- Zwitterions as intermediates in 1,3-dipolar cycloadditions of electrophilic azides to 2-alkylidenetetrahydroimidazoles and 2-alkylidenedihydrobenzimidazoles
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Cyclic ketene N,N-acetals derived from imidazolidine (4a, c) and 2,3-dihydrobenzimidazole (6a-c) add methanesulphonyl azide (2 a) or picryl azide (2f) to afford the zwitterions 5 and 7, respectively. The structure of 7d is elucidated by X-ray crystallography. Reversibility of formation and thermal stability of the N-sulphonyl zwitterions depend on the substitution pattern at the carbon atom to which the triazenide moiety is attached: In the case of a pair of geminal methyl groups (5a, 7a) formation is irreversible and decomposition by cyclisation and subsequent reactions occurs above -20°C, while in presence of a single alkyl group (7c, d) these processes require heating to 80°C and are accompanied by partial reversion to 2a and ketene N,N-acetals (6b, c). Cyclisation of the zwitterions yields intermediate spirocyclic [3 + 2] cycloadducts, which may undergo [3 + 2] cycloreversion into N-sulphonylimine 13 and diazo compound 14 or extrude molecular nitrogen to furnish ring-expanded 2-(sulphonyl-imino)piperazine derivatives (9, 11). VCH Verlagsgesellschaft mbH, 1996.
- Quast, Helmut,Ach, Manfred,Ivanova, Svetlana,Peters, Eva-Maria,Peters, Karl,Von Schnering, Hans Georg
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- Crystal structures and spectroscopic properties of copper(II)–dipicolinate complexes with benzimidazole ligands
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The syntheses, crystal structures and spectroscopic properties of three Cu(II)–dipicolinate complexes with benzimidazole ligands, namely [Cu(bzim)(dipic)(MeOH)] (1), [Cu2(2-Etbzim)2(dipic)2]n·0.5nH2O (2) and [Cu2(2-iPrbzim)2(dipic)2]n (3), where dipic = dipicolinate, bzim = 1-H-benzimidazole, 2-Etbzim = 2-ethyl-1-H-benzimidazole and 2-iPrbzim = 2-isopropyl-1-H-benzimidazole, are reported. Crystal structure studies revealed different coordination modes of the dipicolinate ligands; tridentate chelating for monomeric complex 1, and both tridentate chelating and bridging for similar polymeric complexes 2 and 3. Polymers 2 and 3 both contain two units, in which the Cu(II) central atoms Cu1 and Cu2 have different coordination polyhedra. The first unit {Cu(dipic)2} with Cu1 is connected to the second via two bidentate carboxylate groups of an μ3-bridging dipicolinate. In the second unit, Cu2 is coordinated by two imidazole nitrogen atoms from 2-ethyl-1-H-benzimidazole (2) or 2-isopropyl-1-H-benzimidazole (3) ligands. Complex 2 is of higher symmetry and has a localized Cu(II) atom Cu2 in a special position on the twofold axis. EPR spectra of all three Cu(II) complexes, which were measured at both room temperature and 98?K, indicate distorted tetragonal coordination spheres for all the Cu(II) atoms. The g-factor relation (g//> g┴ > 2.0023) is consistent with a dx2-y2 ground electronic state in each case.
- Masárová, Petra,Kuchtanin, Vladimír,Mazúr, Milan,Moncol, Ján
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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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- Zeolite-catalyzed environmentally friendly synthesis of benzimidazole derivatives
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A simple and environmentally friendly synthesis of substituted benzimidazoles was developed using a small-pore-size zeolite. The similar reaction was not applicable to the preparation of 2-substituted imidazolines. Copyright Taylor & Francis Group, LLC.
- Hegedues, Adrienn,Hell, Zoltan,Potor, Attila
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- The Transition Metal-catalyzed N-Heterocyclization. A Reductive Trasformation of Aminonitroarenes and Dinitroarenes into Phenanthroline Derivatives Using Aliphatic Aldehydes under Carbon Monoxide Pressure
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The Catalytic N-heterocyclization of aminoarenes and dinitroarenes using aliphatic n-C3-C5 aldehydes was carried out at 180 deg C under the pressure of carbon monoxide (70 atm at room temperature) in the presence of RhCl(PPh3)3 and PdCl2 as a binary catalyst system.The reaction of p-nitroaniline with propanal, butanal, and pentanal gave 3,8-diethyl-2,9-dimethyl-4,7-phenanthroline, 2,9-diethyl-3,8-dipropyl-4,7-phenanthroline, and 3,8-dibutyl-2,9-dipropyl-4,7-phenantroline in 43, 57, and 54percent yields respectively.On the other hand, m-nitroaniline and o-nitroaniline gave 1,7-phenanthroline and imidazole derivatives in rather low yields (21 and 24percent) under the reaction conditions employed.
- Watanabe, Yoshihisa,Suzuki, Naoki,Tsuji, Yasushi
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- Rapid one-pot preparation of 2-substituted benzimidazoles from esters using microwave conditions
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A high-yielding one-pot procedure for the generation of 2-substituted benzimidazoles first from esters using a microwave procedure is described. Copyright Taylor & Francis Group, LLC.
- Jing, Xiaobi,Zhu, Qihua,Xu, Feng,Ren, Xinfeng,Li, Dong,Yan, Chaoguo
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- A green chemical synthesis of 2-alkylbenzimidazoles from 1,2-phenylenediamine and propylene glycol, or alcohols mediated by Ag-TiO 2/clay composite photocatalyst
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Benzimidazole derivatives were synthesized in good yield from 1,2-phenylenediamine (PD) and various alcohols by photocatalytic cyclization with TiO2 /acidic clay composite catalyst using UV-A and solar light. Doping silver on TiO2 enhances product yield and selectivity of the photocatalytic synthesis of benzimidazoles. The higher efficiency of nano-Ag-doped TiO2 in solar light makes this synthesis a green chemical process. Copyright
- Selvam,Swaminathan
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- An efficient one-pot synthesis of condensed imidazoles using pentafluorophenylammonium triflate as novel, metal-free and reusable catalyst
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A superior method of synthesis of condensed imidazoles by the catalytic action of pentafluorophenylammonium triflate on the reaction of 1,2-diaminoaromatics with orthoesters is described. The catalyst is reusable and can be applied several times without considerable decrease in the yields and rates of the reaction.
- Montazeri, Naser,Esmaeili, Abbas
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- Improved Phenoxyalkylbenzimidazoles with Activity against Mycobacterium tuberculosis Appear to Target QcrB
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The phenoxy alkyl benzimidazoles (PABs) have good antitubercular activity. We expanded our structure-activity relationship studies to determine the core components of PABs required for activity. The most potent compounds had minimum inhibitory concentrations against Mycobacterium tuberculosis in the low nanomolar range with very little cytotoxicity against eukaryotic cells as well as activity against intracellular bacteria. We isolated resistant mutants against PAB compounds, which had mutations in either Rv1339, of unknown function, or qcrB, a component of the cytochrome bc1 oxidase of the electron transport chain. QcrB mutant strains were resistant to all PAB compounds, whereas Rv1339 mutant strains were only resistant to a subset, suggesting that QcrB is the target. The discovery of the target for PAB compounds will allow for the improved design of novel compounds to target intracellular M. tuberculosis.
- Chandrasekera, N. Susantha,Berube, Bryan J.,Shetye, Gauri,Chettiar, Somsundaram,O'Malley, Theresa,Manning, Alyssa,Flint, Lindsay,Awasthi, DIvya,Ioerger, Thomas R.,Sacchettini, James,Masquelin, Thierry,Hipskind, Philip A.,Odingo, Joshua,Parish, Tanya
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- Benzimidazoles: Oxydation heterocyclisante par le nitrobenzene ou le dimethylsulfoxyde sur silice et sous irradiation micro-ondes ou ultra-violet
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The oxidative heterocyclisation of aldehydes and o-phenylenediamine with nitrobenzene or dimethylsulfoxide impregnated on silica gel and irradiated with microwaves affords benzimidazoles in good yields and high purity. When UV irradiation is used as an energy source, the reaction is very slow.
- Ben-Alloum, Abdelkrim,Bakkas, Salem,Soufiaoui, Mohamed
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- Density functional treatment and electro analytical measurements of liquid phase interaction of 2-ethylbenzimidazole (EBI) and ethyl (2-ethylbenzimidazolyl) acetate (EEBA) on mild steel in hydrochloric acid
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DFT calculations on the liquid phase interaction and corrosion inhibition properties of 2-ethylbenzimidazole (EBI) and its derivative ethyl (2-ethylbenzimidazolyl)acetate (EEBA) on mild steel in hydrochloric acid (0.5, 5 and 1.5 M) at three different temperatures (303, 308 and 313 K) have been studied using EIS, polarization, adsorption measurements and computational calculations. Results show that EBI and EEBA act as effective inhibitors for the corrosion of mild steel in hydrochloric acid media. Polarization studies showed that both the inhibitors behave as mixed type inhibitors with respect to the electrode reactions. EEBA offers better inhibition efficiency than EBI. The inhibition efficiency found to decrease with increase in temperature in either of the cases. The mechanism involves adsorption phenomenon and in the case of EEBA, the adsorption obeyed Langmuir adsorption isotherm. For EBI, the adsorption obeyed Langmuir adsorption isotherm except for 313 K in 1.5 M HCl, for which the best fit adsorption isotherm was Temkin adsorption isotherm.
- Mohan, Revathi,Ramya,Anupama,Joseph, Abraham
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- STEREOCHEMISTRY IN TRIVALENT NITROGEN COMPOUNDS. 40. TORSIONAL BARRIERS IN N-2,4-DINITROBENZENESULFENYLBENZIMIDAZOLES.
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N-2,4-Dinitrobenzenesulfenylbenzimidazoles exhibit substantial barriers to torsion about the sulfur-nitrogen bond (ca 19 kcal/mole).
- Raban, Morton,Chang, Hu,Craine, Leslie H.
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- Ammonium sulphate-magnesium selective reduction of N-2-nitrophenylimidates: Synthesis of 2-substituted benzimidazoles
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Various N-2-nitrophenylimidates were selectively reduced by (NH4)2SO4-Mg to the non-isolated N-2-aminophenylimidates which cyclise to the corresponding 2-substituted benzimidazoles.
- Harizi, Abdallah,Zantour, Hedi
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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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- Simple inorganic base promoted C-N and C-C formation: synthesis of benzo[4,5]imidazo[1,2-a]pyridines as functional AIEgens used for detecting picric acid
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Metal-free catalyzed intermolecular tandem Michael addition/cyclization has been developed for the synthesis of benzo[4,5]imidazo[1,2-a]pyridines from α-bromocinnamaldehyde and 2-substituted benzimidazoles. The reaction promoted by a simple inorganic base displays moderate to good yields and good functional group tolerance. The optical properties of some typical products have been investigated. We found that, due to the presence of the benzene ring at the C1-position of benzo[4,5]imidazo[1,2-a]pyridines which restricts intramolecular motion, as a new type of aggregation-induced emission (AIE) luminogen (AIEgen), they show very good solid-state fluorescence with quantum yields up to 88.80%. Importantly, the AIE performance of compound3bcan be useful to detect the nitroaromatic explosive picric acid (PA) with a detection limit and quenching constant of 42.5 nM and 7.27 × 104M?M, respectively.
- Yang, Kai,Luo, Shi-He,Chen, Si-Hong,Cao, Xi-Ying,Zhou, Yong-Jun,Lin, Yan-Lan,Huo, Yan-Ping,Wang, Zhao-Yang
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supporting information
p. 8133 - 8139
(2021/10/04)
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- s-Tetrazine-functionalized hyper-crosslinked polymers for efficient photocatalytic synthesis of benzimidazoles
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Developing green-safe, efficient and recyclable catalysts is crucial for the chemical industry. So far, organic photocatalysis has been proved to be an environmentally friendly and energy-efficient synthetic technology compared with traditional metal catalysis. As a versatile catalytic platform, hyper-crosslinked polymers (HCPs) with large surface area and high stability are easily prepared. In this report, we successfully constructed two porous HCP photocatalysts (TZ-HCPs) featurings-tetrazine units and surface areas larger than 700 m2g?1through Friedel-Crafts alkylation reactions. The rational energy-band structures and coexisting micro- and mesopores endow TZ-HCPs with excellent activities to realize the green synthesis of benzimidazoles (28 examples, up to 99% yield, 0.5-4.0 h) in ethanol. Furthermore, at least 21 iterative catalytic runs mediated by TZ-HCP1D were performed efficiently, with 96-99% yield. This study of TZ-HCPs sheds light on the wide-ranging prospects of application of HCPs as metal-free and green photocatalysts for the preparation of fine chemicals.
- An, Wan-Kai,Zheng, Shi-Jia,Zhang, Hui-Xing,Shang, Tian-Tian,Wang, He-Rui,Xu, Xiao-Jing,Jin, Qiu,Qin, Yuchen,Ren, Yunlai,Jiang, Song,Xu, Cui-Lian,Hou, Mao-Song,Pan, Zhenliang
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supporting information
p. 1292 - 1299
(2021/02/26)
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- Fluorinated phosphoric acid as a versatile effective catalyst for synthesis of series of benzimidazoles, benzoxazoles and benzothiazoles at room temperature
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The present work describes synthesis of a series of benzimidazoles, benzoxazoles and benzothiazoles through the cyclization of 1, 2-phenylenediamine, 2-aminothiophenol, or 2-aminophenol with aryl, aliphatic and heteroaryl aldehydes. The present synthetic protocol is very much efficient in presence of 5 mol % fluorophosphoric acid as a catalyst in ethanol solvent at room temperature. Shorter reaction time, simple work-up technique, high yields and easy availability are specific compensations of the present synthetic approach.
- Mathapati, Sushil R.,Patil, Komal N.,Mathakari, Sujit S.,Suryawanshi, Appasaheb W.,Jadhav, Arvind H.
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p. 538 - 547
(2021/01/21)
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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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- 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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- Preparation method of Gboxin
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The invention relates to a preparation method of Gboxin. The method comprises the following steps: reacting o-phenylenediamine with n-propanal; preparing 2-ethyl-1H-benzimidazole, carrying out N-alkylation reaction on 2-ethyl-1H-benzimidazole and chloroacetic acid-L-menthyl ester to generate 2-(2-ethyl-1H-benzimidazole) L-menthyl acetate, carrying out methylation by using iodomethane to generate abenzimidazolium salt, and finally, exchanging iodine ions into chloride ions by using chlorine ion exchange resin to obtain the final product Gboxin. The method has the advantages of short process route, mild conditions, simple operation and low equipment requirements, and the obtained product has the advantages of high purity and high yield, and is suitable for industrial production.
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Paragraph 0022; 0031; 0034-0035; 0043; 0046-0047; 0054
(2020/08/27)
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- Metal-organic framework mediated expeditious synthesis of benzimidazole and benzothiazole derivatives through an oxidative cyclization pathway
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Herein, we report the facile synthesis of various benzimidazoles and benzothiazoles by using the NH2-MIL-125(Ti) MOF as an efficient oxidant-free heterogeneous catalyst with good yield. Adsorption of the substrate on the NH2-MIL-125(Ti) MOF surface through electron deficient Ti4+ sites initiates the reaction. The broad substrate scope and high reusability of this catalyst are attractive for synthesis of a wide range of medicinally active benzimidazole and benzothiazole derivatives.
- Sankar, Velayudham,Karthik, Peramaiah,Neppolian, Bernaurdshaw,Sivakumar, Bitragunta
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p. 1021 - 1027
(2020/01/31)
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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 0016
(2019/03/28)
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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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- A novel ternary GO@SiO2-HPW nanocomposite as an efficient heterogeneous catalyst for the synthesis of benzazoles in aqueous media
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A new solid acid catalyst, consisting of 12-phosphotungstic heteropoly acid (HPW) supported on graphene oxide/silica nanocomposite (GO@SiO2), has been developed via immobilizing HPW onto an amine-functionalized GO/SiO2 surface through coordination interaction (GO@SiO2-HPW). The GO@SiO2-HPW nanocomposite was characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and powder X-ray diffraction (XRD). The prepared nanocomposite could be dispersed homogeneously in water and further used as a heterogeneous, reusable, and efficient catalyst for the synthesis of benzimidazoles and benzothiazoles by the reaction of 1,2-phenelynediamine or 2-aminothiophenol with different aldehydes.
- Habibzadeh, Setareh,Firouzzadeh Pasha, Ghasem,Tajbakhsh, Mahmood,Amiri Andi, Nasim,Alaee, Ehsan
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p. 934 - 944
(2019/06/13)
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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; 0052; 0053
(2019/02/10)
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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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- 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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- 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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- A novel synthesis of 2-arylbenzimidazoles in molecular sieves-MeOH system and their antitubercular activity
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Arylbenzimidazoles have been synthesized as antimycobacterial agents. An efficient synthesis has been developed for 2-arylbenzimidazoles from o-phenylenediamines and aromatic aldehydes in molecular sieves-methanol system. The methodology is straightforward to get 2-arylbenzimidazoles (3a–3z) in excellent yields with high chemoselectivity over 2-aryl-1-benzylbenzimidazoles (4a–4z). All these benzimidazole analogues were evaluated against M. tuberculosis in BACTEC radiometric assay. The compounds 4y and 4z exhibited potential antitubercular activity against M. tuberculosis H37RV, MIC at 16 μM and 24 μM respectively. The best compound of the series i.e. compound 4y was well tolerated by Swiss-albino mice in acute oral toxicity. Compound 4y possessing a diarylbenzimidazole core, can further be optimized for better activity.
- Chaturvedi, Amit K.,Verma, Amit Kumar,Thakur, Jay Prakash,Roy, Sudeep,Bhushan Tripathi, Shashi,Kumar, Balagani Sathish,Khwaja, Sadiya,Sachan, Naresh K.,Sharma, Ashok,Chanda, Debabrata,Shanker, Karuna,Saikia, Dharmendra,Negi, Arvind S.
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p. 4551 - 4559
(2018/08/11)
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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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- 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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- 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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- 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.
- -
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Paragraph 0060-0062
(2018/06/07)
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- Synthesis, anti-proliferative activity, SAR study, and preliminary in vivo toxicity study of substituted N,N′-bis(arylmethyl)benzimidazolium salts against a panel of non-small cell lung cancer cell lines
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A series of N,N′-bis(arylmethyl)benzimidazolium salts have been synthesized and evaluated for their in vitro anti-cancer activity against select non-small cell lung cancer cell lines to create a structure activity relationship profile. The results indicate that hydrophobic substituents on the salts increase the overall anti-proliferative activity. Our data confirms that naphthylmethyl substituents at the nitrogen atoms (N1(N3)) and highly lipophilic substituents at the carbon atoms (C2and C5(C6)) can generate benzimidazolium salts with anti-proliferative activity that is comparable to that of cisplatin. The National Cancer Institute's Developmental Therapeutics Program tested 1, 3–5, 10, 11, 13–18, 20–25, and 28–30 in their 60 human tumor cell line screen. Results were supportive of data observed in our lab. Compounds with hydrophobic substituents have higher anti-cancer activity than compounds with hydrophilic substituents.
- Shelton, Kerri L.,DeBord, Michael A.,Wagers, Patrick O.,Southerland, Marie R.,Williams, Travis M.,Robishaw, Nikki K.,Shriver, Leah P.,Tessier, Claire A.,Panzner, Matthew J.,Youngs, Wiley J.
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p. 421 - 439
(2016/12/18)
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- SUBSTITUTED BENZIMIDAZOLIUM, PYRIDO-IMIDAZOLIUM, OR PYRAZINO-IMIDAZOLIUM COMPOUNDS AS CHEMOTHERAPEUTICS
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Provided herein are compounds of the formula:(I) wherein: R1, R2, R3, R4, R5, X, A1, A2, A3, and A4 are as defined herein. In some aspects, these compounds may be used to treat cancer and other hyperproliferative disease. In some aspects, compositions, methods of treatment, and methods of synthesis are also provided herein.
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Paragraph 00180
(2017/08/01)
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- A cyclized O-phenylenediamine-based compound of the method for preparing benzimidazole
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The invention belongs to the field of fine chemistry and relates to an improved synthesis method of a benzimidazole compound and a related chemical technology. The synthesis method is characterized by comprising the step of with o-phenylenediamine and 1, 3-dicarbonyl compound as raw materials, synthesizing the benzimidazole compound under the catalysis of protonic acid. The invention mainly provides a novel synthesis method of the benzimidazole compound. The method has the advantages of mild reaction conditions, simple step, easily-obtained raw materials, good functional group compatibility and the like. Benzimidazole is an important biological active group and is widely applied in the field of pharmacy, and therefore, the preparation method has relatively high use value as well as social and economic benefits.
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Paragraph 0032-0034
(2017/01/19)
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- Method for preparing benzimidazole compound through supported bimetallic catalyst at room temperature
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The invention belongs to the technical field of photochemistry organic synthesis, and particularly relates to a method for preparing a benzimidazole compound through a supported bimetallic catalyst at room temperature .The preparation method of the benzimidazole compound comprises the steps that o-phenylenediamine and reactant alcohol are used as initial reactants, a photocatalyst is used as a supported bimetallic nanoparticles, in an organic solvent and under the stirring condition and irradiation of ultraviolet light or visible light or sunlight, the o-phenylenediamine and the reactant alcohol are directly subjected to photocatalysis through light source irradiation to be converted into benzimidazole and a derivative thereof .According to the method, reaction conditions are mild, high-temperature reaction conditions are not needed, the reaction speed at room temperature is high, and the selectivity of the target product benzimidazole is 95% or above .
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Paragraph 0041; 0042; 0043; 0046; 0049; 0053-0060; 0062-0069
(2017/07/21)
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- Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)3 catalyst in the reaction selectivity
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An improved and greener protocol for the synthesis of benzimidazole derivatives, starting from o-phenylenediamine, with different aldehydes is reported. Double-condensation products were selectively obtained when Er(OTf)3 was used as the catalyst in the presence of electron-rich aldehydes. Conversely, the formation of mono-condensation products was the preferred path in absence of this catalyst. One of the major advantages of these reactions was the formation of a single product, avoiding extensive isolation and purification of products, which is frequently associated with these reactions. Theoretical calculations helped to understand the different reactivity established for these reactions. Thus, we found that the charge density on the oxygen of the carbonyl group has a significant impact on the reaction pathway. For instance, electron-rich aldehydes better coordinate to the catalyst, which favours the addition of the amine group to the carbonyl group, therefore facilitating the formation of double-condensation products. Reactions with aliphatic or aromatic aldehydes were possible, without using organic solvents and in a one-pot procedure with short reaction time (2-5 min), affording single products in excellent yields (75-99%). This convenient and eco-friendly methodology offers numerous benefits with respect to other protocols reported for similar compounds.
- Herrera Cano, Natividad,Uranga, Jorge G.,Nardi, Mónica,Procopio, Antonio,Wunderlin, Daniel A.,Santiago, Ana N.
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supporting information
p. 2410 - 2419
(2016/12/07)
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- Catalytic Performance of Hydrophobic Sulfonated Nanocatalysts CMK-5-SO3H and SBA-15-Ph-PrSO3H for Ecofriendly Synthesis of 2-Substituted Benzimidazoles in Water
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The hydrophobicity of environmentally benign organosulfonic acid-functionalized silica (SBA-15-Ph-PrSO3H) and sulfonic acid-based nanoporous carbon (CMK-5-SO3H) was assessed in relation to the green synthesis of 2-substituted benzimidazoles from aldehydes and benzene-1,2-diamine in open air in an aqueous medium. The results are rationalized in terms of the inclusion of the substrates inside hydrophobic cavities of the catalysts. Furthermore, the more hydrophobic and more water-resistant catalyst CMK-5-SO3H showed superior catalytic activity. Their excellent yields, their use of water as a green solvent, and their recyclability and environmentally friendly nature makes these catalysts important alternatives to classical acid catalysts.
- Zareyee, Daryoush,Rostamian Tuyehdarvary, Sakineh,Allahgholipour, Leila,Hossaini, Zinatossadat,Khalilzadeh, Mohammad A.
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p. 1251 - 1254
(2016/05/10)
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- An Efficient Synthesis of 2-Substituted Benzimidazoles via Photocatalytic Condensation of o-Phenylenediamines and Aldehydes
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A photocatalytic method has been developed for the efficient synthesis of functionalized benzimidazoles. This protocol involves photocatalytic condensation of o-phenylenediamines with various aldehydes using the Rose Bengal as photocatalyst. The method was found to be general and was successfully employed for accessing pharmaceutically important benzimidazoles by the condensation of aromatic, heteroaromatic and aliphatic aldehydes with o-phenylenediamines, in good-to-excellent yields. Notably, the method was found to be effective for the condensation of less reactive heterocyclic aldehydes with o-phenylenediamines.
- Kovvuri, Jeshma,Nagaraju, Burri,Kamal, Ahmed,Srivastava, Ajay K.
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supporting information
p. 644 - 650
(2016/10/21)
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- Pd/Al2O3-catalysed redox isomerisation of allyl alcohol: Application in aldol condensation and oxidative heterocyclization reactions
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The application of the Pd/Al2O3 catalyst in allyl alcohol isomerization and subsequent aldol condensation and heterocyclization reactions is described. The activity of Pd/Al2O3 in these transformations is suggested to be due to the participation of the Lewis acidic sites of the support in the activation of the alcohol towards oxidative dehydrogenation by the metal and subsequent hydride transfer. The resulting enol(ate)/aldehyde could undergo further reactions promoted by the acid-base properties of the support. In the aldol condensation reactions of the isomerization product, electron poor aromatic aldehydes and heteroaromatic aldehydes showed the highest activity, while aromatic aldehydes bearing electron donating substituents reacted after transformation to the corresponding N-tosyl imines. 1,2-Disubstituted aromatics gave heterocyclic products in one-pot multistep reaction sequences.
- Zsolnai, Dániel,Mayer, Péter,Szori, Kornél,London, Gábor
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p. 3814 - 3820
(2016/06/13)
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- Cu-Pd/γ-Al2O3 catalyzed the coupling of multi-step reactions: Direct synthesis of benzimidazole derivatives
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The coupling of multi-step reactions catalyzed by a heterogeneous catalyst is an important path to accomplish some unconventional chemical transformations. Since the starting materials generated from previous steps were adsorbed on the catalyst, the activation energy of following steps was largely decreased, and thus the reaction conditions were more mild and environmental friendly. Catalyzed by a multifunctional Cu-Pd/γ-Al2O3 catalyst, the transfer hydrogenation and successive cyclization coupling reaction from o-nitroaniline and alcohol to afford benzimidazole derivatives in high yield was realized. The catalyst could be reused several times without loss of activity. The synergies of reforming hydrogenation of Cu-Pd bimetal and support acidity of γ-Al2O3 were responsible for this catalytic transformation.
- Feng, Feng,Ye, Jia,Cheng, Zheng,Xu, Xiaoliang,Zhang, Qunfeng,Ma, Lei,Lu, Chunshan,Li, Xiaonian
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p. 72750 - 72755
(2016/08/09)
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- Synthesis and evaluation of selected benzimidazole derivatives as potential antimicrobial agents
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A library of 53 benzimidazole derivatives, with substituents at positions 1, 2 and 5, were synthesized and screened against a series of reference strains of bacteria and fungi of medical relevance. The SAR analyses of the most promising results showed that the antimicrobial activity of the compounds depended on the substituents attached to the bicyclic heterocycle. In particular, some compounds displayed antibacterial activity against two methicillin-resistant Staphylococcus aureus (MRSA) strains with minimum inhibitory concentrations (MICs) comparable to the widely-used drug ciprofloxacin. The compounds have some common features; three possess 5-halo substituents; two are derivatives of (S)-2-ethanaminebenzimidazole; and the others are derivatives of one 2-(chloromethyl)-1Hbenzo[ d]imidazole and (1H-benzo[d]imidazol-2-yl)methanethiol. The results from the antifungal screening were also very interesting: 23 compounds exhibited potent fungicidal activity against the selected fungal strains. They displayed equivalent or greater potency in their MIC values than amphotericin B. The 5-halobenzimidazole derivatives could be considered promising broad-spectrum antimicrobial candidates that deserve further study for potential therapeutic applications.
- Alasmary, Fatmah A.S.,Snelling, Anna M.,Zain, Mohammed E.,Alafeefy, Ahmed M.,Awaad, Amani S.,Karodia, Nazira
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supporting information
p. 15206 - 15223
(2015/09/21)
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- AMIDO-SUBSTITUTED AZOLE COMPOUNDS
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The present invention relates to amido-substituted azole compounds of general formula (I), in which X1, X2, R1, R2, R4, R5, R7 and R8 are as defined in the claims which are inhibitors of TNKS1 and/or TNKS2, to methods of preparing said compounds, to intermediate compounds useful for preparing said compounds, to pharmaceutical compositions and combinations comprising said compounds and to the use of said compounds for manufacturing a pharmaceutical composition for the treatment or prophylaxis of a disease, in particular of neoplasms, as a sole agent or in combination with other active ingredients.
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Page/Page column 183
(2015/11/02)
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- Supercritical methanol as solvent and carbon source in the catalytic conversion of 1,2-diaminobenzenes and 2-nitroanilines to benzimidazoles
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Benzimidazoles and N-methylbenzimidazoles were synthesized by simply heating 1,2-diaminobenzenes in supercritical methanol over copper-doped porous metal oxides. These catalysts were derived from synthetic hydrotalcites that only contain earth-abundant starting materials. The carbon equivalents needed for the construction of the benzimidazole core originated from the solvent itself, which is known to undergo reforming to hydrogen and carbon monoxide through the formation of a formaldehyde intermediate. A variety of 1,2-diaminobenzenes were converted to the corresponding mixtures of benzimidazoles and N-methylated analogues in good yields. Interestingly, the more challenging, but readily available 2-nitroanilines, which require an additional reduction step prior to cyclization, could also be successfully converted to benzimidazoles in high selectivity. Furthermore, various other alcohols were applied besides methanol, to obtain 2-alkyl- and 1,2-dialkylbenzimidazoles. Preliminary mechanistic insights into the origins of N-alkylation as well as the reactivity of the nitro derivatives are discussed.
- Sun, Zhuohua,Bottari, Giovanni,Barta, Katalin
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p. 5172 - 5181
(2015/12/08)
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- Expedient synthesis of benzimidazoles using amides
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In the present report an efficient, rapid, facile and inexpensive route for the synthesis of benzimidazoles using 1,2-arylenediamines and N,N-dimethylformamide in acidic medium under thermal/microwave condition is developed. This reaction was further explored with the different amides to afford a library of 2-substituted benzimidazoles. The advantage of the present synthetic method includes shorter reaction time, easy work up and excellent yields without using catalysts.
- Kattimani, Pramod P.,Kamble, Ravindra R.,Meti, Gangadhar Y.
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p. 29447 - 29455
(2015/04/14)
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- Gadolinium (III) chloride catalyzed facile synthesis of 2-substituted benzimidazoles under solvent-free conditions
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A series of 2-substituted benzimidazoles have been prepared from o-diamines and 1,3-dicarbonyl compounds using Gadolinium chloride as a catalyst under solvent free condition in good yields. Gadolinium chloride has been demonstrated as a mild and efficient catalyst.
- Sathaiah,Venkat Lingaiah,Chandra Shekhar,Ravi Kumar,Raju,Shanthan Rao
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p. 953 - 957
(2015/08/19)
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- Convenient synthesis of benzothiazoles and benzimidazoles through bronsted acid catalyzed cyclization of 2-amino thiophenols/anilines with β-diketones
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Bronsted acid catalyzed cyclization reactions of 2-amino thiophenols/anilines with β-diketones under oxidant-, metal-, and radiation-free conditions are described. Various 2-substituted benzothiazoles/benzimidazoles are obtained in satisfactory to excellent yields. Different groups such as methyl, chloro, nitro, and methoxy linked on benzene rings were tolerated under the optimized reaction conditions.
- Mayo, Muhammad Shareef,Yu, Xiaoqiang,Zhou, Xiaoyu,Feng, Xiujuan,Yamamoto, Yoshinori,Bao, Ming
-
supporting information
p. 764 - 767
(2014/03/21)
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- Green synthesis of benzimidazole derivatives catalyzed by ionic liquid under microwave irradiation
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An efficient synthesis of benzimidazole derivatives from o-phenylene diamine and substituted aromatic aldehyde catalyzed by ionic liquid under microwave irradiation was reported. The synthesis conditions were first optimized by single factor experiments. Then, a central composite design combined with response surface methodology was used to study the most effective factors. Optimal conditions were synthesis time 1 h, the reactant/catalyst molar ratio 1:1:0.200, the temperature 50 °C and the microwave power 500 W. Under optimized conditions, the yields of benzimidazole derivatives were 78.55-97.66 %. This method offered the outstanding advantages, such as faster reaction rate, higher yields, recyclable catalyst, environmental friendliness, and simple workup procedure.
- Qin, Mingcong,Fu, Yujie,Wang, Xiqing,Zhang, Yuhang,Ma, Weidong
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p. 1553 - 1559
(2015/02/05)
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- Microwave-assisted, tetrabutylammonium hydroxide catalysed 1,4-addition of water to α,β-unsaturated ketones and α,β-ynones in aqueous solution
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Microwave-assisted, tetrabutylammonium hydroxide catalysed 1,4-addition reactions of water to α,β-unsaturated ketones and α,β-ynones take place efficiently in water. Reactions of the resulting β-hydroxy ketones lead to the formation of either C-C bond cleavage or annulation products. This journal is
- Lee, Hyejeong,Jun, Chul-Ho
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p. 48331 - 48335
(2014/12/11)
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- Synthesis of 2,5-disubstitued benzimidazole using SnCl2- catalyzed reduction system at room temperature
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Stannous chloride dihydrate is used as an efficient catalyst in reductive cyclization of 2-nitro-5-substituted aniline Schiff base leading to stable 2,5-disubstitued benzimidazole derivatives in excellent yields with good purity. It provides a novel method of synthesis of 2,5-disubstitued benzimidazole under reductive system at room temperature.
- Duan, Li-Ping,Li, Qiang,Wu, Ning-Bo,Xu, Dong-Fang,Zhang, Hao-Bing
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p. 155 - 158
(2014/02/14)
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- Metal-free aerobic oxidative C-N bond cleavage of tertiary amines for the synthesis of N-heterocycles with high atom efficiency
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An efficient metal-free aerobic oxidative C-N bond cleavage of tertiary amines has been developed to construct N-heterocycles using molecular oxygen as the sole oxidant with high atom efficiency, in which all of the three alkyl groups in tertiary amines can be utilized and transformed into N-heterocycles. This journal is the Partner Organisations 2014.
- Chen, Xiuling,Chen, Tieqiao,Zhou, Yongbo,Han, Daoqing,Han, Li-Biao,Yin, Shuang-Feng
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supporting information
p. 3802 - 3807
(2014/06/09)
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- Novel strategy for synthesis of substituted benzimidazo[1,2-a]quinolines
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An efficient method for the synthesis of benzimidazo[1,2-a]quinolines under transition-metal-free conditions has been developed through a cascade reaction involving sequential aromatic nucleophilic substitution and intramolecular Knoevenagel condensation reactions. This method is applicable for the synthesis of a wide range of benzimidazo[1,2-a]quinoline derivatives from readily available 2-fluoroarylaldehyde and benzimidazole substrates.
- Kato, Jun-Ya,Ito, Yutaro,Ijuin, Ryosuke,Aoyama, Hiroshi,Yokomatsu, Tsutomu
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supporting information
p. 3794 - 3797
(2013/08/23)
-
- New antibacterial diazotized derivatives of 5-amino azaheterocycles
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Six new diazotized derivatives of pharmacologically important azaheterocycles (2a-d, 4a-b) were prepared from their corresponding 5-amino benzimidazoles (1a-d) and benzimidazolones (3a-b). All new compounds have been characterized on the basis of their IR, NMR and Mass spectral data. Antibacterial activity of these compounds is also been reported.
- Gondal, Humaira Yasmeen,Ali, Muhammad
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p. 1343 - 1348
(2014/01/06)
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- Reusable α-MoO3 nanobelts catalyzes the green and heterogeneous condensation of 1,2-diamines with carbonyl compounds
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Crystalline nanobelts of α-MoO3 have been obtained successfully using novel and safe agents through a simple and safe sol-gel method (polymerizing-complexing) and characterized by XRD, FT-IR, Raman spectroscopies, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and the temperature programmed desorption (TPD) of ammonia. An orthorhombic lattice system for nano-MoO3 was established. The HRTEM images showed that the nanobelt morphology of α-MoO3 mostly ranged from 20-70 nm in width and 200-400 nm in length. The ammonia TPD profile demonstrated strong acidic sites. The spectral and analysis data confirmed the effectiveness of the method for the preparation of α-MoO3 nanobelts by prevention of grain growth or agglomeration of the particles. The nanostructured MoO3 exhibited a high efficiency in catalyzing the condensation reaction of various 1,2-diamine and carbonyl compounds for synthesis of heterocyclic compounds. The recovery of the title heterogenous nanocatalyst was easy and efficient and its catalytic activity was strikingly different from the bulk material.
- Jafarpour, Maasoumeh,Rezaeifard, Abdolreza,Ghahramaninezhad, Mahboube,Tabibi, Tooba
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p. 2087 - 2095
(2013/10/08)
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- CuO nano-particles supported on silica, a new catalyst for facile synthesis of benzimidazoles, benzothiazoles and benzoxazoles
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A facile synthetic route for benzimidazoles, benzothiazoles and benzoxazoles comprising the reaction of corresponding o-phenylenediamine, o-aminothiophenol and o-aminophenol with various aldehydes using silica supported nano-copper (II) oxide as a catalyst has been described. The catalyst exhibited clean reaction profile with excellent yields in a short reaction time. The catalyst can be recycled effectively after use.
- Inamdar, Suleman M.,More, Vinod K.,Mandal, Sisir K.
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p. 579 - 583
(2013/02/23)
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- Cobalt- and iron-catalyzed redox condensation of o-substituted nitrobenzenes with alkylamines: A step- and redox-economical synthesis of diazaheterocycles
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A wide variety of functionalized 2-aryl benzimidazoles can be prepared by a solvent-free cobalt- or iron-catalyzed redox condensation of 2-nitroanilines and benzylamines. The cascade including benzylamine oxidation, nitro reduction, condensation, and aromatization occurs without any added reducing or oxidizing agent. The method can be extended to other alkylamines as reducing components or 2-nitrobenzamides as oxidizing components when using an iron/sulfur catalyst to afford various diazaheterocycles.
- Nguyen, Thanh Binh,Bescont, Julie Le,Ermolenko, Ludmila,Al-Mourabit, Ali
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supporting information
p. 6218 - 6221
(2014/01/17)
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- Palladium-catalysed dehydrogenative generation of imines from amines. A nature-inspired route to indoles via cross-couplings of amines with arylhydrazines
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H-substituted imines are elusive compounds formed when aldehydes or ketones are mixed with ammonia. However, this class of molecules can be prepared through selective removal of a hydrogen molecule from a primary amine using a transition metal catalyst. This biomimetic transformation, previously employed for the N-alkylation of anilines, is applied here to a domino preparation of differently substituted indoles from aliphatic primary amines and arylhydrazines. Several different linear and branched aliphatic primary amines are oxidized with reusable palladium on charcoal to the corresponding primary imines entrapped as arylhydrazones that can be isolated as such. Arylhydrazones can be further converted into N-alkylindole derivatives via an acid-mediated indolisation reaction. The one-pot domino hydrogen transfer Fischer indole synthesis under heterogeneous catalysis is also possible, giving access to diverse substituted indoles, including NH indoles obtained after deprotection of the corresponding benzyl compounds. The truly heterogeneous nature of the catalyst was demonstrated by recycling the catalyst in the same reaction, and in other palladium-catalysed transformations.
- Taddei, Maurizio,Mura, Manuel G.,Rajam?ki, Suvi,De Luca, Lidia,Porcheddu, Andrea
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p. 3002 - 3013
(2014/03/21)
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- A green and efficient protocol for the synthesis of quinoxaline, benzoxazole and benzimidazole derivatives using heteropolyanion-based ionic liquids: As a recyclable solid catalyst
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In this paper, we introduce two nonconventional ionic liquid compounds which are composed of propane sulfonate functionalized organic cations and heteropolyanions as green solid acid catalysts for the highly efficient and green synthesis of 2,3-disubstitutedquinoxaline derivatives. These ionic liquids are in the solid state at room temperature and the synthesis is carried out via the one-pot condensation reaction of various o-phenylenediamine with 1,2-diketone derivatives. Benzoxazole and benzimidazole derivatives were also synthesized by these novel catalysts via the one-pot condensation from reaction orthoester with o-aminophenol (synthesis of benzoxazole derivatives) and ophenylenediamine (synthesis of benzimidazole derivatives). All experiments successfully resulted in the desired products. The described novel synthesis method has several advantages of safety, mild condition, high yields, short reaction times, simplicity and easy workup compared to the traditional method of synthesis.
- Vahdat, Seyed Mohammad,Baghery, Saeed
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p. 618 - 627
(2013/09/12)
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