- AN EFFICIENT PREPARATION OF 4-ARYLMETHYLISOXAZOL-5-ONES BY SELECTIVE REDUCTION OF THE 4-ARYLMETHYLENEISOXAZOL-5-ONES
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An efficient selective reduction of the exocyclic double bond of the 4-arylmethyleneisoxazol-5-ones with o-phenylenediamines and aldehydes is described. 4-arylmethylisoxazol-5-ones are produced in high yields together with comparable quantities of benzimidazoles.
- Risitano, Francesco,Grassi, Giovanni,Foti, Francesco
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- 1-Methylimidazolium ionic liquid supported on Ni@zeolite-Y: fabrication and performance as a novel multi-functional nanocatalyst for one-pot synthesis of 2-aminothiazoles and 2-aryl benzimidazoles
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In the present study, 1-methyl-3-(3-trimethoxysilylpropyl)-1H-imidazol-3-ium chloride-supported Ni@zeolite-Y-based nanoporous materials (Ni@zeolite-Im-IL) were synthesized and their structures were confirmed using different characterization techniques such as FT-IR, FE-SEM, EDX, XRD, BET and TGA-DTG analyses. In order to synthesize this multi-functional nano-system, zeolite-NaY was modified first, with exchanged Ni2+ ions and 3-chloropropyltriethoxysilane (CPTES) as a coupling reagent and then functionalized to imidazolium chloride ionic liquid by N-methylimidazole. New multi-functional nano-material of Ni@zeolite-Im-IL demonstrated high activity in the catalytic synthesis of 2-aminothiazoles 3a–l by one-pot reaction of methylcarbonyls, thiourea and iodine at 80?°C in DMSO with good to excellent yields (85–98%). Also, the catalytic synthesis of 2-aryl benzimidazoles, 6a–m was performed by the condensational reaction of o-arylendiamine and aromatic aldehydes in EtOH at room temperature with excellent yields (90–98%). Advantages of this efficient synthetic strategy include higher purity and shorter reaction time, excellent yield, easy isolation of products, the good stability, activity and feasible reusability of the metallic ionic liquid nanocatalyst. These benefits have made this method more compatible with the principles of green chemistry. Graphical abstract: [Figure not available: see fulltext.]
- Kalhor, Mehdi,Zarnegar, Zohre
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p. 519 - 540
(2021/12/03)
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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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- 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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- Preparation method of 2-substituted benzimidazole compound
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The invention discloses a preparation method of a 2-substituted benzimidazole compound, and belongs to the field of synthesis of benzimidazole compounds. The 2-substituted benzimidazole compound is synthesized in an organic solvent by taking an o-nitroaniline compound, aromatic aldehyde, o-dinitrobenzene and aromatic aldehyde as raw materials and taking Co particles wrapped by a nitrogen-doped carbon material as a catalyst. According to the method, the 2-substituted benzimidazole compound can be prepared at room temperature, the reaction conditions are mild, the yield is as high as 95%, the selectivity is as high as 99%, and the method is economical, environmentally friendly and wide in substrate applicability. The used catalyst is easy to prepare, low in cost and good in reusability, canbe separated by utilizing magnetism, and is convenient to recover, so that the method has a relatively strong industrial application prospect.
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Paragraph 0079-0083
(2021/02/20)
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- Visible-Light Photoredox Catalyzed Double C-H Functionalization: Radical Cascade Cyclization of Ethers with Benzimidazole-Based Cyanamides
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A visible-light photoredox catalyzed radical cascade cyclization of simple ethers with cyanamides is developed at room temperature. This strategy involves sequential inert Csp3-H/Csp2-H functionalizations through intermolecular addition reaction of oxyalkyl radicals to N-cyano groups followed by radical cyclization of iminyl radicals in situ generated with C-2 aryl rings. This method allows for efficient synthesis of tetracyclic benzo[4,5]imidazo[1,2-c]quinazolines. Importantly, this is the first example of an intermolecular-intramolecular radical cascade cyclization reaction of cyanamides.
- Jiang, Si,Tian, Xiao-Jing,Feng, Shu-Yao,Li, Jiang-Sheng,Li, Zhi-Wei,Lu, Cui-Hong,Li, Chao-Jun,Liu, Wei-Dong
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supporting information
p. 692 - 696
(2021/02/01)
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- Cobalt ferrite magnetic nanoparticles as highly efficient catalyst for the mechanochemical synthesis of 2-aryl benzimidazoles
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A highly efficient magnetically separable nano cobalt ferrite catalyst was synthesized via the sol-gel auto combustion method, characterized by powder XRD, SEM, TEM, UV–Visible, FT-IR, magnetic study, and BET isotherm analysis. The synthesized material was found to be an efficient heterogeneous Lewis acid catalyst for the synthesis of 2-aryl benzimidazole derivatives via solvent-free mechanochemical synthesis. The notable features of this new protocol include solvent-free reaction, cost-effectiveness, good yields, and environmental friendliness to afford the products within a short reaction time along with easy recovery and reuse of the nano catalyst.
- Borade, Ravikumar M.,Jadhav, K. M.,Kale, Swati B.,Pawar, Rajendra P.,Tekale, Sunil U.
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- Preparation method 2 -substituted benzimidazole derivative
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The invention belongs to the field of fine chemical product production, and particularly relates to 2 -substituted benzimidazole derivative preparation method which comprises the following steps: (1) taking O-phenylenediamine and aldehyde as raw materials, carrying out catalytic condensation, cyclization and oxidation reaction in a eutectic solvent. (2) Water is added to the reaction system, the separated product is filtered, and the eutectic solvent is recycled. (3) After recrystallization, a target product is obtained. The method has the advantages of simple operation process, easily available raw materials, low cost, high purity of the target product and no catalyst participation, can effectively prevent isomer formation, and is beneficial to large-scale production.
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Paragraph 0083-0087
(2021/11/10)
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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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- 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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- 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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- Transition-Metal-Free Transfer Hydrogenative Cascade Reaction of Nitroarenes with Amines/Alcohols: Redox-Economical Access to Benzimidazoles
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This report describes an efficient transition-metal-free process toward the transfer hydrogenative cascade reaction between nitroarenes and amines or alcohols. The developed redox-economical approach was realized using a combination of KOtBu and Et3SiH as reagents, which allows the synthesis of benzimidazole derivatives via σ-bond metathesis. The reaction conditions hold well over a wide range of substrates embedded with diverse functional groups to deliver the desired products in good to excellent yields. The mechanistic proposal has been depicted on the basis of a series of control experiments, mass spectroscopic evidence which is well supported by density functional theory (DFT) calculations with a feasible energy profile.
- Gujjarappa, Raghuram,Kabi, Arup K.,Malakar, Chandi C.,Musib, Dulal,Roy, Anupam,Sahoo, Abhishek,Singh, Virender,Vodnala, Nagaraju
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p. 14597 - 14607
(2021/11/12)
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- A one-step synthesis of substituted benzo- and pyridine-fused 1H-imidazoles
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Substituted benzimidazoles and pyrimidazoles are an important group of heterocyclic aromatic organic compounds in the field of medicinal chemistry. A one-step microwave accelerated synthesis of substituted benzo- and pyridine-fused 1H-imidazoles has been described. Mechanistically, the reaction proceeds by reacting substituted 2-fluoronitrobenzene and substituted arylamine through the formation of N-hydroxy intermediate, which at higher temperature cleaves to afford the desired product. This approach achieved reductions in reaction times, higher yields, cleaner reactions than the previously described synthetic processes.
- Bhatt, Ashish,Kant, Ravi,Kumar, Sonu,Reddy, Yella,Sarmah, Manash P.
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- H2 Activation with Co Nanoparticles Encapsulated in N-Doped Carbon Nanotubes for Green Synthesis of Benzimidazoles
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Co nanoparticles (NPs) encapsulated in N-doped carbon nanotubes (Co@NC900) are systematically investigated as a potential alternative to precious Pt-group catalysts for hydrogenative heterocyclization reactions. Co@NC900 can efficiently catalyze hydrogenative coupling of 2-nitroaniline to benzaldehyde for synthesis of 2-phenyl-1H-benzo[d]imidazole with >99 % yield at ambient temperature in one step. The robust Co@NC900 catalyst can be easily recovered by an external magnetic field after the reaction and readily recycled for at least six times without any evident decrease in activity. Kinetic experiments indicate that Co@NC900-promoted hydrogenation is the rate-determining step with a total apparent activation energy of 41±1 kJ mol?1. Theoretical investigations further reveal that Co@NC900 can activate both H2 and the nitro group of 2-nitroaniline. The observed energy barrier for H2 dissociation is only 2.70 eV in the rate-determining step, owing to the presence of confined Co NPs in Co@NC900. Potential industrial application of the earth-abundant and non-noble transition metal catalysts is also explored for green and efficient synthesis of heterocyclic compounds.
- Lin, Chuncheng,Wan, Weihao,Wei, Xueting,Chen, Jinzhu
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p. 709 - 720
(2020/11/30)
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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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- 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; 0188; 0189
(2020/02/20)
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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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- 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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- Transforming Oxadiazolines through Nitrene Intermediates by Energy Transfer Catalysis: Access to Sulfoximines and Benzimidazoles
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Subtle differences in reaction conditions facilitated unprecedented photocatalytic reactions of oxadiazolines by energy transfer catalysis. A set of compounds, sulfoximines and benzimidazoles, were ingeniously prepared from oxadiazolines via nitrene intermediates by photocatalytic N-O/C-N bond cleavages. The synthesis of sulfoximines was realized through intermolecular N-S bond formation between nitrene intermediates and sulfoxides, whereas benzimidazoles were obtained via intramolecular aromatic substitution of the nitrene to the tethered aryl substituent.
- Park, Do Dam,Min, Kwan Hong,Kang, Jihee,Hwang, Ho Seong,Soni, Vineet Kumar,Cho, Cheon-Gyu,Cho, Eun Jin
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p. 1130 - 1134
(2020/02/15)
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- Copper-Mediated Diamination of Arylboronic Acids for the Synthesis of 2-Aryl Benzimidazoles Using Trimethylsilyl Azide as the Amino Sources with Aldehydes
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A direct and versatile copper-mediated three-component reaction of arylboronic acids, trimethylsilyl azide and aldehydes for the synthesis of benzimidazoles is reported. The reaction is well tolerated by a wide range of substituted aromatic aldehydes and aromatic boronic acids to produce the corresponding benzimidazoles in moderate to high yields. Mechanism investigations demonstrated that copper-promoted Chan-Evans-Lam coupling, C?H amination, and oxidative cycloaddition are involved in the tandem processes. (Figure presented.).
- Xie, Zeqiang,Zhou, Fengtao,Ding, Ke
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supporting information
p. 3442 - 3446
(2020/07/30)
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- Solvent-Free N-Alkylation and Dehydrogenative Coupling Catalyzed by a Highly Active Pincer-Nickel Complex
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The synthesis and characterization of a pincer-nickel complex of the type (iPr2NNN)NiCl2(CH3CN) is reported here. We have demonstrated the utility of this pincer-nickel complex (0.02 and 0.002 mol %) for the catalytic N-alkylation of amines using various alcohols. Under solvent-free conditions, while the highest yield (ca. 90%) was obtained for the alkylation of 2-aminopyridine with naphthyl-1-methanol, excellent turnovers (34000 TONs) were observed for the alkylation of 2-aminopyridine with 4-methoxybenzyl alcohol. To demonstrate the synthetic utility of these systems, high-yield reactions (up to 98%) have been probed for representative substrates with a higher loading of the pincer-nickel catalyst (4 mol %). DFT studies indicate that while β-hydride elimination is the RDS for alcohol dehydrogenation, the N-alkylated product can be formed either via hydrogenation with a rate-determining σ-bond metathesis or by alcoholysis that has imine insertion as the RDS. All of the corresponding resting states have been observed by HRMS (ESI) analysis. The labeling experiments are also complementary to DFT studies and show evidence for the involvement of the benzylic C-H bond in the RDS with a kCHH/kCHD value of about 2.5. This method has been applied to accomplish efficient (2000 TONs) dehydrogenative coupling leading to various benzimidazoles.
- Arora, Vinay,Dutta, Moumita,Das, Kanu,Das, Babulal,Srivastava, Hemant Kumar,Srivastava, Hemant Kumar,Kumar, Akshai,Kumar, Akshai
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p. 2162 - 2176
(2020/06/05)
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- Oxidative Cyclization Approach to Benzimidazole Libraries
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An efficient approach to the parallel synthesis of benzimidazoles from anilines is described. Library approaches to vary the N1 and C2 vectors of benzimidazoles are well established; however, C4-C7 variation has traditionally relied on 1,2-dianiline build
- Arnold, Eric P.,Mondal, Prolay K.,Schmitt, Daniel C.
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supporting information
p. 1 - 5
(2020/02/20)
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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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- 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; 0047
(2019/01/21)
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- Synthesis of 2-substituted benzothiazoles via the Br?nsted acid catalyzed cyclization of 2-amino thiophenols with nitriles
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A convenient and efficient method for the synthesis of 2-substituted benzothiazoles from simple and readily available 2-amino thiophenols and nitriles is described. The Br?nsted acid-catalyzed cyclization reaction was performed under metal and solvent-free conditions.
- Yu, Xiaoqiang,Yin, Qing,Zhang, Zhiheng,Huang, Tianyu,Pu, Zichao,Bao, Ming
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p. 1964 - 1966
(2019/06/27)
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- A novel ternary GO@SiO2-HPW nanocomposite as an efficient heterogeneous catalyst for the synthesis of benzazoles in aqueous media
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A new solid acid catalyst, consisting of 12-phosphotungstic heteropoly acid (HPW) supported on graphene oxide/silica nanocomposite (GO@SiO2), has been developed via immobilizing HPW onto an amine-functionalized GO/SiO2 surface through coordination interaction (GO@SiO2-HPW). The GO@SiO2-HPW nanocomposite was characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and powder X-ray diffraction (XRD). The prepared nanocomposite could be dispersed homogeneously in water and further used as a heterogeneous, reusable, and efficient catalyst for the synthesis of benzimidazoles and benzothiazoles by the reaction of 1,2-phenelynediamine or 2-aminothiophenol with different aldehydes.
- Habibzadeh, Setareh,Firouzzadeh Pasha, Ghasem,Tajbakhsh, Mahmood,Amiri Andi, Nasim,Alaee, Ehsan
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p. 934 - 944
(2019/06/13)
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- 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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- Synthesis of new TCH/Ni-based nanocomposite supported on SBA-15 and its catalytic application for preparation of benzimidazole and perimidine derivatives
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A stable nickel-decorated SBA-15 nanocomposite (Ni/TCH@SBA-15) was synthesized through surface modification of silica nanoparticles with 3-chloropropyltriethoxysilane (CPTES) and thiocarbohydrazide (TCH) followed by metal–ligand coordination with Ni (II). The structure of this organometallic nanocomposite was characterized by Fourier transform-infrared, field emission-scanning electron microscopy, EDAX, transmission electron microscopy, atomic absorption spectroscopy and N2 adsorption–desorption (Brunauer–Emmett–Teller) techniques. The catalytic performance of Ni/TCH@SBA-15 (NNTS-15) was determined for the synthesis of 2-aryl-substituted benzimidazoles and 2,3-dihydroperimidines. The excellent yields within shorter reaction times, simplicity of catalytic methods, non-toxicity and clean reactions, mild reaction conditions and easy work-up procedure are the important merits of these synthetic protocols. Moreover, the Ni (II) bonded to the SBA-15 surface was stable under the catalytic reaction conditions resulting in its efficient recycling and reuse.
- Kalhor, Mehdi,Rezaee-Baroonaghi, Fahimeh,Dadras, Akbar,Zarnegar, Zohre
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- 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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- 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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- 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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- Additive- and Oxidant-Free Expedient Synthesis of Benzimidazoles Catalyzed by Cobalt Nanocomposites on N-Doped Carbon
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A one-pot direct synthesis of a wide range of biologically active benzimidazoles through coupling of phenylenediamines and aldehydes catalyzed by a highly recyclable nonnoble cobalt nanocomposite was developed. A broad set of benzimidazoles can be efficiently synthesized in high yields and with good functional-group tolerance under additive- and oxidant-free mild conditions. The catalyst can be easily recycled for successive uses, and the process permits gram-scale syntheses of benzimidazoles.
- Wang, Zhaozhan,Song, Tao,Yang, Yong
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supporting information
p. 319 - 324
(2019/02/12)
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- Sulfur-Catalyzed Oxidative Coupling of Dibenzyl Disulfides with Amines: Access to Thioamides and Aza Heterocycles
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In the presence of catalytic amounts of elemental sulfur, dibenzyl disulfide/DMSO was found to be an excellent thiobenzoylating agent of amines to provide a wide range of thioamides. The reaction becomes autocatalytic when anilines substituted by an o-cyclizable group were used as nucleophile, leading to the corresponding 2-aryl aza heterocycles. (Figure presented.).
- Nguyen, Thanh Binh,Nguyen, Le Phuong Anh,Nguyen, Thi Thu Tram
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supporting information
p. 1787 - 1791
(2019/02/26)
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- Transcriptome analysis predicts mode of action of benzimidazole molecules against Staphylococcus aureus UAMS-1
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Antimicrobial drug resistance is one of the most critical problems that plagued the human race in modern times. Discovery of novel antibiotics is important to counter this threat. Accordingly, herein we have reported the discovery of substituted benzimidazole class of molecules with antimicrobial property (specifically against Staphylococcus aureus). They were initially identified through a random screening and a novel catalytic synthetic strategy was utilized to access them. in vitro screening and phenotypic profiling revealed the antimicrobial nature. De novo transcriptome and gene analyses predicted the putative targets. This work provides a solid foundation for developing the benzimidazoles as a target specific antimicrobial preclinical candidate.
- Chauhan, Deepika,Hati, Santanu,Priyadarshini, Richa,Sen, Subhabrata
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p. 490 - 503
(2019/06/20)
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- Method for preparing benzimidazole and quinazoline compounds by adopting supported nickel catalyst (by machine translation)
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The invention discloses a method for synthesizing benzimidazole and quinazoline compounds by oxidative coupling and dehydrogenation of a nitrogen-doped hierarchical porous biomass-based carbon material supported catalyst and a preparation method. The method comprises the following steps: adding o-phenylenediamine compound, alcohol, supported catalyst, toluene and potassium tert-butoxide as a solvent, carrying out reaction under 50~150 °C conditions, carrying out reaction 4~24 hours, cooling to room temperature, filtering the reaction liquid, and obtaining a benzimidazole compound or quinazoline compound. The method adopts "one-pot method" preparation, the intermediate can be separated and purified, energy consumption can be reduced, and the efficiency. (by machine translation)
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Paragraph 0054-0056; 0057; 0059
(2019/07/16)
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- SYNTHESIS METHOD OF IMIDAZOLES
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PROBLEM TO BE SOLVED: To provide benzimidazoles with small number of processes at high selectivity and high purity. SOLUTION: A synthesis method of benzimidazoles synthesizes at least one of an imidazole derivative and a carboxy imidazole derivative by reacting a diamine derivative and at least one of a dicarboxylic acid derivative and a dicarboxylic acid anhydride derivative in subcritical water or in supercritical water. For example, in subcritical water or in supercritical water, by reacting o-phenylene diamine and at least one of phthalic acid and phthalic anhydride, 2-phenylbenzimidazole and 2-o-benzimidazole benzoate are synthesized. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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Paragraph 0112; 0113
(2019/05/15)
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- Bimetallic Cu-Mn B spinel oxide catalyzed oxidative synthesis of 1,2-disubstituted benzimidazoles from benzyl bromides
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Cu-Mn B (a heterogeneous catalyst) catalyzed synthesis of 1-benzyl-2-phenyl-1H-benzo[d]imidazoles is reported. In this reaction, 2-phenyl-1H-benzo[d]imidazoles are found to be the side products. The reported protocol is simple and highly efficient, tolerates a wide variety of substrates and the products were formed in good to excellent yield.
- Sharma, Rohit,Sofi, Firdoos Ahmad,Rana, Preeti,Bharatam, Prasad V.
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supporting information
p. 4013 - 4016
(2019/03/08)
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- Cooperative iridium complex-catalyzed synthesis of quinoxalines, benzimidazoles and quinazolines in water
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Herein, an efficient methodology for the synthesis of a diverse class of N-heterocyclic moieties, such as quinoxalines, benzimidazoles and quinazolines, was developed in water using bio-renewable alcohols. The quinoxalines were successfully synthesized from a wide range of diamines and nitroamines with diols in air. Interestingly, benzimidazoles and quinazolines were synthesized with excellent isolated yields without using any external base. Finally, the preparative scale synthesis of various N-heterocycles and pharmaceutically active quinoxalines established the practicability of this protocol. For this iridium system, a metal-ligand cooperative mechanism was proposed based on kinetic and DFT studies.
- Chakrabarti, Kaushik,Maji, Milan,Kundu, Sabuj
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supporting information
p. 1999 - 2004
(2019/04/27)
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- A Tandem Aerobic Photocatalytic Synthesis of Benzimidazoles by Cobalt Ascorbic Acid Complex Coated on TiO2 Nanoparticles Under Visible Light
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Abstract: In this study, we developed methods for the one pot environmentally benign synthesis of benzimidazoles by cobalt ascorbic acid complex coated on TiO2 nanoparticles via aerobic photooxidative cyclization reactions. Easy work-up procedure, reusability of the catalyst and scalable to the multi-mole scale, which is valuable for an industrial process make these catalytic systems highly attractive. Also, the combination of photocatalytic and catalytic reactions presented here may help to develop a new strategy towards the development of photocatalysis-based organic synthesis. Graphical Abstract: [Figure not available: see fulltext.].
- Feizpour, Fahimeh,Jafarpour, Maasoumeh,Rezaeifard, Abdolreza
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- Inexpensive weight-reducing aid (L-carnitine) as an efficient catalyst for synthesis of benzimidazoles
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Aim and Objective: The benzimidazole derivatives have been obtained via weight-reducing aid (L-Carnitine) as a cheap catalyst. A wide range of aromatic aldehydes easily undergo condensations with substituted o-phenylendiamine under mild condition to affor
- Zhang, Min,Huang, Guoling,Zhang, Xuefang,Lin, Zhenyuan,Li, Yibiao,Li, Bin,Chen, Lu
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p. 567 - 570
(2019/01/14)
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- Biomass-Derived N-doped Carbon Materials with Silica-Supported Ultrasmall ZnO Nanoparticles: Robust Catalysts for the Green Synthesis of Benzimidazoles
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Ultrasmall ZnO nanoparticles anchored on N-doped carbon materials with a silica support (ZnO/SiO2-NC) were fabricated from chitosan and metal ions by using a one-pot self-assembly strategy and were successfully applied to the synthesis of 2-arylbenzimidazoles under mild conditions. These catalysts showed excellent stability and could be used six times without any loss of conversion and selectivity. The use of silica gel and the biomass chitosan as a source of hydrophilic N-doped carbon materials facilitated the uniform dispersion of the ZnO nanoparticles in methanol and therefore the contact of these nanoparticles with reactants, thus contributing to a high catalytic performance. TEM analysis showed that the ZnO nanoparticles were around 2.55 nm in diameter and uniformly distributed on the support surface. The binding behavior of ZnO and N-doped carbon materials affected the catalytic activity. Interestingly, temperature-programmed NH3 desorption indicated that the interactions between ZnO and N-doped carbon materials might induce the presence of more acidic sites in these catalysts, thus resulting in enhanced activity and hence promoting this transformation.
- Chen, Bo,Zhang, Chan,Niu, Libo,Shi, Xiaozhen,Zhang, Huiling,Lan, Xingwang,Bai, Guoyi
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p. 3481 - 3487
(2018/03/21)
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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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- Zn3(BTC)2 as a Highly Efficient Reusable Catalyst for the Synthesis of 2-Aryl-1H-Benzimidazole
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Zn3(BTC)2 metal-organic frameworks as recyclable and heterogeneous catalysts were effectively used to catalyze the synthesis of benzimidazole derivatives from o-phenylendiamine and aldehydes in ethanol. This method provides 2-aryl-1H
- Sajjadifar, Sami,Arzehgar, Zeinab,Ghayuri, Azadeh
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p. 205 - 211
(2017/11/13)
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- Mesoporous silica supported ytterbium as catalyst for synthesis of 1,2-disubstituted benzimidazoles and 2-substituted benzimidazoles
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The benzimidazole ring is an important pharmacophore in contemporary drug discovery. Thus, effort to identifying new compounds containing benzimidazole scaffolds have gained much attention in recent years. In the present study, MCM-41 type mesoporous silica with large pore (l-MSN) supported ytterbium was successfully prepared by wet impregnation method. Among rare earth metal salts, ytterbium triflate has already been widely investigated as a catalyst in organic synthesis but less toxic ytterbium oxide has yet to be explored. Relatively high abundance and low cost of ytterbium with respect to many catalytically active metals (e.g. Pd, Au, Ru, Ir, Pt) offer an opportunity to develop sustainable catalysts for organic conversions. The catalyst has been characterized by various techniques including nitrogen adsorption, FT-IR, TEM, SEM, EDX technique and elemental mapping. The obtained materials exhibit high surface area and a narrow distribution of mesoporosity. The catalytic performance of the Yb@l–MSNs was tested by synthesis of 1,2-disubstituted benzimidazoles and 2-substituted benzimidazoles through the coupling of aldehydes with o-phenylenediamine. The catalyst resulted in excellent yields in short reaction times and the reaction showed tolerance toward both electron-donating and electron-withdrawing functional groups at room temperature. A particularly interesting finding was the solvent selectivity of this reaction; namely, 1,2-disubstituted benzimidazoles generated as major product in water-ethanol, while the 2-substituted benzimidazoles was generated exclusively in non-polar solvents like toluene.
- Samanta, Partha Kumar,Banerjee, Rumeli,Richards, Ryan M.,Biswas, Papu
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- A metal-organic framework based multifunctional catalytic platform for organic transformation and environmental remediation
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Given the need for an efficient reaction platform, a multifunctional material has been developed through the integration of iodine into a Cd2+ based MOF as a new catalytic system for organic transformation. Furthermore, the Cd-MOF itself has been successfully used as a potential material for photocatalytic dye degradation. The iodine incorporated MOF showed tremendous efficiency in organic catalysis for the synthesis of a library of benzimidazole derivatives with yield >80%. In addition, the same iodine loaded MOF (I2@Cd-MOF) exhibits good applicability and reusability for the synthesis of thienyldipyrromethane. Apart from this, the photocatalytic activity of the Cd-MOF was also evaluated under visible light irradiation which revealed excellent photocatalytic activity (82%) for MB degradation without the use of any enhancers. Altogether, this catalytic platform established its efficacy as a multifunctional catalyst in the organic synthesis of biologically active motifs and photocatalytic dye degradation.
- Kaur, Harpreet,Venkateswarulu,Kumar, Suneel,Krishnan, Venkata,Koner, Rik Rani
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p. 1488 - 1497
(2018/02/09)
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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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- Metal-free synthesis of N-containing heterocycles from O-substituted aniline derivatives via 2,4,6-trihydroxybenzoic acid-catalyzed oxidative dehydrogenation of benzylamines under oxygen atmosphere
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A series of N-heterocycles, i.e., benzimidazoles, benzoxazoles, and benzothiazoles, can be conveniently synthesized by the oxidative cyclization of benzylamines with o-substituted aniline derivatives, i.e., o-phenylenediamines, o-aminophenols, and o-aminothiophenols, using 2,4,6-trihydroxybenzoic acid as an organocatalyst under an oxygen atmosphere. This approach provides a mild and efficient tool towards benzimidazoles and benzothiazoles with good yields and a broad substrate scope. The developed synthesis of N-heterocycles might proceed via the oxidative dehydrogenation of benzylamines (ArCH2NH2), generating the corresponding imines (ArCH=NH) as key intermediates.
- Kumazawa, Shun,Uematsu, Akinori,Dong, Chun-Ping,Kodama, Shintaro,Nomoto, Akihiro,Ueshima, Michio,Ogawa, Akiya
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p. 842 - 853
(2019/04/26)
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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; 0048
(2018/11/27)
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