- Rhodium(I) N-Heterocyclic Carbene Bioorganometallics as in Vitro Antiproliferative Agents with Distinct Effects on Cellular Signaling
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Organometallics with N-heterocyclic carbene (NHC) ligands have triggered major interest in inorganic medicinal chemistry. Complexes of the type Rh(I)(NHC)(COD)X (where X is Cl or I, COD is cyclooctadiene, and NHC is a dimethylbenzimidazolylidene) represent a promising type of new metallodrugs that have been explored by advanced biomedical methods only recently. In this work, we have synthesized and characterized several complexes of this type. As observed by mass spectrometry, these complexes remained stable over at least 3 h in aqueous solution, after which hydrolysis of the halido ligands occurred and release of the NHC ligand was evident. Effects against mitochondria and general cell tumor metabolism were noted at higher concentrations, whereas phosphorylation of HSP27, p38, ERK1/2, FAK, and p70S6K was induced substantially already at lower exposure levels. Regarding the antiproliferative activity in tumor cells, a clear preference for iodido over chlorido secondary ligands was noted, as well as effects of the substituents of the NHC ligand.
- Oehninger, Luciano,Spreckelmeyer, Sarah,Holenya, Pavlo,Meier, Samuel M.,Can, Suzan,Alborzinia, Hamed,Schur, Julia,Keppler, Bernhard K.,W?lfl, Stefan,Ott, Ingo
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- Methanol as the C1source: Redox coupling of nitrobenzenes and alcohols for the synthesis of benzimidazoles
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We present an operationally simple redox coupling for the synthesis of N-1 substituted benzimidazoles using feedstock building block 2-nitroaniline derivatives as the precursors and methanol as the C1 source. Higher atom, step, and redox economies and exc
- An, Jie,Lai, Zemin,Li, Hengzhao,Peng, Mengqi,Sun, Yanhao,Yan, Zihan,Yang, Ruoyan,Zhang, Yuntong
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supporting information
p. 748 - 753
(2022/02/02)
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- One-Pot Transformation of Lignin and Lignin Model Compounds into Benzimidazoles
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It is a challenging task to simultaneously achieve selective depolymerization and valorization of lignin due to their complex structure and relatively stable bonds. We herein report an efficient depolymerization strategy that employs 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively convert different oxidized lignin models to a wide variety of 2-phenylbenzimidazole-based compounds in up to 94 % yields, by reacting with o-phenylenediamines with varied substituents. This method could take full advantage of both Cβ and/or Cγ atom in lignin structure to furnish the desirable products instead of forming byproducts, thus exhibiting high atom economy. Furthermore, this strategy can effectively transform both the oxidized hardwood (birch) and softwood (pine) lignin into the corresponding degradation products in up to 45 wt% and 30 wt%, respectively. Through a “one-pot” process, we have successfully realized the oxidation/depolymerization/valorization of natural birch lignin at the same time and produced the benzimidazole derivatives in up to 67 wt% total yields.
- Guo, Tao,He, Jianghua,Liu, Tianwei,Zhang, Yuetao
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supporting information
(2022/02/07)
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- Sustainable Synthesis of 2-Hydroxymethylbenzimidazoles using D-Fructose as a C2 Synthon
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D-fructose, a biomass-derived carbohydrate has been identified as an environmentally benign C2 synthon in the preparation of synthetically useful 2-hydroxymethylbenzimidazole derivatives by coupling with 1,2-phenylenediamines. Proof of concept was established by synthesizing 23 examples using BF3.OEt2 (20 mol%), TBHP (5.5 M, decane) (1.0 equiv.) in CH3CN at 90 °C for 1 h. The pivotal features of this method include metal-free conditions, short time, good functional group tolerance, gram scale feasibility and the synthesis of benzimidazole fused 1,4-oxazine. Control studies with conventional C2 synthons did not produce the desired product, thus suggesting a new reaction pathway from D-fructose.
- Raja, Dineshkumar,Philips, Abigail,Sundaramurthy, Devikala,Chandru Senadi, Gopal
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supporting information
p. 3754 - 3759
(2021/10/14)
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- Method for synthesizing benzimidazole from carbon dioxide and o-phenylenediamine compound
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The invention discloses a method for synthesizing benzimidazole from carbon dioxide and an o-phenylenediamine compound, the method is characterized in that an amino-containing functionalized ordered mesoporous polymer is used as a catalyst, o-phenylenediamine and carbon dioxide are used as raw materials, dimethylaminoborane is used as a hydrogen reduction reagent, carbon dioxide and the o-phenylenediamine compound are catalyzed to react in an NMP solvent to generate a benzimidazole compound, wherein the dosage of a catalyst is 0.01-1mol% based on the nitrogen content of the o-phenylenediamine compound; the filling pressure of the carbon dioxide is 0.1-2MPa; the reaction temperature is 60-180DEG C; the molar ratio of the catalyst to the NMP is 1:50-100. Compared with the prior art, the catalyst has the advantages of simple preparation, high catalytic activity, capability of catalyzing the reaction of carbon dioxide and the o-phenylenediamine compound under mild conditions to generate benzimidazole and derivatives thereof, and the like.
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Paragraph 0029-0032
(2021/06/06)
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- A substituent- And temperature-controllable NHC-derived zwitterionic catalyst enables CO2upgrading for high-efficiency construction of formamides and benzimidazoles
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Chemocatalytic upgrading of the greenhouse gas CO2 to valuable chemicals and biofuels has attracted broad attention in recent years. Among the reported approaches, N-formylation of CO2 with an amine is of great significance due to its versatility in the construction of N-containing linear and cyclic skeletons. Herein, a stable N-heterocyclic carbene-carboxyl adduct (NHC-CO2) was facilely prepared and could be used as a recyclable zwitterionic catalyst for efficient CO2 reductive upgrading via either N-formylation or further coupling with cyclization under mild conditions (25 °C, 1 atm CO2) using hydrosilane as a hydrogen source. More than 30 different alkyl and aromatic amines could be transformed into the corresponding formamides or benzimidazoles with remarkable yields (74%-98%). The electronic effect of the introduced substituent on NHC-CO2 was found to evidently affect the thermostability and nucleophilicity of the zwitterionic catalyst, which is directly correlated with its catalytic activity. Moreover, NHC-CO2 could supply CO2 by in situ decarboxylation at a specific temperature that is dependent on the introduced substituent type. Experimental and computational studies showed that the carboxyl species on NHC-CO2 was not only a nucleophilic center, but also a C1 source which rapidly captures or substitutes ambient CO2 during hydrosilylation. In addition, a simple and green conceptual process was designed for the product purification and catalyst recycling, with a good feasibility for small-scale production.
- Li, Hu,Li, Zhengyi,Wu, Hongguo,Yang, Song,Yu, Zhaozhuo,Zhang, Lilong,Zhu, Kaixun
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supporting information
p. 5759 - 5765
(2021/08/23)
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- Reductive cyclization of o-phenylenediamine with CO2 and BH3NH3 to synthesize 1H-benzoimidazole derivatives
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A simple and green protocol was developed for the reductive cyclization of o-phenylenediamine with CO2 and BH3NH3 to yield 1H-benzimidazole. The desired 1H-benzimidazole derivatives were produced under mild conditions. Mechanism investigation indicated that the coordination of o-phenylenediamine with the boron atom of BH3NH3 promoted the transfer of the formyl group to form a stable intermediate, which facilitated the intramolecular nucleophilic addition-elimination for the formation of target product. In this process, BH3NH3 served multifunctional roles, acting as a reducing agent and a formylation catalyst.
- Han, Limin,Hong, Hailong,Li, Xiao,Yang, Yue,Zhang, Junhua,Zhu, Ning
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supporting information
(2021/09/28)
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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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- Transition-metal and oxidant-free approach for the synthesis of diverse N-heterocycles by TMSCl activation of isocyanides
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A highly efficient TMSCl-mediated addition of N-nucleophiles to isocyanides has been achieved. This transition-metal and oxidant-free strategy has been applied to the construction of various N-heterocyles such as quinazolinone, benzimidazole and benzothiazole derivatives by the use of distinct amino-based binucleophiles. The notable feature of this protocol includes its mild reaction condition, broad functional group tolerance and excellent yield. This journal is
- Chen, Fen-Er,Dong, Lin,Li, Hongyan,Liu, Jinxin,Luo, Liangliang,Xiao, You-Cai,Zhou, Yuan
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p. 29257 - 29262
(2020/10/02)
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- Facile access to: N-formyl imide as an N-formylating agent for the direct synthesis of N-formamides, benzimidazoles and quinazolinones
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N-Formamide synthesis using N-formyl imide with primary and secondary amines with catalytic amounts of p-toluenesulfonic acid monohydrate (TsOH·H2O) is described. This reaction is performed in water without the use of surfactants. Moreover, N-formyl imide is efficiently synthesized using acylamidines with TsOH·H2O in water. In addition, N-formyl imide was successfully used as a carbonyl source in the synthesis of benzimidazole and quinazolinone derivatives. Notable features of N-formylation of amines by using N-formyl imide include operational simplicity, oxidant- A nd metal-free conditions, structurally diverse products, and easy applicability to gram-scale operation.
- Huang, Hsin-Yi,Liang, Chien-Fu,Lin, Xiu-Yi,Yen, Shih-Yao
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supporting information
p. 5726 - 5733
(2020/08/21)
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- K2S as Sulfur Source and DMSO as Carbon Source for the Synthesis of 2-Unsubstituted Benzothiazoles
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We describe a three-component reaction of o-iodoanilines with K2S and DMSO that provides 2-unsubstituted benzothiazoles in moderate to good isolated yields with good functional group tolerance. Electron-rich aromatic amines and o-phenylenediamines instead of o-iodoanilines provided 2-unsubstituted benzothiazoles and 2-unsubstituted benzimidazoles with and without K2S under similar conditions. Notably, DMSO plays three vital roles: carbon source, solvent, and oxidant.
- Deng, Guobo,Kuang, Daizhi,Liang, Yun,Yang, Yuan,Yu, Jiangxi,Zhang, Fuxing,Zhu, Xiaoming
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supporting information
p. 3789 - 3793
(2020/06/04)
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- Synthesis method of ammonium acetate mediated benzimidazole compound
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The invention discloses a synthesis method of a benzimidazole compound mediated by ammonium acetate. The synthesis method comprises the following steps: adding an o-phenylenediamine compound, dimethylsulfoxide, an additive 1 and an additive 2 into a reaction tube, carrying out a stirring reaction at 130-150 DEG C, cooling the reaction product to room temperature after the reaction is finished, and carrying out separation and purification on the product to obtain the benzimidazole compound. The invention develops a method for synthesizing a benzimidazole compound under the mediation of ammonium acetate by taking DMSO as a carbon source and an oxidant and an o-phenylenediamine compound as a substrate under the condition of no metal catalyst. The synthesis method does not need a metal catalyst, and the required carbon source and oxidant have the characteristics of low toxicity, low price, easiness in obtaining, stable performance and the like. The method has the advantages of easiness inoperation, few steps, mild reaction conditions, better functional group tolerance and the like, and provides a new valuable way for synthesizing benzimidazole compounds.
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Paragraph 0042-0044
(2020/11/23)
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- Endogenous X-C=O species enable catalyst-free formylation prerequisite for CO2reductive upgrading
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CO2, the main component of greenhouse gas, is currently developed as a promising surrogate of carbon feedstock. Among various conversion routes, CO2undergoing catalytic reduction can furnish hydrogen/energy carriers and value-added chemicals, while specific metal-containing catalysts or organocatalysts are often prerequisite for smooth proceeding of the involved reaction processes. In this work, both formic acid and N-containing benzoheterocyclic compounds (including various benzimidazoles, benzothiazole, and benzoxazole) along with silanols could be synthesized with high yields (>90%) from catalyst-free reductive upgrading of CO2under mild conditions (50 °C). The endogenous X-CO species, derived from the N-methyl-substituted amide-based solvent [Me2N-C(O)-R], especially PolarClean, and O-formyl group [O-C(O)-H] of in situ formed silyl formate, were found to play a prominent promotional role in the activation of the used hydrosilane for reductive CO2insertion, as demonstrated by density functional theory (DFT) calculations and isotopic labeling experiments. Moreover, reaction mechanisms and condition-based sensitivity assessment were also delineated.
- Dai, Wenshuai,Li, Hu,Saravanamurugan, Shunmugavel,Wu, Hongguo,Yang, Song
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p. 5822 - 5832
(2020/10/21)
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- Metal-Free Synthesis of Benzimidazoles via Oxidative Cyclization of d -Glucose with o-Phenylenediamines in Water
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d-Glucose has been identified as an efficient C1 synthon in the synthesis of benzimidazoles from o-phenylenediamines via an oxidative cyclization strategy. Isotopic studies with 13C6-d-glucose and D2O unambiguously confirmed the source of methine. The notable features of this method include the following: broad functional group tolerance, a biorenewable methine source, excellent reaction yields, a short reaction time, water as an environmentally benign solvent, and the synthesis of vitamin B12 component on the gram scale.
- Raja, Dineshkumar,Philips, Abigail,Palani, Pushbaraj,Lin, Wei-Yu,Devikala, Sundaramurthy,Senadi, Gopal Chandru
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p. 11531 - 11540
(2020/10/12)
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- Visible-light-induced aerobic oxidative desulfurization of 2-mercaptobenzimidazolesviaa sulfinyl radical
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A mild transition-metal-free non-toxic aerobic photoredox system was found to enable highly efficient desulfurization of 2-mercaptobenzimidazoles. This viable catalytic system includes Rose Bengal in a low catalyst loading as a photosensitizer and cheap, non-toxic NaCl in a catalytic amount as an additive, combined with an oxygen atmosphere. This protocol provides an important alternative access to a broad range of benzimidazole and deuterated benzimidazole products in generally high yields with good tolerance of various synthetically and pharmaceutically useful functionalities. The mechanistic studies reveal that both single electron transfer and energy transfer probably occur in the initial step and a sulfinyl radical intermediate is involved in the key desulfurization process.
- Deng, Guo-Jun,Fu, Mei,Huang, Huawen,Ji, Xiaochen,Li, Yongtong
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supporting information
p. 5594 - 5598
(2020/09/21)
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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 0072
(2019/03/28)
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- Cobalt-catalyzed synthesis of N-containing heterocycles: Via cyclization of ortho -substituted anilines with CO2/H2
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The CO2-involved synthesis of chemicals is of great significance from the green and sustainable chemistry viewpoint. Herein, we report a non-noble metal catalytic system composed of CoF2, CsF and P(CH2CH2PPh2)3 (denoted as PP3) for the synthesis of N-containing heterocycles from ortho-substituted anilines and CO2/H2. Mechanism investigation indicates that [Co(PP3)H(CO2)]+ is a catalytically active intermediate under working conditions; and CsF plays important roles in activating ortho-substituted anilines via hydrogen bond interactions, thus promoting the formation of the final products. This catalytic system is highly efficient, and allows a wide scope of ortho-substituted anilines, together with excellent functional group tolerance, affording various N-containing heterocycles in good to excellent yields.
- Ke, Zhengang,Yu, Bo,Wang, Huan,Xiang, Junfeng,Han, Juanjuan,Wu, Yunyan,Liu, Zhenghui,Yang, Peng,Liu, Zhimin
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supporting information
p. 1695 - 1701
(2019/04/10)
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- In Situ Formation of Frustrated Lewis Pairs in a Water-Tolerant Metal-Organic Framework for the Transformation of CO2
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Frustrated Lewis pairs (FLPs) consist of sterically hindered Lewis acids and Lewis bases, which provide high catalytic activity towards non-metal-mediated activation of “inert” small molecules, including CO2 among others. One critical issue of homogeneous FLPs, however, is their instability upon recycling, leading to catalytic deactivation. Herein, we provide a solution to this issue by incorporating a bulky Lewis acid-functionalized ligand into a water-tolerant metal-organic framework (MOF), named SION-105, and employing Lewis basic diamine substrates for the in situ formation of FLPs within the MOF. Using CO2 as a C1-feedstock, this combination allows for the efficient transformation of a variety of diamine substrates into benzimidazoles. SION-105 can be easily recycled by washing with MeOH and reused multiple times without losing its identity and catalytic activity, highlighting the advantage of the MOF approach in FLP chemistry.
- Shyshkanov, Serhii,Nguyen, Tu N.,Ebrahim, Fatmah Mish,Stylianou, Kyriakos C.,Dyson, Paul J.
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supporting information
p. 5371 - 5375
(2019/03/17)
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- Sustainable methine sources for the synthesis of heterocycles under metal- and peroxide-free conditions
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Alcohols and ethers were identified as sustainable methine sources for synthesizing quinazolinone and benzimidazole derivatives using a combination of TsOH·H2O/O2 and appropriate bis-nucleophiles for the first time. Deuterium labeling studies clearly proved that the C2 hydrogen of the synthesized heterocycles came from the methine source. These unique reaction conditions were successfully applied to the synthesis of echinozolinone (2e′), 2f′ (a common precursor of rutaecarpine and (±) evodiamine), and dimedazole (6d). Notable features of this method include its low toxicity, use of commercial feedstocks as substrates, low cost, broad functional group tolerance and suitability for a wide range of bis-nucleophilic starting materials.
- Senadi, Gopal Chandru,Kudale, Vishal Suresh,Wang, Jeh-Jeng
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supporting information
p. 979 - 985
(2019/03/12)
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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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supporting information
p. 67 - 72
(2018/12/05)
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- Catalytic synthesis of benzimidazoles and organic carbamates using a polymer supported zinc catalyst through CO2 fixation
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Utilization of carbon dioxide in chemical fixation for synthesis of fine chemicals like benzimidazoles, organic carbamates, etc. is in high demand in recent years as carbon dioxide is a cost effective, sustainable, and green renewable C1 source. In this article we present the design and synthesis of an organically modified polystyrene bound heterogeneous [PS-Zn(ii)-SALTETA] catalyst. The catalyst has been characterized thoroughly by Fourier transform infrared spectroscopy, atomic absorption spectroscopy, thermo gravimetric analysis, PXRD, SEM and EDAX studies. The catalyst was used for cyclization of o-phenylenediamines through insertion of carbon dioxide in order to produce benzimidazoles in the presence of dimethylamine borane (DMAB). The developed catalytic procedure is sustainable, economical and efficient owing to the utilization of ethanol/water as a biodegradable and environment friendly solvent system. Besides benzimidazole production the catalyst was also very active for manufacture of organic carbamates from anilines and n-butyl bromide under atmospheric CO2 pressure under solvent free conditions at room temperature and the catalytic protocol showed outstanding functional group tolerance. Moreover the catalyst is highly recyclable and reusable.
- Biswas, Imdadul Haque,Biswas, Surajit,Islam, Md Sarikul,Riyajuddin, Sk,Sarkar, Priyanka,Ghosh, Kaushik,Islam, Sk Manirul
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p. 14643 - 14652
(2019/09/30)
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- Cu@U-g-C3N4 Catalyzed Cyclization of o-Phenylenediamines for the Synthesis of Benzimidazoles by Using CO2 and Dimethylamine Borane as a Hydrogen Source
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Abstract: This work reports a green and sustainable route for the synthesis of benzimidazoles via C–N bond formation using carbon dioxide (CO2) as a C1 carbon source. In this work, Cu@U-g-C3N4 catalyst was prepared from urea derived porous graphitic carbon?nitride (U-g-C3N4) and CuCl2 and characterized by FT-IR, XRD, XPS, SEM, TPD etc. The Cu@U-g-C3N4 as a heterogeneous recyclable catalyst has been employed first time for the cyclization of o-phenylenediamines (OPD) with CO2 to benzimidazoles using dimethylamine borane (DMAB). The proposed protocol becomes sustainable and efficient due to the use of propylene carbonate/water as a suitable biodegradable, economical and environmentally benign solvent system. The proposed catalytic system showed a wide range of substrate scope for the synthesis of benzimidazoles in good to excellent yields. Graphical Abstract: [Figure not available: see fulltext.]
- Phatake, Vishal V.,Bhanage, Bhalchandra M.
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p. 347 - 359
(2018/11/23)
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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 0040; 0042; 0050; 0051
(2019/02/10)
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- Novel pyrrolo-imidazole derivatives and preparation method and application thereof
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The invention discloses novel pyrrolo-imidazole derivatives and a preparation method and application thereof, and relates to the field of organic synthesis and medical chemistry. The derivatives referto benzimidazo-pyrrole compounds and medicinal salts, enantiomers, diastereoisomers or racemes; a synthetic method of the novel pyrrolo-imidazole derivatives is simple and high in yield; the derivatives are of good antibacterial activity against various fungi and have a promising application prospect in antibacterial anti-cancer activity application.
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Paragraph 0041; 0042; 0044-0051
(2018/09/12)
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- Ru@PsIL-Catalyzed Synthesis of N-Formamides and Benzimidazole by using Carbon Dioxide and Dimethylamine Borane
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This work reports the synthesis and characterization of ruthenium nanoparticles (Ru NPs) supported on polymeric ionic liquids (PILs). This catalyst shows high catalytic activity towards the N-formylation of amines and synthesis of benzimidazoles from 1,2-diamines and carbon dioxide (CO2) by reductive dehydrogenation of dimethylamine borane. This methodology shows excellent functional group tolerance with broad substrate scope towards the synthesis of N-formamides and benzimidazoles. Interestingly, this protocol also provides the tandem reduction of 2-nitroamines and CO2 to synthesize benzimidazoles. It was proposed that the ionic liquid phase of the polymer plays pivotal roles such as assisting the stabilization of nanoparticles electrostatically, providing an ionic environment, and controlling the easy access of the substrates/reagents to the active sites. The developed methodology utilizes CO2 as a C1 source and water/ethanol as a green solvent system. Additionally, the catalyst was found to be recyclable in nature and shows five consecutive recycling runs without significant loss in its activity.
- Saptal, Vitthal B.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
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p. 2593 - 2600
(2018/04/30)
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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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- 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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- Nano-Ni(II)/Y Zeolite Catalyzed Synthesis of 2-Aryl- and 2-Alkyl Benzimidazoles Under Solvent-Free Conditions
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Synthesis of some benzimidazole derivatives via condensation reaction of o-phenylenediamine derivatives with aromatic aldehydes or orthoesters under solvent-free conditions over nano-Ni(II)/Y zeolite as a heterogeneous catalyst is reported. Some advantages of this green method are easy purification, environmentally friendly conditions, low catalyst loadings, and nontoxic nature.
- Mobinikhaledi,Zendehdel,Goudarzi,Bardajee, G. Rezanejade
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p. 1526 - 1531
(2016/06/09)
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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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- Atmospheric CO2 promoted synthesis of N-containing heterocycles over B(C6F5)3 catalyst
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B(C6F5)3 combined with atmospheric CO2 was found to be highly effective for the cyclization of ortho-substituted aniline derivatives with N,N-dimethylformamide (DMF), and a series of N-containing heterocycles including benzothiazoles, benzimidazoles, quinazolinone and benzoxazole were obtained in good to excellent yields.
- Gao, Xiang,Yu, Bo,Mei, Qingqing,Yang, Zhenzhen,Zhao, Yanfei,Zhang, Hongye,Hao, Leiduan,Liu, Zhimin
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p. 8282 - 8287
(2016/10/11)
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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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- N-Substituted Formamides as C1-Sources for the Synthesis of Benzimidazole and Benzothiazole Derivatives by Using Zinc Catalysts
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An efficient and convenient one-pot protocol has been developed for the synthesis of a variety of benzimidazole, benzoxazole, and benzothiazole derivatives. This novel approach uses various o-phenylenediamines and N-substituted formamides (C1 sources) in a zinc-catalyzed cyclization in the presence of poly(methylhydrosiloxane) to afford the corresponding derivatives as sole products in moderate to excellent yields.
- Nale, Deepak B.,Bhanage, Bhalchandra M.
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p. 2835 - 2842
(2015/12/18)
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- Ionic Liquid-Catalyzed C-S Bond Construction using CO2 as a C1 Building Block under Mild Conditions: A Metal-Free Route to Synthesis of Benzothiazoles
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The construction of the C-S bond using CO2 as a C1 feedstock can be considered as a green route for the synthesis of S-containing compounds and is of great significance. Herein, we report the acetate-based ionic liquids (ILs)-catalyzed synthesis of benzothiazoles via cyclization of 2-aminothiophenols with CO2 and hydrosilane under mild conditions (e.g., 60 °C, 0.5 MPa). It was found that the IL (e.g., 1-butyl-3-methylimidazolium acetate, [Bmim][OAc]) served as a multifunctional catalyst with activating CO2 and hydrosilane to form a formoxysilane intermediate, as well as simultaneously activating 2-aminothiophenols through a hydrogen bond, finally resulting in the production of benzothiazoles. [Bmim][OAc] showed the best performance, and a series of benzothiazoles were obtained in high yields. To the best of our knowledge, this is the first protocol for the synthesis of benzothiazoles using CO2 as a C1 building block under metal-free and mild conditions.
- Gao, Xiang,Yu, Bo,Yang, Zhenzhen,Zhao, Yanfei,Zhang, Hongye,Hao, Leiduan,Han, Buxing,Liu, Zhimin
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p. 6648 - 6652
(2015/11/23)
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- A novel ionic liquid based on imidazolium cation as an efficient and reusable catalyst for the one-pot synthesis of benzoxazoles, benzthiazoles, benzimidazoles and 2-arylsubstituted benzimidazoles
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A novel dicationic ionic liquid based on imidazolium cation is designed, synthesized and successfully used as catalyst for the one-pot synthesis of benzoxazoles, benzthiazoles, benzimidazoles and 2-arylsubstituted benzimidazoles. The remarkable feature of this new catalyst is its ethyleneoxy bridge which participates in dissolving organic compound in ionic liquid. The application of this ionic liquid is studied in a new one-pot method for synthesis of heterocyclic compounds under solvent-free conditions. Simple and convenient procedure, high conversion, reusability of catalyst, easy purification and shorter reaction time are the advantageous features of this method.
- Hasanpour, Maede,Eshghi, Hossein,Bakavoli, Mehdi,Mirzaeia, Mahdi
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p. 412 - 419
(2015/05/27)
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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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- Gold-Catalyzed Reductive Transformation of Nitro Compounds Using Formic Acid: Mild, Efficient, and Versatile
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Developing new efficient catalytic systems to convert abundant and renewable feedstocks into valuable products in a compact, flexible, and target-specific manner is of high importance in modern synthetic chemistry. Here, we describe a versatile set of mild catalytic conditions utilizing a single gold-based solid catalyst that enables the direct and additive-free preparation of four distinct and important amine derivatives (amines, formamides, benzimidazoles, and dimethlyated amines) from readily available formic acid (FA) and nitro starting materials with high level of chemoselectivity. By controlling the stoichiometry of the employed FA, which has attracted considerable interest in the area of sustainable chemistry because of its potential as an entirely renewable hydrogen carrier and as a versatile C1 source, a facile atom- and step-efficient transformation of nitro compounds can be realized in a modular fashion. Renewable formic acid as a flexible feedstock: A versatile heterogeneous gold-based catalytic system has been developed for the controlled, flexible, and target-specific reductive transformation of nitro compounds using stoichiometric equivalents of formic acid as a key starting material under mild and convenient conditions. The overall operational simplicity, high chemoselectivity, functional-group tolerance, and reusability of the catalyst make this approach an attractive and reliable tool for organic and process chemists.
- Yu, Lei,Zhang, Qi,Li, Shu-Shuang,Huang, Jun,Liu, Yong-Mei,He, He-Yong,Cao, Yong
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p. 3029 - 3035
(2015/09/28)
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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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- Method For Preparing Nitrogen Compounds
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The present invention relates to a method for preparing nitrogen compounds using carbon dioxide, and to the use of the method in the production of vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, pesticides, herbicides, antifungal agents and fertilisers. The invention also relates to a method for producing vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, pesticides, herbicides, antifungal agents and fertilisers, which includes a step of preparing nitrogen compounds using the method of the invention. The invention further relates to a method for preparing labelled nitrogen compounds using carbon dioxide and to the uses thereof.
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Paragraph 0192; 0193
(2015/06/03)
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- Au catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO 2/H2
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The gold-catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2 in the presence of H2 was reported, and a series of benzimidazoles were obtained under relatively mild conditions. Several supported Au catalysts including Au/TiO2, Au/Al2O3, Au/ZnO, Au/polyurea and Au/hydrotalcite were examined for the synthesis of benzimidazole from the reaction of 2-nitroaniline with CO2 and H 2, among which Au/TiO2 displayed the best performance. The reaction mechanism was investigated, and it was found that the production of benzimidazole underwent the formation of o-phenylenediamine via the hydrogenation of 2-nitroaniline, followed by the cyclization of o-phenylenediamine with CO2 and H2. This work provides a CO2-involved route for the synthesis of benzimidazoles, which may widen the applications of CO2 in the chemical synthesis. This journal is the Partner Organisations 2014.
- Hao, Leiduan,Zhao, Yanfei,Yu, Bo,Zhang, Hongye,Xu, Huanjun,Liu, Zhimin
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p. 3039 - 3044
(2014/06/10)
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- Convenient two-step one-pot synthesis of benzimidazoles using 2-nitroanilines and thiourea dioxide
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A new convenient method for the conversion of 2-nitroanilines into benzimidazoles by two-step one-pot procedure is reported. The procedure involves the reduction of nitro group followed by the intramolecular cyclisation of the corresponding o-phenylenediamines utilising thiourea dioxide and sodium hydroxide at 70 °C in mixed solvents of H2O and EtOH (v/v, 3/1). The yields are good to excellent and the workup is simple.
- Pu, Shuai,Liang, Qiuxiang,Luo, Xi,Luo, Juan
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p. 118 - 120
(2014/03/21)
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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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p. 3446 - 3448
(2013/05/21)
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- Cyclization of o-phenylenediamines by CO2 in the presence of H2 for the synthesis of benzimidazoles
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The cyclization of o-phenylenediamines by CO2 in the presence of H2 was presented to directly synthesize benzimidazoles, and a series of benzimidazoles were obtained in excellent yields using RuCl 2(dppe)2 as the catalyst.
- Yu, Bo,Zhang, Hongye,Zhao, Yanfei,Chen, Sha,Xu, Jilei,Huang, Changliang,Liu, Zhimin
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supporting information
p. 95 - 99
(2013/02/25)
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- Trimethylsilyl chloride catalyzed synthesis of substituted benzimidazoles using two phase system under microwave conditions, and their antimicrobial studies
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A convenient method using TMSCl (20 mol%) and microwave-induced technique for the synthesis of various benzimidazole is described. This has reduced the reaction time drastically as well as improved the yield when compared to conventional heating. The synthesized compounds were evaluated for their in vitro antibacterial and antifungal activities against four strains each. Preliminary results indicated that, compounds 3e, 3f, 3g, 3k, 3m, 3n and 3o demonstrated very good antimicrobial activity, comparable to the first line standard drugs. The most effective compounds have exhibited activity at MIC of 6.25 μg/mL.
- Karuvalam, Ranjith P.,Haridas, Karickal R.,Shetty, Suchetha N.
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p. 1122 - 1125,4
(2020/08/24)
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- Building heterocyclic systems with RC(OR)2+ carbocations in recyclable bronsted acidic ionic liquids: Facile synthesis of 1-substituted 1H-1,2,3,4-tetrazoles, benzazoles and other ring systems with CH(OEt)3 and EtC(OEt)3 in [EtNH 3][NO3] and [PMIM(SO3H)][OTf]
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1-Aryl/alkyl-1H-1,2,3,4-tetrazoles can conveniently be synthesized in one-pot reactions from the corresponding amines by reaction with TMSN 3 and CH(OEt)3 using the readily available, recyclable, Bronsted acidic ionic liquids [EtNH3][NO3] IL-1 and [PMIM(SO3H)][OTf] IL-2 under mild conditions in high yields. Based on comparative reactions, whereas both ILs are excellent promoters, reactions are completed with shorter reaction times and in higher yields with IL-2. Among 24 examples provided, identical products were obtained via the two ILs, except in the case of 2-aminobenzoic acid where tetrazole was formed with IL-2 and 2-ethylquinazolin-4(3H)-one was formed with IL-1. By leaving out TMS-N 3 from the reaction, the in-situ formed CH(OEt)2 + and EtC(OEt)2+ (via their corresponding orthoesters) react under sonication with o-phenylenediamine bearing various substituents, o-aminothiophenol and o-aminophenol to form a wide array of benzazoles (benzimidazole, benzothiazole and benzoxazole) and quinazolin-4(3H)-one in high yields (18 examples). The two ILs reacted differently in reaction with 2-aminobenzamide, whereas quinazolin-4(3H)one was formed with IL-2/CH(OEt)3, the "unexpected" N-ethylquinazolin-4(3H)one was isolated with IL-1/CH(OEt)3. The latter was also formed from 2-aminobenzoic acid in IL-1/CH(OEt)3. Mechanistic implications are addressed. The reported protocols enable rapid assembly of a host of heterocyclic systems in high yields with the added advantage of recycling and re-use of the ILs.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
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experimental part
p. 2827 - 2835
(2011/06/23)
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- Expeditious and efficient synthesis of benzoxazoles, benzothiazoles, benzimidazoles catalyzed by Ga(OTf)3 under solvent-free conditions
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A new and efficient method for the synthesis of benzoxazoles, benzothiazoles, benzimidazoles from reactions of o-substituted aminoaromatics with orthoesters in the presence of catalytic amounts of Ga(OTf)3 under solvent-free conditions is presented. The remarkable features of this new protocol are high conversion, very short reaction times, cleaner reaction profiles under solvent-free conditions, straight forward procedure, and use of relatively non-toxic catalysts.
- Liu, Juyan,Liu, Qian,Xu, Wei,Wang, Weilu
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experimental part
p. 1739 - 1744
(2012/02/14)
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- Mild and general one-pot reduction and cyclization of aromatic and heteroaromatic 2-nitroamines to bicyclic 2 H -imidazoles
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A one-pot procedure for the conversion of aromatic and heteroaromatic 2-nitroamines into bicyclic 2H-benzimidazoles is described. The procedure employs formic acid, iron powder, and an additive such as NH4Cl to reduce the nitro group and effect the imidazole cyclization with high-yielding conversions generally within one to two hours. The compatibility with a wide range of functionality demonstrates the general utility of this procedure.
- Hanan, Emily J.,Chan, Bryan K.,Estrada, Anthony A.,Shore, Daniel G.,Lyssikatos, Joseph P.
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experimental part
p. 2759 - 2764
(2010/12/25)
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- Ag-TiO2/clay composite photocatalyst for the oxidation-cyclization of 1,2-diamine compounds with propylene glycol or alcohols
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Silver-loaded TiO2 (Ag-TiO2) and acidic clay (K10 montmorillonite) composite photocatalyst has been successfully applied for the light-induced conversion of o-phenylenediamine (OPD) and its derivatives to substituted benzimidazoles with various alcohols in acetonitrile using UV-A and solar light. The influence of the various photocatalysts, solvents, and substituents on the yield and selectivity of the products has been investigated. The mechanism of photocatalysis is proposed. Loading silver on TiO2 enhances product yield and selectivity both in UV and solar light. In the presence of primary alcohols, 2-aminothiophenol forms only disulfide and hence Ag-TiO2/ clay can be used as a green catalyst for the synthesis of disulfides.
- Selvam, Kaliyamoorthy,Annadhasan, Mari,Velmurugan, Rengasamy,Swaminathan, Meenakshisundaram
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experimental part
p. 831 - 837
(2010/09/06)
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- Tetra butyl ammonium chloride catalyzed synthesis of substituted benzimidazoles under microwave conditions
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TBACl (10 mol %) was found to be a useful catalyst for the synthesis of substituted benzimidazoles. The method was proved to be simple, convenient and the product was isolated with good yield.
- Ranjith, P. Karuvalam,Siji,Divia,Karickal, R. Haridas
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experimental part
p. 589 - 593
(2011/01/12)
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