- Sulfonic-acid-functionalized activated carbon made from tea leaves as green catalyst for synthesis of 2-substituted benzimidazole and benzothiazole
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Abstract: A simple and efficient procedure for synthesis of 2-substituted benzimidazole and benzothiazole has been developed by using sulfonic-acid-functionalized activated carbon as heterogeneous catalyst. The activated material was prepared from matured tea leaf in presence of phosphoric acid as activating agent. The final catalyst was prepared by anchoring –SO3H group on the surface of the activated carbon. The catalyst could be easily recovered and reused for more than three catalytic cycles without significant loss in catalytic activity. The catalytic performance of the catalyst was found to be superior to that of a similar catalyst prepared from montmorillonite K10. Graphical Abstract: [Figure not available: see fulltext.].
- Goswami, Mridusmita,Dutta, Mintu Maan,Phukan, Prodeep
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- New one-pot procedure for the synthesis of 2-substituted benzimidazoles
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A highly selective synthesis of 2-substituted benzimidazole derivatives from the reaction of o-phenylendiamine derivatives and aromatic aldehydes in the presence of an organic salt, NH4OAc, in absolute ethanol is presented. The products were obtained by evaporating the solvent followed by a simple recrystallization with excellent yields. Copyright Taylor & Francis Group, LLC.
- Sharghi, Hashem,Asemani, Omid,Khalifeh, Reza
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- Synthesis of 2-Substituted benzimidazoles catalyzed by FeCl 3/Al2O3 under ultrasonic irradiation
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2-substituted benzimidazoles have been synthesized in a single pot from aromatic aldehydes and ophenylenediamine catalyzed by FeCl3/Al 2O3 in DMF under ultrasonic irradiation and afforded good yields in a short period of t
- Chen, Guo-Feng,Dong, Xiao-Yun,Meng, Fan-Zhu,Chen, Bao-Hua,Li, Ji-Tai,Wang, Shu-Xiang,Bai, Guo-Yi
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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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- Reusable nano-zirconia-catalyzed synthesis of benzimidazoles and their antibacterial and antifungal activities
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In this article, a zirconia-based nano-catalyst (Nano-ZrO2 ), with intermolecular C-N bond formation for the synthesis of various benzimidazole-fused heterocycles in a concise method is reported. The robustness of this reaction is demonstrated
- Ahmad, Naushad,Ahmed, Faheem,Albalawi, Fadwa,Alomar, Suliman Yousef,Basaveswara Rao, M. V.,Cheedarala, Ravi Kumar,Naidu, Tentu Manohra,Rao, Nalla Krishna,Rao, Tentu Nageswara,Reddy, G. Rajasekhar
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- A novel ionic liquid based on imidazolium cation as an efficient and reusable catalyst for the one-pot synthesis of benzoxazoles, benzthiazoles, benzimidazoles and 2-arylsubstituted benzimidazoles
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A novel dicationic ionic liquid based on imidazolium cation is designed, synthesized and successfully used as catalyst for the one-pot synthesis of benzoxazoles, benzthiazoles, benzimidazoles and 2-arylsubstituted benzimidazoles. The remarkable feature of this new catalyst is its ethyleneoxy bridge which participates in dissolving organic compound in ionic liquid. The application of this ionic liquid is studied in a new one-pot method for synthesis of heterocyclic compounds under solvent-free conditions. Simple and convenient procedure, high conversion, reusability of catalyst, easy purification and shorter reaction time are the advantageous features of this method.
- Hasanpour, Maede,Eshghi, Hossein,Bakavoli, Mehdi,Mirzaeia, Mahdi
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- 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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- Magnetically separable MnFe2O4 nano-material: An efficient and reusable heterogeneous catalyst for the synthesis of 2-substituted benzimidazoles and the extended synthesis of quinoxalines at room temperature under aerobic conditions
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A simple and efficient protocol has been developed for the synthesis of biologically relevant 2-substituted benzimidazoles and quinoxalines using magnetically separable manganese ferrite (MnFe2O4) nanopowder for the first time as a reusable heterogeneous catalyst at room temperature under aerobic conditions. MnFe2O4 nanoparticles were prepared by a simple sol-gel method using starch as a bio-polymeric matrix, and characterized by XRD, TEM, EDAX and VSM analyses. The Royal Society of Chemistry 2013.
- Brahmachari, Goutam,Laskar, Sujay,Barik, Puspendu
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- Green synthesis of privileged benzimidazole scaffolds using active deep eutectic solvent
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The exploitation and use of alternative synthetic methods, in the face of classical procedures that do not conform to the ethics of green chemistry, represent an ever-present problem in the pharmaceutical industry. The procedures for the synthesis of benzimidazoles have become a focus in synthetic organic chemistry, as they are building blocks of strong interest for the development of compounds with pharmacological activity. Various benzimidazole derivatives exhibit important activities such as antimicrobial, antiviral, anti-inflammatory, and analgesic activities, and some of the already synthesized compounds have found very strong applications in medicine praxis. Here we report a selective and sustainable method for the synthesis of 1,2-disubstituted or 2-substituted benzimidazoles, starting from o-phenylenediamine in the presence of different aldehydes. The use of deep eutectic solvent (DES), both as reaction medium and reagent without any external solvent, provides advantages in terms of yields as well as in the work up procedure of the reaction.
- Gioia, Maria Luisa Di,Cassano, Roberta,Costanzo, Paola,Cano, Natividad Herrera,Maiuolo, Loredana,Nardi, Monica,Nicoletta, Fiore Pasquale,Oliverio, Manuela,Procopio, Antonio
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- A nanoscopic icosahedral {Mo72Fe30} cluster catalyzes the aerobic synthesis of benzimidazoles
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In this study, the catalytic efficiency of amorphous {Mo72Fe30} nanocapsules as a safe Keplerate polyoxometalate in organic synthesis was exploited. The easy-made solid catalyst exhibited high efficiency using a very low dosage (0.02
- Garazhian, Zohreh,Rezaeifard, Abdolreza,Jafarpour, Maasoumeh
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- Mild, one-pot preparation of 2-substituted benzimidazoles from organic halides
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Alkyl halides are feasibly transformed into benzimidazoles by a domino reaction under solvent-free conditions. The organic halides react with o-phenylenediamines in stoichiometric amounts in the presence of pyridine-N-oxide to produce the desired substituted benzimidazoles. This domino synthesis does not require catalysts. The synthesis occurs in dry medium and the environmental impact is minimal. The method provides products without intermediate separation. A mechanism of benzimidazole synthesis is also proposed.
- Br?tulescu, George
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- One-pot, green approach synthesis of 2-aryl substituted benzimidazole derivatives catalyzed by water extract of papaya bark ash
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A simple, green, rapid and environmentally benign route has been developed for the synthesis of 2-substituted benzimidazoles by the reaction of substituted o-phenylenediamine with different substituted benzoyl chloride using water extract of papaya bark ash (WEPBA) as a green catalyst at room temperature. This method provides several added advantages of being completely green, economic, giving high yields and minimizing use of hazardous solvents. Further, the separated product does not required any kind of chromatographic purification.
- Kantharaju,Hiremath, Prashant B.
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- One-pot synthesis of 1 H-benzimidazole derivatives using thiamine hydrochloride as a reusable organocatalyst
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A simple and efficient one-pot synthesis of 1H-benzimidazole derivatives using thiamine hydrochloride (VB1) as the organocatalyst from o-phenylenediamine and aldehyde in dimethylformamide is described. Compared to classical reaction conditions, this new method consistently has the advantages of excellent yields, metal-ion-free procedure, and good recovery and reusablity of catalyst.
- Lei, Min,Ma, Lei,Hu, Lihong
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- 1,3,5-Trimethylpyrazolium chloride based ionogel as an efficient and reusable heterogeneous catalyst for the synthesis of benzimidazoles
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A new approach for the synthesis of benzimidazoles using ionogel under solvent-free conditions is reported. Catalytic activity of ionogel was compared with silica coated with ionic liquid (silica-IL) and it was found that ionogel is highly active compared to silica-IL for the synthesis of benzimidazoles. Moreover, ionogel was recyclable for the synthesis of benzimidazoles. [Figure not available: see fulltext.]
- Sharma, Pankaj,Gupta, Monika
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- Simple and efficient method for the synthesis of benzimidazole derivatives using monoammonium salt of 12-tungstophosphoric acid
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Benzimidazoles have been synthesized in very good yield from o-phenylenediamine and aromatic aldehydes in the presence of monoammonium salt of 12-tungstophosphoric acid [(NH4)H2PW12O40], an efficient heterogeneous catalyst. This catalyst has the advantage
- Giri,Devi, B. L. A. Prabavathi,Gangadhar,Lakshmi, K. Vijaya,Prasad,Lingaiah,Prasad, P. S. Sai
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- Mesoporous molecular sieve MCM-41 as a novel and efficient catalyst to synthesis of 2-substituted benzimidazoles
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o-Phenylenediamine derivatives readily react with benzoyl chloride derivatives in the presence of MCM-41 as catalyst to yield 2-substituted benzimidazoles in very good yields.
- Heravi, Majid M.,Baghernejad, Bita,Oskooie, Hossein A.,Malakooti
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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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- Catalytic activity of Co(II) Salen&at;KCC-1 on the synthesis of 2,4,5-triphenyl-1H-imidazoles and benzimidazoles
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The synthesis, reactions and biological properties of imidazoles and benzimidazole make up the bulk of the ring chemistry. In this study, the reaction between different types of aromatic aldehydes and ammonium acetate with diphenylethanedione, in ethanol solvent, using the Co(II) Salen complex&at;KCC-1 catalyst which is produced from Co (II) complex which is supported onto the KCC-1 was studied. The results showed that the products were synthesized in good to excellent yields. The products were identified with IR and NMR spectroscopy. Also, the catalyst was identified by FT-IR, TGA, TEM, and XRD. Finally, the catalyst was reused several times without lack of catalytic activity.
- Ali Nasseri, Mohammad,Allahresani, Ali,Naghdi, Elaheh
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- Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)3 catalyst in the reaction selectivity
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An improved and greener protocol for the synthesis of benzimidazole derivatives, starting from o-phenylenediamine, with different aldehydes is reported. Double-condensation products were selectively obtained when Er(OTf)3 was used as the catalyst in the presence of electron-rich aldehydes. Conversely, the formation of mono-condensation products was the preferred path in absence of this catalyst. One of the major advantages of these reactions was the formation of a single product, avoiding extensive isolation and purification of products, which is frequently associated with these reactions. Theoretical calculations helped to understand the different reactivity established for these reactions. Thus, we found that the charge density on the oxygen of the carbonyl group has a significant impact on the reaction pathway. For instance, electron-rich aldehydes better coordinate to the catalyst, which favours the addition of the amine group to the carbonyl group, therefore facilitating the formation of double-condensation products. Reactions with aliphatic or aromatic aldehydes were possible, without using organic solvents and in a one-pot procedure with short reaction time (2-5 min), affording single products in excellent yields (75-99%). This convenient and eco-friendly methodology offers numerous benefits with respect to other protocols reported for similar compounds.
- Herrera Cano, Natividad,Uranga, Jorge G.,Nardi, Mónica,Procopio, Antonio,Wunderlin, Daniel A.,Santiago, Ana N.
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- Green synthesis of benzimidazole derivatives catalyzed by ionic liquid under microwave irradiation
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An efficient synthesis of benzimidazole derivatives from o-phenylene diamine and substituted aromatic aldehyde catalyzed by ionic liquid under microwave irradiation was reported. The synthesis conditions were first optimized by single factor experiments. Then, a central composite design combined with response surface methodology was used to study the most effective factors. Optimal conditions were synthesis time 1 h, the reactant/catalyst molar ratio 1:1:0.200, the temperature 50 °C and the microwave power 500 W. Under optimized conditions, the yields of benzimidazole derivatives were 78.55-97.66 %. This method offered the outstanding advantages, such as faster reaction rate, higher yields, recyclable catalyst, environmental friendliness, and simple workup procedure.
- Qin, Mingcong,Fu, Yujie,Wang, Xiqing,Zhang, Yuhang,Ma, Weidong
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- A simple, mild, and efficient procedure for high-yield synthesis of benzimidazoles using coppertriflate as catalyst
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(Chemical Equation Presented) Copper triflate has been found to be an efficient catalyst for the synthesis of benzimidazoles from ophenylenediamine and aldehydes at reflux temperature under acetonitrile solvent. This new method consistently has the advant
- Adharvana Chari,Sadanandam,Shobha,Mukkantib
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- Nanoporous aluminosilicate catalyst with 3D cage-type porous structure as an efficient catalyst for the synthesis of benzimidazole derivatives
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Herein we demonstrate for the first time, the synthesis of benzimidazoles through the coupling of aldehydes with o-phenylenediamine by using highly acidic nanoporous aluminosilicate with 3D structure and cage-type pores as the catalyst. The catalyst resulted in excellent yields in short reaction times presumably due to its high acidity, large pore diameter, high surface area, and cage-type 3D porous structure.
- Chari, Murugulla A.,Shobha,Kenawy, El-Refaie,Al-Deyab, Salem S.,Reddy, B.V. Subba,Vinu, Ajayan
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- MIL-101(Fe) hexagonal microspindle as a highly efficient, reusable and versatile catalyst for benzo-fused heterocyclic nucleus synthesis
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A highly reusable, efficient and versatile MIL-101(Fe) catalyst was prepared and characterized using various techniques including Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. This heterogeneous catalyst demonstrated a promising activity for condensation/cyclization reactions of various aryl aldehydes with 1,2-phenylenediamine or 2-aminothiophenol. The corresponding benzo-fused heterocyclic products were generated in good to excellent yields under mild conditions in the presence of the catalyst. In addition, the catalyst can be easily separated and reused in eight consecutive runs with consistent catalytic activity.
- Karimian, Ramin,Davarpanah, Seyed Javad
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- Copper-catalyzed C(sp2)-H amidation with azides as amino sources
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A copper-catalyzed C-H amidation process, with azides as amino sources under oxidant-free conditions, has been developed. When N-heterocycles were employed as directing groups, sulfonylazide and benzoylazide could be used as amidating reagents to provide corresponding N-arylamides. When amidines or imine were used, tandem C-N/N-N bond formation occurred to afford indazole derivatives in one pot.
- Peng, Jiangling,Xie, Zeqiang,Chen, Ming,Wang, Jian,Zhu, Qiang
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- Synthesis of 2-arylbenzimidazoles in water
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A simple and efficient procedure for the synthesis of 2-arylbenzimidazoles through a one-pot condensation of o-phenylenediamines with aryl aldehydes in water is described. Short reaction time, large-scale synthesis, easy and quick isolation of the product
- Panda, Siva S.,Jain, Subhash C.
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- Nickel-catalysed dehydrogenative coupling of aromatic diamines with alcohols: Selective synthesis of substituted benzimidazoles and quinoxalines
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The first nickel-catalysed dehydrogenative coupling of primary alcohols and ethylene glycol with aromatic diamines for selective synthesis of mono- and di-substituted benzimidazoles and quinoxalines is reported. The earth-abundant, non-precious and simple NiCl2/L1 system enables the synthesis of N-heterocycles releasing water and hydrogen gas as byproducts. Mechanistic studies involving deuterium labeling experiments and quantitative determination of hydrogen gas evaluation were performed.
- Bera, Atanu,Sk, Motahar,Singh, Khushboo,Banerjee, Debasis
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- Synthesis of graphene oxide supported copper–cobalt ferrite material functionalized by arginine amino acid as a new high–performance catalyst
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A novel Cu0.5Co0.5Fe2O4@Arg–GO catalytic system was successfully prepared by immobilization of copper substituted cobalt ferrite nanoparticles on arginine–grafted graphene oxide nanosheets, in which ferrite moiety acts as an oxidation catalyst and arginine has the role of base catalyst. Also, arginine amino acid was used to modify the surface of graphene oxide nanosheets which the prepared support can improve dispersion and uniform loading of nanoparticles. The prepared nanocomposite was characterized by flame atomic absorption spectroscopy (FAAS), inductively coupled plasma optical emission spectrometer (ICP–OES), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT–IR), ultraviolet–visible spectroscopy (UV–vis), Raman spectroscopy, thermogravimetric analysis (TGA), x–ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. The prepared Cu0.5Co0.5Fe2O4@Arg–GO nanocomposite was used as an efficient catalyst for one–pot tandem oxidative synthesis of 2–phenylbenzimidazole derivatives in good yields.
- Ghadari, Rahim,Namazi, Hassan,Aghazadeh, Mohammad
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- Aerobic photooxidative synthesis of benzimidazoles from aromatic aldehydes and diamines using catalytic amounts of magnesium iodide
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This Letter proposes a safe, mild, and environmentally benign method for the synthesis of benzimidazoles from aromatic aldehydes and diamines by aerobic photooxidation using irradiation with visible light, a catalytic amount of magnesium iodide, which serves as both a Lewis acid and an oxidant, and molecular oxygen as the terminal oxidant.
- Nagasawa, Yoshitomo,Matsusaki, Yoko,Hotta, Toshiyuki,Nobuta, Tomoya,Tada, Norihiro,Miura, Tsuyoshi,Itoh, Akichika
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- Synthesis and evaluation of 2-aryl-1H-benzo[d]imidazole derivatives as potential microtubule targeting agents
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Microtubule targeting agents (MTAs) are the potential drug candidates for anticancer drug discovery. Disrupting the microtubule formation or inhibiting the de-polymerization process by a synthetic molecule can lead to an excellent anticancer drug candidat
- Lee, Jung-Seop,Nimse, Satish Balasaheb,Shinde, Pramod B.,Song, In-ho,Song, Keum-soo,Warkad, Shrikant Dashrath,Yeom, Gyu Seong
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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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- [Diaquo{bis(p-hydroxybenzoato-κ1O1)}(1-methylimidazole- κ1N1)}copper(II)]: Synthesis, crystal structure, catalytic activity and DFT study
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Metal-organic hybrid complexes often exhibit large surface area, pore volume, fascinating structures and potential applications including catalytic applications. Hence a new metal-organic hybrid complex [Diaquo{bis(p-hydroxybenzoato-κ1O1)}(1-methylimidazole- κ1N1)}copper(II)] was synthesized using conventional method. Physico-chemical characterization of the complex was performed with FTIR spectroscopy, single crystal X-ray diffraction, TGA, EPR and FESEM. Single crystal X-ray diffraction study suggests it to be three dimensional with space group P212121 (orthorhombic). The crystal achieves its three-dimensional structure and stability through extensive intermolecular hydrogen bonding. Hirshfeld surface analysis, catalytic activity and DFT study of the complex was also performed. The synthesized complex acts as good catalyst in benzimidazole synthesis with good recyclability as catalyst up to 5th run.
- Brahman, Dhiraj,Chhetri, Sailesh,Kamath, Amarjit,McArdle, Patrick,Sinha, Biswajit
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- Design, preparation, biological investigations and application of a benzoguanamine-based nickel complex for the synthesis of benzimidazoles
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The new magnetic-supported benzoguanamine-based nickel complex was prepared, characterized by various procedures and used as a capable heterogeneous nano-catalyst for the synthesis of diverse 2-phenyl-1H-benzo[d]imidazoles from the reaction o-phenylenedia
- Habibi, Davood,Heydari, Somayyeh,Karamian, Roya,Oliaei, Sajjad,Ranjbar, Nika
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- An Unexpected Formation of 2-Arylbenzimidazoles from α,α-Diiodo-α’-acetoxyketones and o-Phenylenediamines
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An unusual reactivity of the α,α-diiodo-α’-acetoxyketones with o-phenylenediamines is reported through the formation of 2-arylbenzimidazoles. A systematic study through a series of fruitful control experiments and isolation of key intermediates unravelled the unprecedented domino mechanism. This process involves a stepwise two-carbon fragmentation pathway through domino and sequential amidation–aziridination–decarbonylation–I2-mediated aminative cyclization–oxidation reactions. This strategy employs no additives like oxidant, metal catalyst, bases, and represents yet another novel reactivity profile of the building blocks α,α-diiodo-α’-acetoxyketones.
- Sadhukhan, Santu,Mondal, Swagata,Baire, Beeraiah
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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 0035-0078
(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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- Method for catalytically synthesizing phenylbenzimidazole compound by using copper complex
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The invention relates to a method for catalytically synthesizing a phenylbenzimidazole compound by using a copper complex, which comprises the following steps: in the presence of alkali, taking benzimidazole and halogenated hydrocarbon as raw materials, taking the copper complex containing meta-carborane ligand as a catalyst, and conducting reacting at room temperature to prepare the phenylbenzimidazole compound. Compared with the prior art, the method has the advantages that the halogenated hydrocarbon compound which is low in cost and easy to obtain is used as the substrate, the reaction of benzimidazole and halogenated hydrocarbon is efficiently catalyzed by using the copper complex, the phenylbenzimidazole compound is synthesized by a one-pot method, the reaction condition is mild, the universality is good, the catalytic efficiency is high, few byproducts are produced, the cost is relatively low, the product is easy to separate, and lots of waste residues cannot be generated.
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Paragraph 0051-0054
(2021/08/06)
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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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- Cu-Mn Bimetallic Complex Immobilized on Magnetic NPs as an Efficient Catalyst for Domino One-Pot Preparation of Benzimidazole and Biginelli Reactions from Alcohols
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An efficient magnetically recyclable bimetallic catalyst by anchoring copper and manganese complexes on the Fe3O4 NPs was prepared and named as Fe3O4@Cu-Mn. It was founded as a powerful catalyst for the domino one-pot oxidative benzimidazole and Biginelli reactions from benzyl alcohols as a green protocol in the presence of air, under solvent-free and mild conditions. Fe3O4@Cu-Mn NPs were well characterized by FT-IR, XRD, FE-SEM, TEM, VSM, TGA, EDX, DLS, and ICP analyses. The optimum range of parameters such as time, temperature, amount of catalyst, and solvent were investigated for the domino one-pot benzimidazole and Biginelli reactions to find the optimum reaction conditions. The catalyst was compatible with a variety of benzyl alcohols, which provides favorable products with good to high yields for all of derivatives. Hot filtration and Hg poisoning tests from the nanocatalyst revealed the stability, low metal leaching and heterogeneous nature of the catalyst. To prove the synergistic and cooperative effect of the catalytic system, the various homologues of the catalyst were prepared and then applied to a model reaction separately. Finally, the catalyst could be filtered from the reaction mixture simply, and reused for five consecutive cycles with a minimum loss in catalytic activity and performance. Graphic Abstract: A new magnetically recyclable Cu/Mn bimetallic catalyst has been developed for domino one-pot oxidation-condensation of benzimidazole and Biginelli reactions from alcohols. [Figure not available: see fulltext.]
- Nasseri, Mohammad Ali,Rezazadeh, Zinat,Kazemnejadi, Milad,Allahresani, Ali
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p. 1049 - 1067
(2020/09/11)
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- UV-visible light-induced photochemical synthesis of benzimidazoles by coomassie brilliant blue coated on W-ZnO@NH2nanoparticles
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Heterogeneous photocatalysts proffer a promising method to actualize eco-friendly and green organic transformations. Herein, a new photochemical-based methodology is disclosed in the preparation of a wide range of benzimidazoles through condensation of o-phenylenediamine with benzyl alcohols in the air under the illumination of an HP mercury lamp in the absence of any oxidizing species catalyzed by a new photocatalyst W-ZnO@NH2-CBB. In this photocatalyst, coomassie brilliant blue (CBB) is heterogenized onto W-ZnO@NH2 to improve the surface characteristics at the molecular level and enhance the photocatalytic activity of both W-ZnO@NH2 and CBB fragments. This unprecedented heterogeneous nanocatalyst is also identified by means of XRD, FT-IR, EDS, TGA-DTG, and SEM. The impact of some influencing parameters on the synthesis route and effects on the catalytic efficacy of W-ZnO@NH2-CBB are also assessed. The appropriate products are attained for both the electron-withdrawing and electron-donating substituents in the utilized aromatic alcohols. Furthermore, preparation of benzimidazoles is demonstrated to occur mainly via a radical mechanism, which shows that reactive species such as ·O2-, OH and h+ would be involved in the photocatalytic process. Stability and reusability studies also warrant good reproducibility of the nanophotocatalyst for at least five runs. Eventually, a hot filtration test proved that the nanohybrid photocatalyst is stable in the reaction medium. Using an inexpensive catalyst, UV-vis light energy and air, as a low cost and plentiful oxidant, puts this methodology in the green chemistry domain and energy-saving organic synthesis strategies. Finally, the anticancer activity of W-ZnO nanoparticles is investigated on MCF7 breast cancer cells by MTT assay. This experiment reveals that the mentioned nanoparticles have significant cytotoxicity towards the selected cell line.
- Chen, Ruijuan,Jalili, Zahra,Tayebee, Reza
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p. 16359 - 16375
(2021/05/19)
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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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- Photocatalytic green synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation over metal-free BCN: effect of crystallinity and N-B pair exposure
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Porous borocarbonitride (P-BCN), with the characteristics of enhanced crystallinity and improved N-B pair exposure, was prepared with a simple KCl-assisted molten salt strategy. Efficient heterogeneous photocatalytic tandem synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation was achieved firstly over the metal-free P-BCN using visible light and the green oxidant O2, with only water as a by-product. Variouso-thio/hydroxy/aminoanilines and alcohols or toluenes could be converted to the corresponding 2-substituted benzothiazoles, benzoxazoles and benzimidazoles with good to excellent photocatalytic performance. The improved photocatalytic performance in comparison to bulk BCN should be due to the crystallinity-enhancement-induced improvement in charge separation and transmission. The increased N-B pair exposure promoted superoxide radical generation due to the electron-enriched N atoms, as well as improved oxidation ability due to the valence band constructed by the B 2p orbital. This work presents a green and efficient synthetic strategy towards benzazoles and other fine chemicalsviametal-free heterogeneous photocatalysis.
- Cheng, Hongmei,Gao, Xue,Jiang, Heyan,Sun, Bin,Zang, Cuicui
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p. 7955 - 7962
(2021/12/27)
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- Application of sulfonic acid fabricated cobalt ferrite nanoparticles as effective magnetic nanocatalyst for green and facile synthesis of benzimidazoles
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This work represents the design and synthesis of efficient sulfonated cobalt ferrite solid acid catalyst. The synthesized solid acid green catalyst was characterized using various techniques viz. FT-IR, powder XRD, SEM, TEM and VSM. The obtained catalyst was used to synthesize biologically significant 2-substituted benzimidazole derivatives by condensation between o-phenylenediamine with various aromatic, aliphatic and heterocyclic aldehydes. High yield (up to 98 %), short reaction time (10?25 min), mild reaction condition, wide functional group tolerance, easy work-up procedure and excellent values of green chemistry metrices such as lower E factor (0.126), high RME value (88.83 %), carbon efficiency (100 %) and high atom economy (AE) value (90.65 %), are some salient features of the present catalytic system. Moreover, the catalyst recovery by simply using an external magnet and catalyst reusability up to 7 times without any significant loss in catalytic efficiency are some additional remarkable features of the current protocol.
- Yadav, Priyanka,Kakati, Praachi,Singh, Preeti,Awasthi, Satish K.
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- s-Tetrazine-functionalized hyper-crosslinked polymers for efficient photocatalytic synthesis of benzimidazoles
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Developing green-safe, efficient and recyclable catalysts is crucial for the chemical industry. So far, organic photocatalysis has been proved to be an environmentally friendly and energy-efficient synthetic technology compared with traditional metal catalysis. As a versatile catalytic platform, hyper-crosslinked polymers (HCPs) with large surface area and high stability are easily prepared. In this report, we successfully constructed two porous HCP photocatalysts (TZ-HCPs) featurings-tetrazine units and surface areas larger than 700 m2g?1through Friedel-Crafts alkylation reactions. The rational energy-band structures and coexisting micro- and mesopores endow TZ-HCPs with excellent activities to realize the green synthesis of benzimidazoles (28 examples, up to 99% yield, 0.5-4.0 h) in ethanol. Furthermore, at least 21 iterative catalytic runs mediated by TZ-HCP1D were performed efficiently, with 96-99% yield. This study of TZ-HCPs sheds light on the wide-ranging prospects of application of HCPs as metal-free and green photocatalysts for the preparation of fine chemicals.
- An, Wan-Kai,Zheng, Shi-Jia,Zhang, Hui-Xing,Shang, Tian-Tian,Wang, He-Rui,Xu, Xiao-Jing,Jin, Qiu,Qin, Yuchen,Ren, Yunlai,Jiang, Song,Xu, Cui-Lian,Hou, Mao-Song,Pan, Zhenliang
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supporting information
p. 1292 - 1299
(2021/02/26)
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- Fluorinated phosphoric acid as a versatile effective catalyst for synthesis of series of benzimidazoles, benzoxazoles and benzothiazoles at room temperature
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The present work describes synthesis of a series of benzimidazoles, benzoxazoles and benzothiazoles through the cyclization of 1, 2-phenylenediamine, 2-aminothiophenol, or 2-aminophenol with aryl, aliphatic and heteroaryl aldehydes. The present synthetic protocol is very much efficient in presence of 5 mol % fluorophosphoric acid as a catalyst in ethanol solvent at room temperature. Shorter reaction time, simple work-up technique, high yields and easy availability are specific compensations of the present synthetic approach.
- Mathapati, Sushil R.,Patil, Komal N.,Mathakari, Sujit S.,Suryawanshi, Appasaheb W.,Jadhav, Arvind H.
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p. 538 - 547
(2021/01/21)
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- Syntheses, characterization, and catalytic potential of novel vanadium and molybdenum Schiff base complexes for the preparation of benzimidazoles, benzoxazoles, and benzothiazoles under thermal and ultrasonic conditions
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A new ONO-tridentate Schiff base ligand (H2L) derived from 3-methoxysalicylaldehyde and nicotinic hydrazide was synthesized and characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, UV–Vis, and powder XRD studies. Then, oxovanadium(V) and dioxomolybdenum(VI) Schiff base complexes, VOL and MoO2L, were also prepared and characterized by different techniques. Moreover, the catalytic activities of both complexes were investigated for the synthesis of benzimidazoles, benzoxazoles, and benzothiazoles under reflux conditions as well as through ultrasonic irradiation. The results revealed several advantages of this procedure, including high product yields, short reaction times, facile work-up procedure, simplicity in operation, eco-friendly reaction conditions, and green aspects by avoiding toxic catalysts and solvents. Graphic abstract: [Figure not available: see fulltext.]
- Kargar, Hadi,Kargar, Khadijeh,Fallah-Mehrjardi, Mehdi,Munawar, Khurram Shahzad
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p. 593 - 605
(2021/06/21)
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- Al2O3/CuI/PANI nanocomposite catalyzed green synthesis of biologically active 2-substituted benzimidazole derivatives
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This work is generally focused on the synthesis of an efficient, reusable and novel heterogeneous Al2O3/CuI/PANI nanocatalyst, which has been well synthesized by a simple self-assembly approach where aniline is oxidized into PANI and
- Chandra, Ramesh,Hooda, Sunita,Kohli, Sahil,Rathee, Garima
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p. 7750 - 7758
(2021/06/16)
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- Ionic liquid-immobilized hybrid nanomaterial: an efficient catalyst in the synthesis of benzimidazoles and benzothiazoles via anomeric-based oxidation
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Abstract: In this study, a novel ionic liquid immobilized on silica-coated cobalt-ferrite magnetic nanoparticles. This novel hybrid nanostructure (CoFe2O4@SiO2@PAF-IL) was characterized by various microscopic and spectroscopic techniques including Fourier transformation infrared spectroscopy (FT–IR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (SEM), the electron-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM), and thermogravimetric analysis (TGA/DTG). The catalytic activity of prepared nanomaterial was considered in the synthesis of the benzothiazole and benzimidazole derivatives. This method has several advantages such as good to excellent yields, short reaction times, solvent-free and environmentally-benign conditions, and simple work-up. Besides, nanocatalyst can be easily separated from the reaction mixture with the external magnetic field and reused several times without any loss of its catalytic activity. Graphic abstract: [Figure not available: see fulltext.].
- Bodaghifard, Mohammad Ali,Shafi, Saeideh
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p. 677 - 687
(2020/09/18)
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- TEMPO supported amine functionalized magnetic titania: a magnetically recyclable catalyst for the aerobic oxidative synthesis of heterocyclic compounds
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Abstract: The present protocol uncover a new strategy to synthesize highly efficient solid TEMPO based catalyst in which 4-oxo-TEMPO was covalently tethered to the surface of amine functionalized magnetic titania. The chemical nature and structure of the
- Sharma, Sukanya,Choudhary, Anu,Sharma, Shally,Shamim, Tahira,Paul, Satya
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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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- Diversity in Heterocycle Synthesis Using α-Iminocarboxylic Acids: Decarboxylation Dichotomy
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Despite the structural similarity with imines, α-iminocarboxylic acids have seldom been used in heterocycles synthesis. The reactions of ortho-substituted anilines and arylglyoxylic acids in DMSO at 40 °C gave various benzo-fused five- to six-membered N-heterocycles in good to excellent yields. The reaction proceeds via intramolecular Michael addition of α-iminocarboxylic acids, generated in situ, with an ortho-substituted nucleophile, yielding an isolable unprecedented tetrahedral carboxylic acids, which upon decarboxylation without any aid of additional reagents forms the N-heterocycles. DMSO is crucial in this reaction, perhaps because of improved solubility and the ease of decarboxylation of these tetrahedral carboxylic acids. However, a copper-catalyzed reaction of ortho-substituted anilines and 2-bromoarylglyoxylic acids gave a dibenzo-fused seven-membered N-heterocycle under a basic reaction condition. Unlike intramolecular cyclization with α-iminocarboxylic acids in the first case, α-iminocarboxylic acid undergoes a competitive decarboxylation under the copper-catalyzed conditions, which upon subsequent heteroarylation form the heterocycles. Taken together, the study described herein represents two different modes of decarboxylation observed with α-iminocarboxylic acids, leading to the synthesis of divergent heterocycles and pharmaceuticals, which remained unexplored previously.
- Hunjan, Mandeep Kaur,Laha, Joydev K.
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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 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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- Visible light promoted tandem dehydrogenation-deaminative cyclocondensation under aerobic conditions for the synthesis of 2-aryl benzimidazoles/quinoxalines fromortho-phenylenediamines and arylmethyl/ethyl amines
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Visible light promoted domino synthesis of 2-aryl benzimidazoles is reported through the reaction ofortho-phenylenediamines and arylmethyl amines under aerobic conditions. The methodology has wide substrate scope and tolerates a wide range of functional groups affording the products in high yields. The use of arylethyl amines instead of arylmethyl amines gives 2-aryl quinoxalines.
- Sofi, Firdoos Ahmad,Sharma, Rohit,Rawat, Ravi,Chakraborti, Asit K.,Bharatam, Prasad V.
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supporting information
p. 4569 - 4573
(2021/03/22)
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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; 0156; 0157
(2020/02/20)
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- 2-ARYLBENZIMIDAZOLES AS PPARGC1A ACTIVATORS FOR TREATING NEURODEGENERATIVE DISEASES
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A genus of compounds encompassed by formula (III) and their use is disclosed: Formula (III). The compounds activate Ppargc1a and, as a consequence, are useful for treating a variety of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease, Parkinson's disease, Huntington's disease, frontotemporal degeneration, dementia with Lewy bodies, motor neuron diseases, and a demyelinating disease.
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Paragraph 85; 90
(2020/03/02)
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- Nanoporous Cu doped ZnS nanoparticles an efficient photo catalyst for the chemoselective synthesis of 2-substituted azoles via C-N arylation/ CSp3– H oxidation/ cyclization/dehydration sequence in visible light
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ZnS and Cu:ZnS nanoparticles were prepared by aqueous chemical method and characterized by several analytical tools. Nanoparticles have an average size of about ~ 18 nm and possess highly open mesopores, moderate surface area, and uniform morphology. UV–vis spectra designate that doping of Cu shifted the optical response of the ZnS nanoparticles in to a visible region. These Cu:ZnS nanoparticles were employed as a photocatalyst for chemoselective synthesis of 2-substituted azoles by the reaction of benzyl bromides and 1,2-Diaminobenzene or 2-Mercaptoaniline in visible light. Analogous experiments confirmed that the reaction were proceeds through one pot C–N arylation/ CSp3– H oxidation/ cyclization/dehydration sequence. The enhanced catalytic activity by doping could be attributed to the presence of trapping level generated by copper doping which augments the relaxation time of electron and holes so that they are easily available for the reaction. The method was also applicable for the synthesis of quinazolin-4(3H)-ones.
- Dandia, Anshu,Bansal, Sarika,Sharma, Ruchi,Kumar Mahawar, Dinesh,Rathore, Kuldeep S.,Lal Meena, Mohan,Parewa, Vijay
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- 1,2-Disubstituted Benzimidazoles by the Iron Catalyzed Cross-Dehydrogenative Coupling of Isomeric o-Phenylenediamine Substrates
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Benzimidazoles are common in nature, medicines, and materials. Numerous strategies for preparing 2-arylbenzimidazoles exist. In this work, 1,2-disubstituted benzimidazoles were prepared from various mono- and disubstituted ortho-phenylenediamines (OPD) by iron-catalyzed oxidative coupling. Specifically, O2 and FeCl3·6H2O catalyzed the cross-dehydrogenative coupling and aromatization of diarylmethyl and dialkyl benzimidazole precursors. N,N′-Disubstituted-OPD substrates were significantly more reactive than their N,N-disubstituted isomers, which appears to be relative to their propensity for complexation and charge transfer with Fe3+. The reaction also converted N-monosubstituted OPD substrates to 2-substituted benzimidazoles; however, electron-poor substrates produce 1,2-disubstituted benzimidazoles by intermolecular imino-transfer. Kinetic, reagent, and spectroscopic (UV-vis and EPR) studies suggest a mechanism involving metal-substrate complexation, charge transfer, and aerobic turnover, involving high-valent Fe(IV) intermediates. Overall, comparative strategies for the relatively sustainable and efficient synthesis of 1,2-disubstituted benzimidazoles are demonstrated.
- Foss, Frank W.,Palacios, Philip M.,Pierce, Brad S.,Thapa, Pawan,Tran, Tam
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p. 1991 - 2009
(2020/03/13)
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- Ultrafine Pt nanoparticles supported on a dendrimer containing thiol groups: An efficient catalyst for the synthesis of benzimidazoles and benzothiazoles from benzyl alcohol derivatives in water
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A novel and unique platform was prepared based on a dendrimer containing thiol groups supported on nanosilica (nSTDP), and ultrafine platinum nanoparticles were synthesized and immobilized on the thiol decorated branches of nSTPD. The new catalyst, (Ptnp?nSTDP), was characterized by different techniques such as FE-SEM, TEM, ICP, XPS and DR UV-vis. This heterogeneous catalyst presented an outstanding performance for the synthesis of benzimidazole and benzothiazole derivatives through a reaction between benzyl alcohol derivatives and 2-aminothiophenol or 1,2-phenylenediamine. No requirement for the pre-reduction of catalysts and using water as a green solvent make it an individual catalyst for these reactions. Furthermore, the catalyst can be easily recovered and reused five consecutive times in the production of benzimidazoles and benzothiazoles without significant leaching of Pt and loss of its activity which illustrated the chemical stability of the catalyst during the reaction.
- Bahadori, Mehrnaz,Landarani-Isfahani, Amir,Mirkhani, Valiollah,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Nori, Zahra Zamani,Tangestaninejad, Shahram
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p. 33137 - 33147
(2020/10/02)
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- Method for synthesizing benzimidazole compound through copper catalysis
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The invention relates to a method for synthesizing a benzimidazole compound by copper catalysis. The method comprises the following steps: dissolving o-phenylene diamine, benzyl alcohol or substitutedbenzyl alcohol in an organic solvent, adding a copper catalyst, carrying out reactions at a room temperature for 3-6 hours, and separating and purifying the reaction product to obtain the benzimidazole compound. Compared with the prior art, the method has the advantages of simple and green synthesis process, excellent selectivity, high yield and wide substrate range, and has great application potential in drug synthesis, natural product synthesis and the like.
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Paragraph 0026-0028
(2020/05/05)
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- Selective photocatalytic oxidation of aromatic alcohols to aldehydes with air by magnetic WO3ZnO/Fe3O4.: In situ photochemical synthesis of 2-substituted benzimidazoles
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Recently, visible light-driven organic photochemical synthesis has been a pioneering field of interest from academic and industrial associations due to its unique features of green and sustainable chemistry. Herein, WO3ZnO/Fe3O4 was synthesized, characterized, and used as an efficient magnetic photocatalyst in the preparation of a range of 2-substituted benzimidazoles via the condensation of benzyl alcohol and o-phenylenediamine in ethanol at room temperature for the first time. The key feature of this work is focused on the in situ photocatalytic oxidation of benzyl alcohols to benzaldehydes under atmospheric air and in the absence of any further oxidant. This new heterogeneous nanophotocatalyst was characterized via XRD, FT-IR, VSM and SEM. Short reaction time, cost-effectiveness, broad substrate scope, easy work-up by an external magnet, and excellent product yield are the major advantages of the present methodology. A number of effective experimental parameters were also fully investigated to clear broadness and generality of the protocol. This journal is
- Esmaeili, Effat,Li, Bozhi,Maleki, Behrooz,Namaghi, Mina S.,Tayebee, Reza
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p. 40725 - 40738
(2020/11/23)
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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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- 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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- Thiophene-embedded conjugated microporous polymers for photocatalysis
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Various photoactive building blocks can be incorporated into porous organic polymers (POPs). The intrinsic properties, such as various synthetic methods, outstanding inherent porosity, easy tunability, rigid conjugated skeletons and high stability, endow the polymeric organic networks with wonderful potential to act as heterogeneous photocatalytic platforms. However, exploitation of efficient synthetic strategies for metal-free and nontoxic heterogenous photocatalysts, and further insights into the photocatalytic process in organic transformations are still necessary. In this context, we report the concise synthesis of two polymeric frameworks (BTP-CMP and TBTP-CMP) incorporated into bithiophene and thiophthene units via a "bottom-up"strategy. BTP-CMP and TBTP-CMP were employed as heterogeneous photocatalysts in the synthesis of benzimidazoles, and exhibited excellent catalytic activity (up to 98% yield, at least 15 iterative runs). Therefore, the thiophene-embedded networks can serve as stable efficient and recyclable heterogeneous photocatalysts. Additionally, based on the catalytic results of control experiments and the energy band structures of the materials and intermediates, a possible photocatalytic reaction mechanism has been proposed.
- An, Wan-Kai,Cao, Zhan-Qi,Ding, San-Yuan,Du, Ya-Nan,Jiang, Song,Li, Zhi-Jun,Liu, Xiaobiao,Pan, Zhenliang,Qin, Yuchen,Song, Meirong,Wei, Pi-Feng,Zheng, Shi-Jia
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p. 5171 - 5180
(2020/09/07)
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- Cuprous complex containing meta-position carborane ligand as well as preparation method and application of cuprous complex
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The invention relates to a cuprous complex containing a meta-position carborane ligand as well as a preparation method and application of the cuprous complex. The cuprous complex is prepared by the following method: reacting n-BuLi with m-carborane diphenol, then adding 3-chloropyridine for continuous reaction, then adding CuI into a reaction system for continuous reaction, after the reaction is finished, separating the reaction product to obtain the cuprous complex containing the m-carborane ligand, and applying the cuprous complex to one-pot synthesis of the benzimidazole derivative. Compared with the prior art, the method has the advantages that o-phenylenediamine and aldehyde compounds which are cheap and easy to obtain can be used as substrates, the reaction conditions are mild, the universality is good, the catalytic efficiency is high, byproducts are few, the cost is low, products are easy to separate, and generation of a large amount of waste residues is avoided.
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Paragraph 0046-0049
(2020/10/14)
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- Three-Way Chemoselectivity Switching through Coupled Equilibria
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Controlling the chemoselectivity of reactions operating on complex mixtures, including those found in biological and petrochemical feedstocks or in the primordial soup from which life emerged, is generally challenging. The selectivity of imine oxidation c
- Puangsamlee, Thamon,Miljani?, Ognjen ?.
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supporting information
p. 5900 - 5904
(2020/08/05)
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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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- Small-molecular OLED electron transport material and preparation method and application thereof
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The invention belongs to the technical field of organic electron transport materials, and relates to a small-molecular OLED electron transport material and a preparation method and an application thereof. Compounds of the small-molecular OLED electron transport material comprise an aromatic fused heterocycle and an aryl-substituted benzimidazole group which are connected with each other. The two kinds of groups not only enable the compounds to have good electron accepting capability, but also tend to planarity to be beneficial to molecular stacking, and are beneficial to combination of holes and electrons and exciton generation, so that the electron mobility of the material is improved, and the device efficiency is improved; meanwhile, the combination of the two enables carrier transmission to be balanced; when the small-molecular OLED electron transport material is applied to an organic light-emitting device and used as an electron transport layer, the device shows the advantages of low driving voltage and high light-emitting efficiency, and is superior to an existing common OLED device.
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Paragraph 0087-0090
(2020/06/17)
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- An Efficient Greener Approach for N-acylation of Amines in Water Using Benzotriazole Chemistry
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A straightforward, mild and cost-efficient synthesis of various arylamides in water was accomplished using versatile benzotriazole chemistry. Acylation of various amines was achieved in water at room temperature as well as under microwave irradiation. The developed protocol unfolds the synthesis of amino acid aryl amides, drug conjugates and benzimidazoles. The environmentally friendly synthesis, short reaction time, simple workup, high yields, mild conditions and free of racemization are the key advantages of this protocol.
- Ibrahim, Tarek S.,Seliem, Israa A.,Panda, Siva S.,Al-Mahmoudy, Amany M.M.,Abdel-Samii, Zakaria K.M.,Alhakamy, Nabil A.,Asfour, Hani Z.,Elagawany, Mohamed
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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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- 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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- Iron(0)-Catalyzed Transfer Hydrogenative Condensation of Nitroarenes with Alcohols: A Straightforward Approach to Benzoxazoles, Benzothiazoles, and Benzimidazoles
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The iron-catalyzed hydrogen transfer strategy has been applied to the redox condensation of o-hydroxynitrobenzene with alcohol, leading to the formation of benzoxazole derivatives. A wide range of 2-substituted benzoxazoles were synthesized in good to excellent yields without the addition of an external redox agent. A series of control experiments provided a plausible mechanism. Furthermore, the reaction system was successfully extended to the synthesis of benzothiazoles and benzimidazoles.
- Putta, Ramachandra Reddy,Chun, Simin,Choi, Seung Hyun,Lee, Seok Beom,Oh, Dong-Chan,Hong, Suckchang
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p. 15396 - 15405
(2020/12/02)
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- Redox-Neutral Photocatalytic Radical Cascade Cyclization for the Synthesis of CH2CN/CF2COOEt/CF3-Containing Benzo[4,5]imidazo[2,1-a]isoquinolin-6(5 H)-One Derivatives
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A novel method for the synthesis of benzo[4,5]imidazo[2,1-A]isoquinolin derivatives via visible-light-induced radical cascade cyclization is described. By using N-methacryloyl-2-phenylbenzoimidazoles and diverse radical precursors, various benzo[4,5]imidazo[2,1-A]isoquinolin derivatives containing CH2CN/CF2COOEt/CF3 can be formed in good to excellent yields under mild reaction conditions. This method exhibits good functional group tolerance and a wide range of substrate scope.
- Liu, Liang,Yang, De-Yong,He, Yan-Hong,Guan, Zhi
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p. 11892 - 11901
(2020/10/23)
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- Synthesis of benzimidazoles by two methods (C–H functionalization and condensation reaction) catalyzed by α-zirconium hydrogen phosphate-based nanocatalyst
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In this report, two heterogeneous nanocatalysts based on α-zirconium hydrogen phosphate were applied. These heterogeneous catalysts have demonstrated the promising catalytic activity for the synthesis of 2-substituted benzimidazoles in two different methods. One of these reactions is the functionalization of the C–H bond and the formation of C–N bond, and the other reaction involves the condensation reaction between aldehydes and 1,2-phenylenediamine. The activity of both catalysts was compared in two methods, and the superior catalyst was introduced. The prepared catalysts are easily separated from the reaction mixture by centrifugation and reused several times without significant loss of activity.
- Hajipour, Abdol R.,Zakery, Saedeh,Khorsandi, Zahra
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p. 1919 - 1931
(2020/05/28)
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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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