3 catalyst. According to the method disclosed by the invention, multiple intermittent reactions are changed to a one-step continuous reaction, so that the production process is simplified, generation of byproducts is reduced, the conversion rate can reach 100% to the maximum extent, and the yield of the target product benzimidazole compound can reach 99% to the maximum extent. The formulae are shown in the description.
- -
-
Paragraph 0052-0057; 0060-0061
(2018/06/07)
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- Nanoporous TiO2 containing an ionic liquid bridge as an efficient and reusable catalyst for the synthesis of: N, N ′-diarylformamidines, benzoxazoles, benzothiazoles and benzimidazoles
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In this work, a green and efficient procedure is reported for the preparation of N,N'-diarylformamidines, benzoxazoles, benzothiazoles, and benzimidazoles using nanoporous TiO2 containing an ionic liquid bridge. This reagent is prepared via the modification of nanoporous TiO2 with bis-3-(trimethoxysilylpropyl)-ammonium hydrogen sulfate (TiO2-[bip]-NH2+ HSO4-). The procedure gave the products in excellent yields in very short reaction times under solvent-free conditions. The reusability of the catalyst is the other important feature of the reported method.
- Mazloumi,Shirini,Goli-Jolodar,Seddighi
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p. 5742 - 5752
(2018/04/23)
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- Oxone-mediated annulation of 2-aminobenzamides and 1,2-diaminobenzenes with: Sec -amines via imine- N -oxides: New syntheses of 2,3-dihydroquinazolin-4(1 H)-ones and 1 H -benzimidazoles
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An efficient and mild method for the preparation of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles by the oxone-mediated reaction of sec-amines via imine-N-oxides with 2-amino-N-substituted benzamides and 1,2-diaminobenzenes respectively in THF-wa
- Sriramoju, Vinodkumar,Kurva, Srinivas,Madabhushi, Sridhar
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supporting information
p. 3188 - 3191
(2018/03/06)
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- Oxalic/malonic acids as carbon building blocks for benzazole, quinazoline and quinazolinone synthesis
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An oxidant, base and metal free methodology has been developed for the synthesis of various 2-substituted and non-substituted benzazoles, quinazolines and quinazolinones using oxalic/malonic acids as an in situ carbon source. This methodology is applicable for a wide range of substituted o-phenylenediamine, o-aminothiophenol, o-aminophenol and o-aminobenzamide containing various functional groups and provides good to excellent yields of the corresponding product. Furthermore an easy workup procedure, high yield and easy isolation of products are key features of this methodology. The developed protocol is also applicable for the gram scale synthesis of benzimidazoles.
- Sharma, Saurabh,Bhattacherjee, Dhananjay,Das, Pralay
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supporting information
p. 1337 - 1342
(2018/03/06)
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- I2/TBHP promoted oxidative C–N bond formation at room temperature: Divergent access of 2-substituted benzimidazoles involving ring distortion
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A new ‘one pot’ tandem synthesis of 2-substituted benzimidazoles has been developed from 2-aminobenzyl alcohol/2-aminobenzamide and different coupling partners (nitriles, aldehydes and 1,3-diketones) via iodine and TBHP promoted oxidative ring contraction. The present strategy involves sequential C–N bond formation, cyclization, subsequent ring contraction and dehydrogenation to afford various medicinally important benzimidazole derivatives in moderate to good yields. This operationally simple synthetic approach proceeds at room temperature under base-free condition, broadly applicable to a wide array of nitriles and aldehydes bearing oxidation prone functional groups and noteworthy to mention that various acyclic 1,3-diketones undergo selective C–C bond cleavage leading to 2-alkyl benzimidazoles under mild condition.
- Saha, Moumita,Das, Asish R.
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supporting information
p. 2520 - 2525
(2018/05/31)
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- Access to 1: H -indazoles, 1 H -benzoindazoles and 1 H -azaindazoles from (het)aryl azides: A one-pot Staudinger-aza-Wittig reaction leading to N-N bond formation?
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The synthesis of various substituted 1H-indazoles is reported through N-N bond formation from an iminophosphorane derivative. Supported by control experiments, an original Staudinger-aza-Wittig tandem mechanism is proposed for this transformation.
- Alaime,Daniel,Hiebel,Pasquinet,Suzenet,Guillaumet
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p. 8411 - 8414
(2018/08/06)
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- Imidazolium chloride-catalyzed synthesis of benzimidazoles and 2-substituted benzimidazoles from o-phenylenediamines and DMF derivatives
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A facile, general, and economical synthesis of diversely functionalized benzimidazoles and 2-substituted benzimidazoles has been realized via the imidazolium chloride-catalyzed cyclization of o-phenylenediamines with DMF derivatives. This protocol shows a broad substrate scope for aliphatic, aromatic, and heteroaromatic amides. A series of benzimidazoles and 2-substituted benzimidazoles have been obtained in moderate to excellent yields.
- Gan, Zongjie,Tian, Qingqiang,Shang, Suqin,Luo, Wen,Dai, Zeshu,Wang, Huajun,Li, Dan,Wang, Xuetong,Yuan, Jianyong
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p. 7450 - 7456
(2018/11/27)
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- Synthesis and antimicrobial activity of some benzimidazole and 2-methylbenzimidazole derivatives
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In the present work, benzimidazole and 2-methylbenzimidazole derivatives were synthesized and evaluated for antimicrobial activity against Escherichia coli (Gram-negative bacteria), Staphylococcus aureus (Gram-positive bacteria) and Candida albicans (fungal stain). The structure of the synthesized compounds was confirmed by FTIR, 1H NMR and mass spectroscopy. Antimicrobial activity of all the synthesized compounds was carried out by Broth dilution method to determine MIC value. Compounds P2, P7 and P10 showed better antibacterial activity against Escherichia coli as compared to benzimidazole, 2-methylbenzimidazole and ampicillin. Compounds P8 and P12 showed better antibacterial activity against Staphylococcus aureus as compared to benzimidazole, 2-methylmenzimidazole and ampicillin. Compound P2 and P9 showed better antifungal activity against Candida albicans as compared to benzimidazole, 2-methylbenzimidazole and griseofulvin.
- Jain,Tiwari
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p. 838 - 842
(2017/02/10)
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- Phosphorous acid functionalized polyacrylonitrile fibers with a polarity tunable surface micro-environment for one-pot C-C and C-N bond formation reactions
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The preparation and application of fiber catalysts have attracted much attention. However, research on the effect of the micro-environment of fiber catalysts on the catalytic activities though of special importance is limited. In this work, a novel strategy for the synthesis of phosphoric acid-functionalized polyacrylonitrile fibers with a polarity tunable surface micro-environment by hydrophobic groups for one-pot C-C and C-N bond formation reactions is reported. The special hydrophobic surface micro-environment of the fiber catalysts is proven to promote the catalytic activities impressively in cyclocondensation of β-ketoesters with 2-aminobenzamides, the Knoevenagel condensation as well as the multi-component Biginelli reactions in green solvents. Both the surface synergy of the catalytic sites and hydrophobic auxiliary groups (benzyl or n-butyl) in the surface of fiber catalysts and interface acceleration in reaction medium play an important role in the highly efficient promotion of catalytic activity. Thereby a surface synergistic mechanism is proposed to explain the micro-environment effect. In addition, the fiber catalysts could be simply separated from the reaction system using tweezers and directly used in the next cycle without further treatment. Importantly, even after 10 reaction cycles in water or ethanol, there is no significant loss in their catalytic activity. The results indicate that the phosphoric acid functionalized fibers show green and sustainable potential for industrial production.
- Xu, Gang,Wang, Lu,Li, Mengmeng,Tao, Minli,Zhang, Wenqin
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supporting information
p. 5818 - 5830
(2017/12/26)
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- Synthesis of benzimidazoles from o-phenylenediamines and DMF derivatives in the presence of PhSiH3
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A simple approach to preparation of benzimidazoles from o-phenylenediamines and DMF derivatives, only employing PhSiH3 as promoter without any other additives, was reported. This route provided moderate to high yields with a broad substrate scope. A plausible mechanism for the reaction is proposed based on the spectroscopic characterization (e.g., HRMS and 1H NMR) of the reaction mixture.
- Zhu, Jianhua,Zhang, Zhenbei,Miao, Chengxia,Liu, Wei,Sun, Wei
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p. 3458 - 3462
(2017/05/31)
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- Design and Performance Validation of a Conductively Heated Sealed-Vessel Reactor for Organic Synthesis
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A newly designed robust and safe laboratory scale reactor for syntheses under sealed-vessel conditions at 250 °C maximum temperature and 20 bar maximum pressure is presented. The reactor employs conductive heating of a sealed glass vessel via a stainless steel heating jacket and implements both online temperature and pressure monitoring in addition to magnetic stirring. Reactions are performed in 10 mL borosilicate vials that are sealed with a silicone cap and Teflon septum and allow syntheses to be performed on a 2-6 mL scale. This conductively heated reactor is compared to a standard single-mode sealed-vessel microwave instrument with respect to heating and cooling performance, stirring efficiency, and temperature and pressure control. Importantly, comparison of the reaction outcome for a number of different synthetic transformations performed side by side in the new device and a standard microwave reactor suggest that results obtained using microwave conditions can be readily mimicked in the operationally much simpler and smaller conventionally heated device.
- Obermayer, David,Znidar, Desiree,Glotz, Gabriel,Stadler, Alexander,Dallinger, Doris,Oliver Kappe
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p. 11788 - 11801
(2016/12/09)
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- Ball milling assisted solvent and catalyst free synthesis of benzimidazoles and their derivatives
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Benzoic acid and o-phenylenediamine efficiently reacted under the green solvent-free Ball Milling method. Several reaction parameters were investigated such as rotation frequency; milling balls weight and milling time. The optimum reaction condition was milling with 56.6 g weight of balls at 20 Hz frequency for one hour milling time. The study was extended for synthesis of a series of benzimidazol-2-one or benzimidazol-2-thione using different aldehydes; carboxylic acids; urea; thiourea or ammonium thiocyanate with o-phenylenediamine. Moreover; the alkylation of benzimidazolone or benzimidazolthione using ethyl chloroacetate was also studied.
- El-Sayed, Taghreed H.,Aboelnaga, Asmaa,Hagar, Mohamed
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