- Synthesis of 2-arylbenzimidazoles under mild conditions catalyzed by a heteropolyacid-containing task-specific ionic liquid and catalyst investigation by electrospray (tandem) mass spectrometry
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A task-specific ionic liquid constituted by a Bronsted acid (1-(3-sulfopropyl)-3-methyl-imidazolium hydrogen sulfate) as the cation, namely MSI, and by [PW12O40]3- as the triply charged counter-anion, namely PW (a heteropolyacid derivative), was used as an efficient catalyst for the condensation reaction between aldehydes and o-phenylenediamines.
- Alvim, Haline G. O.,De Oliveira, Heibbe C. B.,Bataglion, Giovana A.,Eberlin, Marcos N.,Ramos, Luciana M.,Silva, Wender A.
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Read Online
- Synthesis and in vitro α-chymotrypsin inhibitory activity of 6-chlorobenzimidazole derivatives
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A library of benzimidazole derivatives 1–20 were synthesized, and studied for their α-chymotrypsin (α-CT) inhibitory activity in vitro. Kinetics and molecular docking studies were performed to identify the type of inhibition. Compound 1 was found to be a good inhibitor of α-chymotrypsin enzyme (IC50?=?14.8?±?0.1?μM, Ki?=?16.4?μM), when compared with standard chymostatin (IC50?=?5.7?±?0.13?μM). Compounds 2–8, 15, 17, and 18 showed significant inhibitory activities. All the inhibitors were found to be competitive inhibitors, except compound 17, which was a mixed type inhibitor. The substituents (R) in para and ortho positions of phenyl ring B, apparently played a key role in the inhibitory potential of the series. Compounds 1–20 were also studied for their cytotoxicity profile by using 3T3 mouse fibroblast cells and compounds 3, 5, 6, 8, 12–14, 16, 17, 19, and 20 were found to be cytotoxic. Molecular docking was performed on the most active members of the series in comparison to the standard compound, chymostatin, to identify the most likely binding modes. The compounds reported here can serve as templates for further studies for new inhibitors of α-chymotrypsin and other chymotrypsin-like serine proteases enzymes.[Figure presented]
- Siddiqui, Hina,Farooq, Rabia,Marasini, Bishnu P.,Malik, Rizwana,Syed, Naima,Moin, Syed Tarique,Atta-ur-Rahman,Choudhary, M. Iqbal
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Read Online
- 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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- Selective C-C bonds formation, N-alkylation and benzo[d]imidazoles synthesis by a recyclable zinc composite
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Earth abundant metals are much less expensive, promising, valuable metals and could be served as catalysts for the borrowing hydrogen reaction, dehydrogenation and heterocycles synthesis, instead of noble metals. The uniformly dispersed zinc composites were designed, synthesized and carefully characterized by means of XPS, EDS, TEM and XRD. The resulting zinc composite showed good catalytic activity for the N-alkylation of amines with amines, ketones with alcohols in water under base-free conditions, while unsaturated carbonyl compounds could also be synthesized by tuning the reaction conditions. Importantly, it was the first time to realize the synthesis of 2-aryl-1H-benzo[d]imidazole derivatives by using this zinc composite under green conditions. Meanwhile, this zinc catalyst could be easily recovered and reused for at least five times.
- Zhu, Guanxin,Duan, Zheng-Chao,Zhu, Haiyan,Ye, Dongdong,Wang, Dawei
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supporting information
p. 266 - 270
(2021/08/06)
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- Water extract of onion catalyst: An economical green route for the synthesis of 2-substituted and 1,2-disubstituted benzimidazole derivatives with high selectivity
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An efficient, environmental friendly and substrate controlled method of synthesis of 2-substituted benzimidazole derivatives 3 and 1,2-disubstituted benzimidazole derivatives 4 with high selectivity has been achieved from the reaction of o-phenylenediamine 1 and aldehydes 2 in the presence of water extract of onion and selecting suitable reaction medium. This method is widely applicable for variety of aldehydes such as aromatic/aliphatic/heterocyclic aldehydes and 1,2-diamines to afford 2-substituted benzimidazole derivatives 3 and 1,2-disubstituted benzimidazole derivatives 4 in good to excellent yields (up to 96%). The developed method of water extract of onion catalysis produced 2-substituted benzimidazoles 3 from aromatic aldehydes having electron-withdrawing groups, whereas aromatic aldehydes bearing electron donating groups selectively furnished 1,2-disubstituted benzimidazole 4 derivatives. The process described here has several advantages of cheap, low energy consumption, commercially available starting materials, operational simplicity and nontoxic catalyst. The use of water extract of onion makes this present methodology green and giving a useful contribution to the existing methods available for the preparation of benzimidazole derivatives. In addition, Hammett correlation of substituent constant (σ) vs percentage (%) yield has been established.
- Kaliyan, Prabakaran,Selvaraj, Loganathan,Muthu, Seenivasa Perumal
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supporting information
p. 340 - 349
(2020/12/01)
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- Visible-Light-Induced Deaminative Alkylation/Cyclization of Alkyl Amines with N-Methacryloyl-2-phenylbenzoimidazoles in Continuous-Flow Organo-Photocatalysis
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Herein, we present a metal-free visible-light-induced eosin-y-catalyzed deaminative strategy for the sequential alkylation/cyclization of N-methacryloyl-2-phenylbenzoimidazoles with alkyl amine-derived Katritzky salts, which provides an efficient avenue for the construction of various benzo[4,5]imidazo[2,1-a]isoquinolin-6(5H)-one derivatives in moderate to excellent yields under mild reaction conditions. The key enabling feature of this novel reaction includes utilization of redox-active pyridinium salts from abundant and inexpensive primary amine feedstocks that were converted into alkyl radicals via C-N bond scission and subsequent alkylation/cyclization with N-methacryloyl-2-phenylbenzoimidazoles by the formation of two new C-C bonds. In addition, we implemented this protocol for a variety of amino acids, affording the products in moderate yields. Moreover, the novel, environmentally benign batch protocol was further carried out in a continuous-flow regime by utilizing a perfluoroalkoxy alkane tubing microreactor under optimized reaction conditions with a blue light-emitting diode light source, enabling excellent yields and a shorter reaction time (19 min) versus the long reaction time (16 h) of the batch reaction. The reaction displays excellent functional group tolerance, easy operation, scalability, mild reaction conditions, and broad synthetic utility.
- Ramesh, Vankudoth,Gangadhar, Maram,Nanubolu, Jagadeesh Babu,Adiyala, Praveen Reddy
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supporting information
p. 12908 - 12921
(2021/09/18)
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- A heterogeneous catalytic strategy for facile production of benzimidazoles and quinoxalines from primary amines using the Al-MCM-41 catalyst
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This study reports a straightforward heterogeneous catalytic (Al-MCM-41) approach to synthesize nitrogen heterocycle moieties from primary amines under solvent-free conditions. The Al-MCM-41 catalyst was prepared using a hydrothermal method and characterized by various analytical techniques. The probability and limitations of the catalytic methodology were presented with various substrates. The catalytic method grants an attractive route to a wide variety of benzimidazole and quinoxaline moieties with good to excellent yields. The gram scale reaction and reusability (up to five cycles) of the Al-MCM-41 catalyst would greatly benefit industrial applications. This journal is
- Vasu, Amrutham,Naresh, Mameda,Krishna Sai, Gajula,Divya Rohini, Yennamaneni,Murali, Boosa,Ramulamma, Madasu,Ramunaidu, Addipilli,Narender, Nama
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p. 9439 - 9446
(2021/12/09)
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- α-Keto Acids as Triggers and Partners for the Synthesis of Quinazolinones, Quinoxalinones, Benzooxazinones, and Benzothiazoles in Water
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A general and efficient method for the synthesis of quinazolinones, quinoxalinones, benzooxazinones, and benzothiazoles from the reactions of α-keto acids with 2-aminobenzamides, benzene-1,2-diamines, 2-aminophenols, and 2-aminobenzenethiols, respectively, is described. The reactions were conducted under catalyst-free conditions, using water as the sole solvent with no additive required, and successfully applied to the synthesis of sildenafil. More importantly, these reactions can be conducted on a mass scale, and the products can be easily purified through filtration and washing with ethanol (or crystallized).
- Huang, Jian,Chen, Wei,Liang, Jiazhi,Yang, Qin,Fan, Yan,Chen, Mu-Wang,Peng, Yiyuan
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p. 14866 - 14882
(2021/10/25)
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- Nickel catalyzed sustainable synthesis of benzazoles and purines: Via acceptorless dehydrogenative coupling and borrowing hydrogen approach
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Herein we report nickel-catalyzed sustainable synthesis of a few chosen five-membered fused nitrogen heterocycles such as benzimidazole, purine, benzothiazole, and benzoxazole via acceptorless dehydrogenative functionalization of alcohols. Using a bench stable, easy to prepare, and inexpensive Ni(ii)-catalyst, [Ni(MeTAA)] (1a), featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)), a wide variety of polysubstituted benzimidazole, purine, benzothiazole, and benzoxazole derivatives were prepared via dehydrogenative coupling of alcohols with 1,2-diaminobenzene, 4,5-diaminopyrimidine, 2-aminothiphenol, and 2-aminophenol, respectively. A wide array of benzimidazoles were also prepared via a borrowing hydrogen approach involving alcohols as hydrogen donors and 2-nitroanilines as hydrogen acceptors. A few control experiments were performed to understand the reaction mechanism.
- Chakraborty, Gargi,Guin, Amit Kumar,Mondal, Rakesh,Paul, Nanda
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p. 7217 - 7233
(2021/08/30)
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- Functional POM-catalyst for selective oxidative dehydrogenative couplings under aerobic conditions
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Development of selective and efficient reusable catalytic systems for sustainable chemical production under benign conditions is attractive and received much attention. Herein, we report a rod-shaped octadecyl trimethylammonium functionalized Keggin-type polyoxometalate [PMO12O40] hybrids (OTA-POM) as an efficient heterogeneous catalyst for selective oxidative dehydrogenative couplings under aerobic conditions without any additive or external base. The catalyst recovery and subsequent five successive recyclability studies of hybrid POM confirms the heterogeneous nature of present catalytic system.
- Samaraj, Elavarasan,Balaraman, Ekambaram,Manickam, Sasidharan
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- Solvent-dependent metal-free chemoselective synthesis of benzimidazoles and 1,3,5-triarylbenzenes from 2-amino anilines and aryl alkyl ketones catalyzed by I2
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A solvent-dependent I2-catalyzed chemoselective reaction was developed for the synthesis of benzimidazoles and 1,3,5-triarylbenzenes via the annulation of 2-amino anilines and aryl alkyl ketones or the cyclization of aryl alkyl ketones, respectively. With 1,4-dioxane as the solvent, sequential C[sbnd]N bond formation followed by C(CO)-C(CH3) bond cleavage leads to the formation of benzimidazoles in a highly selective manner while aldol-type self-condensation of aryl alkyl ketones predominates using PhNO2 or PhCl as the solvent to afford 1,3,5-triarylbenzenes.
- Ding, Yuxin,Ma, Renchao,Ma, Yongmin
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supporting information
(2021/04/09)
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- ARYL HYDROCARBON RECEPTOR ACTIVATORS
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Small molecule AhR ligands are disclosed. The ligands can induce the differentiation of Tr1 cells to suppress pathogenic immune responses without inducing nonspecific immune suppression. Methods of treatment of autoimmune diseases using the AhR ligands are also disclosed.
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Page/Page column 31-32
(2021/02/05)
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- Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
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We report the tetramethyl ammonium hydroxide catalyzed oxidative coupling of amines and alcohols for the synthesis of imines under metal-free conditions by utilizing oxygen from air as the terminal oxidant. Under the same conditions, with ortho-phenylene diamines and 2-aminobenzenethiols the corresponding benzimidazoles and benzothiazoles were obtained. Quinoxalines were obtained from ortho-phenylene diamines and 1-phenylethane-1,2-diol, the conditions were then extended to the synthesis of quinoline building blocks by reaction of 2-amino benzyl alcohols either with 1-phenylethan-1-ol or acetophenone derivatives. The formation of C?N, C?S and C?C bonds was achieved under metal-free conditions. A broad range of amines (aromatic, aliphatic, cyclic and heteroaromatic) as well as benzylic alcohols including heteroaryl alcohols reacted smoothly and provided the desired products. The mild reaction conditions, commercially available catalyst, metal-free, good functional-group tolerance, broad range of products (imines, benzimidazoles, benzothiazoles, quinoxalines and quinolines) and applicability at gram scale reactions are the advantages of the present strategy.
- Adimurthy, Subbarayappa,Badhani, Gaurav,Joshi, Abhisek
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p. 6705 - 6716
(2021/12/31)
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- A one-pot synthesis of benzimidazoles via aerobic oxidative condensation of benzyl alcohols with o-phenylenediamines catalyzed by [MIMPs]+Cl-/NaNO2/TEMPO
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The ionic liquid 1-methyl-3-(3-sulfopropyl)imidazolium chloride ([MIMPs]+Cl-) in combination with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and sodium nitrite (NaNO2) as a catalytic system demonstrates high efficiency in the one-pot two-step aerobic oxidative condensation of benzyl alcohols with 1,2-phenylenediamines to give benzimidazoles. Various benzimidazoles are obtained in good to excellent yields by this strategy.
- Geng, Zhenzhen,Zhang, Hong-Yu,Yin, Guohui,Zhang, Yuecheng,Zhao, Jiquan
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p. 557 - 565
(2020/03/30)
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- New synthesis method of thiabendazole
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The invention relates to a new synthetic route of a drug commonly named as thiabendazole. Thiazole-4-formaldehyde is used as a raw material, and is condensed with hydroxylamine hydrochloride to obtainthiazole-4-formaldoxime, thiazole-4-formaldoxime is subjected to chlorination by using NCS, and then reacts with aniline to obtain N-phenylthiazole-4-methylamine oxime, then N-phenylthiazole-4-methylamine oxime reacts with p-trifluoromethyl benzoyl chloride to obtain an amidoxime ester, and finally a visible-light-catalyzed free radical reaction is adopted for cyclization to obtain thiazole. According to the method, the visible-light-catalyzed free radical reaction is used to the synthesis of thiabendazole for the first time, the reaction conditions of a high temperature and a strong acid inthe traditional synthesis method are avoided, and thereby the reaction is greener and milder. The method has a broad spectrum, and can also be used for synthesis of imidazole compounds Ia-Ial.
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Paragraph 0026; 0035; 0036; 0037; 0038; 0196; 0197
(2020/02/20)
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- Nickel catalysed construction of benzazoles: Via hydrogen atom transfer reactions
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Herein we report a homogeneous, phosphine free, inexpensive nickel catalyst that forms a wide variety of benzazoles from alcohol and diamines by a reaction sequence of alcohol oxidation, imine formation, ring cyclization and dehydrogenative aromatization. A reversible azo/hydrazo couple, that is part of the ligand architecture steers both the alcohol oxidation and dehydrogenation of the annulated amine under fairly mild reaction conditions. Interestingly, both the alcohol oxidation and amine dehydrogenation steps are directly mediated by hydrogen atom transfer (HAT), which is greatly facilitated by the reduced ligand backbone. The kH/kD for the amine dehydrogenation step, measured at 60 °C is 5.9, fully consistent with HAT as the rate determining factor during this step. This is a unique scenario where two consecutive oxidation steps towards benzazole formation undergo HAT, which has been substantiated via kinetic studies, KIE determination and intermediate isolation. This journal is
- Adhikari, Debashis,Bains, Amreen K.,Dey, Dhananjay,Kundu, Abhishek,Yadav, Sudha
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p. 6495 - 6500
(2020/11/13)
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- Preparation method of 2-aryl benzimidazole compound
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The invention discloses a preparation method of a 2-aryl benzimidazole compound. The preparation method comprises the following steps: (1) adding a cyanobenzene compound, an o-phenylenediamine compound, an alkali, a catalyst and an organic solvent into a reactor for reaction; and (2) after the reaction is finished, cooling, removing the solvent, extracting, washing, drying, filtering, and removingthe solvent to obtain a target product; and (3) purifying the target product by column chromatography to obtain the 2-aryl benzimidazole compound. According to the method, the defect that a large amount of acid and a complex metal catalyst system need to be used in a traditional method is overcome, the reaction condition is mild, the severe condition that high temperature is needed in the reaction is avoided, the catalyst is cheap and easy to obtain, the preparation cost is greatly reduced, energy consumption is reduced, the method is simple, and the product yield is high.
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Paragraph 0050-0054
(2020/07/15)
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- Benzimidazoles and benzothiazoles from styrenes and N-vinylimidazole via palladium catalysed oxidative C[dbnd]C and C[sbnd]N bond cleavage
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Herein we report a first, palladium catalyzed, one-pot methodology for the synthesis of pharmacologically important benzimidazoles and benzothiazoles from readily available terminal aromatic olefins. The process involves sequential C[dbnd]C/C[sbnd]N bond cleavage followed by C[sbnd]N/C[sbnd]S bond formation.
- Shaikh, Altab,Ravi, Owk,Pushpa Ragini,Sadhana, Nimma,Reddy Bathula, Surendar
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- 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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- Formation of Amidinyl Radicals via Visible-Light-Promoted Reduction of N-Phenyl Amidoxime Esters and Application to the Synthesis of 2-Substituted Benzimidazoles
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We have developed a new method for the synthesis of 2-substituted benzimidazoles via amidinyl radicals generated by visible-light-promoted reduction of N-phenyl amidoxime esters in the presence of an iridium photocatalyst. This is the first report of the use of N-phenyl amidoxime esters as amidinyl radical precursors, and the first use of substituted benzene rings as amidinyl radical acceptors. This method widens the application range of substrates and overcomes the shortcomings of the traditional methods for the synthesis of 2-substituted benzimidazoles, which requires harsh reaction conditions, involves difficult-to-prepare substituted o-phenylenediamine substrates, and produces acidic waste.
- Li, Gang,He, Ru,Liu, Qiang,Wang, Ziwen,Liu, Yuxiu,Wang, Qingmin
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p. 8646 - 8660
(2019/07/08)
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- Iron-catalyzed one-pot sequential transformations: Synthesis of quinazolinones via oxidative Csp3–H bond activation using a new metal-organic framework as catalyst
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A new mixed-linker iron-based MOF VNU-21 [Fe3(BTC)(EDB)2·12.27H2O] was synthesized via mixed-linker synthetic strategy using 1,3,5-benzenetricarboxylic acid, 4,4′-ethynylenedibenzoic acid, and FeCl2. The VNU-21 was consequently used as a recyclable heterogeneous catalyst in the one-pot synthesis of quinazolinones via two steps under oxygen atmosphere. The synthetic scheme involved iron-catalyzed oxidative Csp3–H bond activation to achieve decarboxylation of phenylacetic acids, and succeeding metal-free oxidative cyclization with 2-aminobenzamides. The VNU-21 was more effective than a series of heterogeneous and homogeneous catalysts. It was possible to reutilize the iron-based framework without a considerable deterioration in catalytic performance. To our best knowledge, this one-pot synthesis of quinazolinones was not previously performed using a recyclable catalyst.
- To, Tuong A.,Vo, Yen H.,Nguyen, Hue T.T.,Ha, Phuong T.M.,Doan, Son H.,Doan, Tan L.H.,Li, Shuang,Le, Ha V.,Tu, Thach N.,Phan, Nam T.S.
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- Visible-light-induced condensation cyclization to synthesize benzimidazoles using fluorescein as a photocatalyst
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A mild strategy for visible-light-induced synthesis of benzimidazoles was developed using aromatic aldehydes and o-phenylenediamines as substrates. The use of an organic dye, fluorescein, as an innoxious photocatalyst provided a mild and inexpensive catalytic system to synthesize a series of benzimidazoles in moderate to excellent yields. It was originally applied to this system to obtain benzimidazoles. Besides, the catalytic system does not require an additional oxidant or metal which was good for the environment.
- Li, Zhuofei,Song, He,Guo, Rui,Zuo, Minghui,Hou, Chuanfu,Sun, Shouneng,He, Xin,Sun, Zhizhong,Chu, Wenyi
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p. 3602 - 3605
(2019/07/09)
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- Method used for rapid preparation of benzo-heterocycle compound with physical grinding under solvent-free room temperature conditions
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The invention discloses a method used for rapid preparation of benzo-heterocycle compound with physical grinding under solvent-free room temperature conditions. According to the method, glacial aceticacid is taken as a catalyst; at solvent-free room temperature conditions, physical grinding is adopted, reaction of 2-substituted arylamines (2-mercapto arylamine, 2-aminophenol, and o-phenylenediamine) and aromatic aldehydes is carried out using physical grinding. The method is friendly to the environment, is simple in operation, is safe, is low in cost, and is high in efficiency. Compared withthe prior art, the advantages are that: the method is suitable for a large amount of functional groups, yield is high, less by-product is generated, operation is simple, the method is safe, cost is low, and the method is friendly to the environment.
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Paragraph 0018; 0059
(2019/01/21)
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- A niobium-catalyzed coupling reaction of α-keto acids with: Ortho -phenylenediamines: Synthesis of 3-arylquinoxalin-2(1 H)-ones
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A general methodology to access valuable 3-arylquinoxalin-2(1H)-ones was developed, by the reaction of α-keto acids with ortho-phenylenediamines in the presence of ammonium niobium oxalate (ANO) as a catalyst. The reactions were conducted in only 10 min under ultrasonic irradiation as an alternative energy source, affording water as the only co-product. A total of twenty-three different 3-arylquinoxalin-2(1H)-ones were selectively obtained in good to excellent yields by this atom-efficient protocol. Additionally, 1H-15N HMBC experiments were used to reveal the regioisomerism of the obtained products.
- Ebersol, Camila,Rocha, Nicole,Penteado, Filipe,Silva, Márcio S.,Hartwig, Daniela,Lenard?o, Eder J.,Jacob, Raquel G.
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supporting information
p. 6154 - 6160
(2019/11/20)
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- Cobalt-Catalyzed Sustainable Synthesis of Benzimidazoles by Redox-Economical Coupling of o-Nitroanilines and Alcohols
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This study reveals cobalt-catalyzed sustainable synthesis of benzimidazoles by redox-economical coupling of o-nitroanilines and alcohols. The major advantage of this report is the use of a commercially available cheap cobalt catalyst to produce a wide variety of 2-substituted benzimidazoles by hydrogen autotransfer without using any additional external redox reagent and costly ligand system. A thorough mechanistic insight of the reaction is proposed by performing a series of control experiments.
- Das, Sanju,Mallick, Samrat,De Sarkar, Suman
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p. 12111 - 12119
(2019/10/02)
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- Enhanced Catalytic Properties of Molybdenum Promoted Mesoporous Cobalt Oxide: Structure-Surface-Dependent Activity for Selective Synthesis of 2-Substituted Benzimidazoles
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High-valent molybdenum ions were substituted into the cobalt oxide lattice through a one step, sol-gel method and investigated for selective synthesis of 2-substituted benzimidazoles. Catalyst synthesis involves surfactant assisted soft templating inverse micelle method, which forms mesopores by interconnected intraparticle voids. Substitutional doping of Mo6+ resulted in materials with modified structural, morphological, surface, and redox properties. The catalytic activity increased with Mo concentration until an optimum amount (3 % Mo incorporation). Modified material shows lattice expansion, increased surface oxygen vacancies, and high surface area, which are responsible for the higher catalytic activity in selective benzimidazole synthesis reaction. A strong correlation between surface properties of the catalyst and the product selectivity was observed and plausible mechanistic and kinetic data are proposed and collected, respectively.
- Weerakkody, Chandima,Rathnayake, Dinithi,He, Junkai,Dutta, Biswanath,Kerns, Peter,Achola, Laura,Suib, Steven L.
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p. 528 - 537
(2018/09/25)
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- Method for catalytically synthesizing benzimidazole compound by organic protonic acid under condition of no solvent
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The invention discloses a method for catalytically synthesizing a benzimidazole compound by organic protonic acid under the condition of no solvent. According to the method provided by the invention,high efficiency catalysis is carried out to rapidly prep
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Paragraph 0015; 0062
(2018/11/27)
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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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- Diphosphorus tetraiodide (P2I4): An efficient catalyst for synthesis of 2-Aryl-1,3-benzazoles via cyclocondensation of o-Amino/Mercaptan/Hydroxy anilines with aryl acids
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An efficient and versatile approach for the synthesis of 2-substituted 1,3-benzazoles has been developed via diphosphorus tetraiodide (P2I4) catalyzed condensation reaction of ortho-substituted anilines (–NH2, –SH and –OH) with various aromatic acids to give benzimidazoles, benzothiazoles and benzoxazoles in excellent yields. Additionally, the synthetic approach reported herein has advantages such as mild reaction conditions, broad substrate scopes as well as simple one-pot operation, common for all the three 1,3-benzazoles, which makes this strategy highly attractive.
- Bhagat, Saket B.,Sutar, Yogesh B.,Manohar, Yogesh,Telvekar, Vikas N.
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p. 376 - 380
(2018/01/11)
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- Air-stable Ruthenium(II)-NNN Pincer Complexes for the Efficient Coupling of Aromatic Diamines and Alcohols to 1H-benzo[d]imidazoles with the Liberation of H2
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Two new phosphine-free RuII-NNN pincer complexes ([RuCl(L1)(CH3CN)2]Cl (1) and [RuCl(L2)(CH3CN)2]Cl (2) [L1=2,6-bis(1H-imidazole-2-yl)pyridine, L2=2,6-bis(1-hexyl-1H-imidazole-2-yl)pyridine] were synthesized to catalyze the condensation of benzyl alcohol and benzene-1,2-diamine homogeneously to 2-pheny-1H-benzo[d]imidazole and H2. The reactivity in the order of 1>2 is lower than that of the phosphine-containing RuII-NNN pincer complex [RuCl2(L1)(PPh3)3] (3), and thus a homogeneous system that contained 1, 1 equivalent of 1,2-bis(diphenylphosphanyl)ethane, and 10 equivalents of NaBPh4 was developed to improve the catalytic efficiency for the condensation of primary alcohols and benzene-1,2-diamine (or its derivatives) to 2-substituted 1H-benzo[d]imidazoles in excellent yields (up to 97 %) and turnover numbers (388). This system can be used to realize the facile one-step synthesis of 1H-benzo[d]imidazole derivatives from alcohols without the use of an oxidant and/or a stoichiometric amount of inorganic base that is usually necessary in homogeneous systems reported previously.
- Li, Lin,Luo, Qi,Cui, Huahua,Li, Renjie,Zhang, Jing,Peng, Tianyou
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p. 1607 - 1613
(2018/02/28)
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- C-N Bond Formation Catalyzed by Ruthenium Nanoparticles Supported on N-Doped Carbon via Acceptorless Dehydrogenation to Secondary Amines, Imines, Benzimidazoles and Quinoxalines
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Ruthenium nanoparticles (NPs) supported on N-doped carbon (Ru/N?C) were prepared by the pyrolysis of cis-Ru(phen)2Cl2 loaded onto carbon powder (VULCAN XC72R) at 800 °C. Ru/N?C NPs (0.2 mol% Ru) selectively catalyzed either acceptorless dehydrogenation coupling (ADC) or auto-transfer-hydrogen (ATH) reactions of amines with alcohols to imines and secondary amines. Such selectivity could be controlled by the choice of alkali metal ion associated with the base. Under similar catalytic conditions, the ADC cross-coupling of diamines with primary alcohols or diols afforded the corresponding benzimidazoles and quinoxalines in good to excellent yields. This catalytic system displayed good activity, recyclability, and wide applicability to a diverse range of substrates.
- Guo, Bin,Li, Hong-Xi,Zhang, Shi-Qi,Young, David James,Lang, Jian-Ping
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p. 5627 - 5636
(2018/12/04)
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- Microwave-Assisted Nickel-Catalyzed Synthesis of Benzimidazoles: Ammonia as a Cheap and Nontoxic Nitrogen Source
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An efficient and convenient Ni-catalyzed C-N bond formation for the synthesis of various benzimidazoles from various 2-haloanilines, aldehydes, and ammonia in a concise manner is reported. This protocol uses commercially available, nonhazardous, clean ammonia as a reaction partner instead of other nitrogen sources. Benzimidazoles, as the sole products, were obtained in high to excellent yields (up to 95%).
- Ke, Fang,Zhang, Peng,Xu, Yiwen,Lin, Xiaoyan,Lin, Jin,Lin, Chen,Xu, Jianhua
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supporting information
p. 2722 - 2726
(2018/12/14)
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- Synthesis of benzimidazoles by Cul-catalyzed three-component reaction of 2-haloaniline, ammonia and aldehyde in water
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An efficient copper-catalyzed three-component reaction of 2-haloaniline, ammonia and aldehyde for the synthesis of benzimidazoles with 1,10-phenanthroline as the ligand has been developed. A variety of substituted benzimidazole derivatives can be obtained in yields up to 95%.
- Ke, Fang,Zhang, Peng,Lin, Chen,Lin, Xiaoyan,Xu, Jianhua,Zhou, Xiangge
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supporting information
p. 8090 - 8094
(2018/11/23)
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- Eco-friendly highly efficient solvent free synthesis of benzimidazole derivatives over sulfonic acid functionalized graphene oxide in ambient condition
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Abstract: Sulfonated graphene oxide (GO-HSO3) heterogeneous catalyst was prepared at molecular level and characterized by using various modern analytic and spectroscopic methods. Using prepared heterogeneous catalyst GO-HSO3, benzimidazole synthesis was carried out by means of reacting diamine and aldehyde at room temperature in solvent free condition. The catalyst GO-HSO3 showed tremendous catalytic activity in selective synthesis of benzimidazole, as a result 100?% conversion of reactants and up to 89.0?% yield of respective benzimidazole was achieved using 0.1?mg of catalyst in very short reaction duration. The GO-HSO3 catalyst was separated from the reaction mixture by simple filtration process at the end of reaction and reused for six successive cycles without noteworthy loss of catalytic activity and selectivity. Key advantageous of this protocol is high yield, low cost, and easy work-up procedure as well as short reaction time and solvent free condition. The present method is found eco-friendly, highly efficient, solvent free, high yielding, and clean method for the synthesis benzimidazole derivatives at room temperature. Graphical Abstract: [Figure not available: see fulltext.]
- Swami, Mantosh B.,Jadhav, Arvind H.,Mathpati, Sushil R.,Ghuge, Hanmant G.,Patil, Sudhakar G.
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p. 2033 - 2053
(2017/03/22)
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- Oxidative Synthesis of Benzimidazoles, Quinoxalines, and Benzoxazoles from Primary Amines by ortho-Quinone Catalysis
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The bioinspired ortho-quinone catalysts have been applied to heterocycles synthesis. Without any metal cocatalysts, a sole ortho-quinone catalyst enables the oxidative synthesis of benzimidazoles, quinoxalines and benzoxazoles from primary amines in high yields under mild conditions with oxygen as the terminal oxidant.
- Zhang, Ruipu,Qin, Yan,Zhang, Long,Luo, Sanzhong
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supporting information
p. 5629 - 5632
(2017/10/25)
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- Method for catalytically synthesizing benzimidazole compound in water phase under microwave radiation
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The invention discloses a method for catalytically synthesizing a benzimidazole compound in a water phase under microwave radiation. The method comprises the following steps: adding a catalytic amount of metal chloride, proline lithium and a substituted 2-halogenated aniline substrate, ammonia water, a benzaldehyde derivative, inorganic alkali and water into a reaction container; putting the reaction container into a microwave reaction instrument to react at certain temperature and under certain power; after certain time, decompressing and concentrating; purifying a product through a column chromatography to obtain the benzimidazole compound, wherein the metal chloride in the step is iron chloride, cobalt chloride, nickel chloride or copper chloride, the inorganic alkali in the step is sodium hydroxide, cesium carbonate, sodium carbonate, potassium hydroxide or potassium phosphate, and reaction temperature of the microwave reaction instrument is 20 DEG C to 200 DEG C. The method for preparing the benzimidazole compound, provided by the invention, is environmental-friendly, is simple and convenient to operate, is safe and cheap and is efficient. Compared with the prior art, the method has the advantages of moderate reaction conditions, simplicity in operation, high yield, safety, low cost and environmental friendliness.
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Paragraph 0066
(2017/07/19)
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- Denitrogenative Imidoyl Radical Cyclization: Synthesis of 2-Substituted Benzoimidazoles from 1-Azido-2-isocyanoarenes
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A novel access to 2-substituted benzoimidazoles, through unprecedented denitrogenative imidoyl radical cyclization of 1-azido-2-isocyanoarenes, has been developed. This tandem radical process was initiated by adding a C- or P-centered radical to isocyanide, followed by cycloaddition of the imidoyl radical to the azido group. Then, nitrogen loss and hydrogen abstraction of the resulting aminyl radical from surroundings delivered 2-substituted benzoimidazoles. Carbon radicals generated from another annulation process could also be applied, furnishing various heterocycle linked benzoimidazole derivatives.
- Li, Dengke,Mao, Tingting,Huang, Jinbo,Zhu, Qiang
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supporting information
p. 3223 - 3226
(2017/06/23)
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- Copper-Catalyzed Double C-N Bond Formation for the Synthesis of Diverse Benzimidazoles from N -Alkyl-2-iodoaniline and Sodium Azide
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An efficient approach to the synthesis of benzimidazole derivatives has been achieved by copper-catalyzed double C-N bonds formation of N-alkyl-2-iodoaniline and sodium azide. The reaction was supposed to proceed through copper-catalyzed tandem reaction of SNAr reaction, aerobic oxidation of C(sp3)-H bond and intramolecular C-N bond formation sequence. Structurally diverse 2-aryl, alkenyl and alkyl benzoimidazole derivatives were assembled by this methodology.
- Chen, Zhengkai,Li, Hongli,Cao, Gangjian,Xu, Jianfeng,Miao, Maozhong,Ren, Hongjun
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supporting information
p. 504 - 508
(2017/02/24)
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- Oxidant-free synthesis of benzimidazoles from alcohols and aromatic diamines catalysed by new Ru(II)-PNS(O) pincer complexes
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Benzimidazoles are chemically and pharmaceutically important, and an environmentally benign synthetic method based on acceptorless dehydrogenative condensation of primary alcohols and benzene-1,2-diamine is developed in this work. Three Ru(ii) hydride complexes [RuHCl(CO)(PNS(O))] (containing two isomers 1a and 1b) and [RuHCl(CO)(PPh3)(SNCNHC)]PF6 (2) based on two new quinoline-based ligands 2-(diphenylphosphanylmethyl)-8-phenylsulfinylquinoline (PNS(O)) and 1-mesityl-3-(8-phenylthioquinolyl-2-methyl)-2-imidazole carbene (SNCNHC) are prepared and fully characterized. These complexes catalyse the condensation of benzyl alcohol and benzene-1,2-diamine to 2-phenylbenzimidazole with the liberation of H2, and the catalytic activity follows the order: 1a ≈ 1b > 2. When 0.2 mol% of 1a and 2 mol% of NaBPh4 were used, various 2-functionalized benzimidazoles were obtained in good yields (70-85%) and high turnover numbers (TONs ~ 425). This homogeneous system does not need oxidants or stoichiometric strong bases (KOH or KOtBu, etc.) that are normally used in the reported homogeneous systems, and thus is a greener process.
- Luo, Qi,Dai, Zengjin,Cong, Hengjiang,Li, Renjie,Peng, Tianyou,Zhang, Jing
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p. 15012 - 15022
(2017/11/14)
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- Br?nsted acid-catalyzed metal-free one-pot synthesis of benzimidazoles via [4+1] heteroannulation of ortho-phenylenediamines with β-oxodithioesters
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An operationally simple and user-friendly one-pot domino protocol for the synthesis of 2-aryl/hetaryl benzimidazoles has been devised from easily available and inexpensive 1,2-phenylenediamines and β-oxodithioesters. The strategic [4+1] heteroannulation i
- Srivastava, Abhijeet,Shukla, Gaurav,Yadav, Dhananjay,Singh, Maya Shankar
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- Tunable Triazole-Phosphine-Copper Catalysts for the Synthesis of 2-Aryl-1H-benzo[d]imidazoles from Benzyl Alcohols and Diamines by Acceptorless Dehydrogenation and Borrowing Hydrogen Reactions
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Triazole-phosphine-copper complexes (TAP?Cu) have been synthesized and applied as tunable and efficient catalysts for the selective synthesis of fluoro-substituted 2-aryl-1H-benzo[d]imidazole and 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives from simple alcohols in only one step. TAP?Cu exhibited excellent and tunable catalytic activity for both dehydrogenation and borrowing hydrogen reactions with more than 80 examples being demonstrated for the first time. It was observed that the ligand played a critical role in catalyst activity. Mechanistic studies and deuterium labeling experiments indicated that the reactions proceeded by an initial and reversible alcohol dehydrogenation resulting in a copper hydride intermediate. This was also supported by the direct observation of a diagnostic copper hydride signal by solid-state infrared spectroscopy. The TAP?Cu-H complex showed absorptions at 912 cm?1 that could be assigned to copper?hydride stretches. Furthermore, the direct trapping of an intermediate bisimine was also successfully performed. (Figure presented.).
- Xu, Zhaojun,Wang, Duo-Sheng,Yu, Xiaoli,Yang, Yongchun,Wang, Dawei
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supporting information
p. 3332 - 3340
(2017/10/06)
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- Iodine-Mediated Aryl C?H Amination for the Synthesis of Benzimidazoles and Pyrido[1,2-a]benzimidazoles
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An intramolecular aryl C?H amination reaction has been achieved using molecular iodine as the sole oxidant for the synthesis of benzimidazole derivatives. The required substrates were readily prepared by addition or coupling of arylamines with the corresponding nitriles or aryl iodides. Iodine-mediated oxidative cyclization of these substrates in the presence of potassium carbonate (K2CO3) as base afforded the corresponding products in moderate to good yields. The transition metal-free protocol presented here is insensitive to air and operationally simple. This versatile and eco-friendly synthetic methodology is broadly applicable to a variety of N-aryl-substituted amidines and pyridin-2-amines, and provides direct access to both 1H-benzo[d]imidazole and pyrido[1,2-a]benzimidazole derivatives from the corresponding precursors. (Figure presented.).
- Lv, Zhigang,Liu, Jing,Wei, Wei,Wu, Jie,Yu, Wenquan,Chang, Junbiao
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p. 2759 - 2766
(2016/09/13)
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- Selective exploitation of acetoacetate carbonyl groups using imidazolium based ionic liquids: synthesis of 3-oxo-amides and substituted benzimidazoles
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An unprecedented Br?nsted base ionic liquid tuned selective aminolysis of ester carbonyl of acetoacetates is demonstrated to achieve acetoacetamide derivatives. Other imidazolium ionic liquid performs an efficient cyclization catalysis involving acetoacetate-carbonyl groups and o-phenylenediamine at elevated temperature to produce benzimidazoles via C–C bond cleavage of intermediate 1,5-benzodiazepinones under solvent-free conditions.
- Chakraborty, Ankita,Majumdar, Swapan,Maiti, Dilip K.
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p. 3298 - 3302
(2016/07/11)
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- Silica–ferric chloride (SiO2–FeCl3) catalyzed selective synthesis of 2-substituted benzimidazole through Csp2Csp3bond cleavage of β-ketoester/amide
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Silica–ferric chloride (SiO2–FeCl3) supported reagent was successfully utilized as recyclable catalyst for the general and highly efficient synthesis of 2-substituted benzimidazole by the condensation of 1,2-diamino benzene and β-ketoester/amide followed by original Csp2Csp3bond cleavage. Evidences in favor of C[sbnd]C (α–β) bond cleavage of β-ketoesters/amides are established.
- Majumdar, Swapan,Chakraborty, Ankita,Bhattacharjee, Subrata,Debnath, Sudipto,Maiti, Dilip K.
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supporting information
p. 4595 - 4598
(2016/09/23)
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- Copper(II)-Catalyzed Oxidative Cross-Coupling of Anilines, Primary Alkyl Amines, and Sodium Azide Using TBHP: A Route to 2-Substituted Benzimidazoles
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Copper(II)-catalyzed oxidative cross-coupling of anilines, primary alkyl amines, and sodium azide is described in the presence of TBHP at moderate temperature. This one-pot multicomponent protocol involves a domino C-H functionalization, transimination, ortho-selective amination, and a cyclization sequence. The broad substrate scope and functional group compatibility are the significant practical features. The protocol can be extended to the coupling of benzyl alcohols with moderate yields.
- Mahesh, Devulapally,Sadhu, Pradeep,Punniyamurthy, Tharmalingam
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p. 3227 - 3234
(2016/05/19)
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- Decarboxylative Coupling of α-Keto Acids with ortho-Phenylenediamines Promoted by an Electrochemical Method in Aqueous Media
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An electrochemical method for the decarboxylative coupling of α-keto acids with ortho-phenylenediamines was developed. The reaction proceeded smoothly in aqueous solution under air and metal catalyst-free conditions to afford 2-substituted benzimidazoles in good yields. Benzothiazoles could also be synthesized by this protocol. (Figure presented.) .
- Wang, Hai-Bin,Huang, Jing-Mei
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supporting information
p. 1975 - 1981
(2016/07/06)
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- Iron-catalyzed highly efficient aerobic oxidative synthesis of benzimidazoles direct from oximes in water
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This article presents a general and efficient method for aerobic oxidative synthesis of benzimidazoles from oximes catalyzed by Fe(NO3)3·9H2O under air in water. This practical method uses air as an economic and green oxidant, water as a green solvent, and tolerates a wide range of substrates that can afford the target benzimidazoles in moderate to good yields.
- Yu, Jiatao,Lu, Ming
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p. 471 - 479
(2016/04/26)
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- Catalytic Oxidative Coupling of Primary Amines under Air: A Flexible Route to Benzimidazole Derivatives
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Benzimidazoles are of fundamental importance in chemistry and biology, and the development of efficient, environmentally benign methods for their preparation remains a key challenge for organic chemists. In a biomimetic approach inspired by copper amine oxidases, we disclose herein the scope and factors influencing the success of the cooperative action of CuBr2 as electron-transfer mediator and a topaquinone-like substrate-selective catalyst in the oxidative cyclocondensation of primary amines with o-aminoanilines. This one-pot atom-economic multistep process, which works under green conditions with ambient air as the terminal oxidant, low loadings of catalyst, and equimolar amounts of commercially available amine substrates, is particularly suitable for the preparation of 1,2-disubstituted benzimidazoles. Furthermore, it allows the functionalization of nonactivated primary aliphatic amines, which are known to be challenging substrates for non-enzymatic catalytic aerobic systems.
- Nguyen, Khac Minh Huy,Largeron, Martine
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p. 1025 - 1032
(2016/03/01)
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- Electrochemical Synthesis of Benzazoles from Alcohols and o-Substituted Anilines with a Catalytic Amount of CoII Salt
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An electrochemical synthesis of benzazoles directly from alcohols and o-substituted anilines has been developed. The reaction conditions have been optimized by varying the composition of the electrolyte and the metal salt used as catalyst. The cyclization proceeds smoothly with a catalytic amount of a cobalt salt under air at room temperature to afford 2-substituted benzimidazoles, benzothiazoles, and benzoxazoles in good to excellent yields with a wide substrate scope.
- Lai, Yin-Long,Ye, Jian-Shan,Huang, Jing-Mei
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supporting information
p. 5425 - 5429
(2016/04/09)
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- An efficient route for the synthesis of benzimidazoles via a hydrogen-transfer strategy between o-nitroanilines and alcohols
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[1,1′-Bis(diphenylphosphino)ferrocene]dichloropalladium(II) has been used as an efficient catalyst for the synthesis of 2-substituted benzimidazoles via a hydrogen-transfer strategy. Various 2-substituted benzimidazoles were synthesized in good to excellent yields (up to 97%). The reaction shows good functional group tolerance. And no additional additive, oxidant, or reductant was required for the reaction.
- Li, Xiaotong,Hu, Renhe,Tong, Yao,Pan, Qiang,Miao, Dazhuang,Han, Shiqing
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supporting information
p. 4645 - 4649
(2016/09/23)
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