- 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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supporting information
(2019/12/26)
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- Gadolinium (III) chloride catalyzed facile synthesis of 2-substituted benzimidazoles under solvent-free conditions
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A series of 2-substituted benzimidazoles have been prepared from o-diamines and 1,3-dicarbonyl compounds using Gadolinium chloride as a catalyst under solvent free condition in good yields. Gadolinium chloride has been demonstrated as a mild and efficient catalyst.
- Sathaiah,Venkat Lingaiah,Chandra Shekhar,Ravi Kumar,Raju,Shanthan Rao
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p. 953 - 957
(2015/08/19)
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- Novel silica tungstic acid (STA): Preparation, characterization and its first catalytic application in synthesis of new benzimidazoles
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A novel silica tungstic acid (STA) as a highly efficient catalyst has been synthesized and employed for the cyclocondensation of 1,2-phenylenediamines with orthoesters under solvent-free conditions. Catalyst loadings can be as low as 1 mol% to give high yields of the corresponding benzimidazoles at 80 °C. To make the catalyst, sodium tungstate reacted with silica chloride under refluxing n-hexane. The STA as a novel solid acid was characterized by X-ray fluorescence, X-ray diffraction, and Fourier transform infrared spectroscopy.
- Karami, Bahador,Ghashghaee, Vahideh,Khodabakhshi, Saeed
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experimental part
p. 71 - 75
(2012/06/16)
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- Novel Approach to Benzimidazoles Using Fe3O4 Nanoparticles as a Magnetically Recoverable Catalyst
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Magnetically recoverable Fe3O4 nanoparticles have been synthesized as a catalyst for the cyclocondensation of 1,2-phenylenediamines with orthoesters under solvent-free conditions. Catalyst loadings can be as low as 1 mol% to give high yields of the corresponding benzimidazole derivative at 80 °C. This green method offers significant advantages in terms of its simplicity, low catalyst loadings, high product yields, and non-toxic nature. The Fe3O4 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy.
- Karami, Bahador,Nikoseresht, Shaghayegh,Khodabakhshi, Saeed
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p. 298 - 301
(2016/04/10)
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- A rapid access to novel and known benzimidazole derivatives using silica chloride as a reusable catalyst
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A new application of silica chloride as an easily available and reusable solid acid catalyst for the synthesis of benzimidazole and its derivatives through the condensation of o-phenylenediamines and orthoesters under thermal and solvent-free conditions is described. This novel and eco-friendly method is very cheap and has many advantages including excellent yields, short reaction time, and simple work-up procedure. Copyright
- Karami, Bahador,Ghashghaee, Vahideh,Khodabakhshi, Saeed
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experimental part
p. 959 - 964
(2012/05/31)
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- Novel approach to benzimidazoles using Fe3O4 nanoparticles as a magnetically recoverable catalyst
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Magnetically recoverable Fe3O4 nanoparticles have been synthesized as a catalyst for the cyclocondensation of 1,2- phenylenediamines with orthoesters under solvent-free conditions. Catalyst loadings can be as low as 1 mol to give high yields of the corresponding benzimidazole derivative at 80°C. This green method offers significant advantages in terms of its simplicity, low catalyst loadings, high product yields, and non-toxic nature. The Fe3O4 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy.
- Karami, Bahador,Nikoseresht, Shaghayegh,Khodabakhshi, Saeed
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experimental part
p. 298 - 301
(2012/06/29)
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- Tungstate sulfuric acid: Preparation, characterization, and application in catalytic synthesis of novel benzimidazoles
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Tungstate sulfuric acid (TSA) was prepared, characterized, and applied for direct synthesis of novel and known benzimidazoles through a condensation reaction of o-phenylenediamines with orthoesters under solvent-free conditions. TSA was characterized by powdered X-ray diffraction (XRD), X-ray fluorescence (XRF), and FTIR spectroscopy. This novel and eco-friendly method is very cheap and has many advantages such as excellent yields, recyclable and eco-friendly catalyst, and simple work-up procedure.
- Karami, Bahador,Khodabakhshi, Saeed,Haghighijou, Zahra
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p. 684 - 690
(2013/07/26)
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- Microwave-assisted synthesis of polysubstituted benzimidazoles by heterogeneous Pd-catalyzed oxidative C-H activation of tertiary amines
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Tertiary amines can be used in place of aldehydes and carboxylic derivatives as partners in the synthesis of benzimidazoles. Dehydrogenative amine activation under heterogeneous catalysis was developed for the direct transformation of tertiary amines into benzimidazoles. Good yields and efficient recovery and recycling of the catalyst are some of the advantages of this new methodology, which shows that a simple alkene is used as the overall oxidative agent. Enhanced reaction rates were observed by using focused microwave heating.
- De Luca, Lidia,Porcheddu, Andrea
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supporting information; experimental part
p. 5791 - 5795
(2011/11/06)
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- Reactions of 4-benzoyl-o-phenylenediamine: Synthesis of dihydro-1,5-benzodiazepines, quinoxalines and benzimidazoles
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Condensation of 4-benzoyl-o-phenylenediamine (1) with different ketones under mild conditions using acetic acid as catalyst results in dihydro-benzodiazepines, quinoxalines and benzimidazoles.
- Rao, P Shanthan,Venkataratnam, R V
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p. 733 - 735
(2007/10/02)
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- ENZYMATIC CYCLIZATION INVOLVING INTRAMOLECULAR MICHAEL ADDITION BY CATALASE: FORMATION OF 2-METHYLBENZIMIDAZOLES
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Catalase-mediated intramolecular cyclization of ethyl β-2-aminoanilinocrotonates gives 2-methylbenzimidazoles in good yields
- Kamal, Ahmed,Hashim, Riaz
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p. 969 - 970
(2007/10/02)
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