- Metal free montmorillonite KSF clay catalyzed practical synthesis of benzoxazoles and benzothiazoles under aerobic conditions
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An efficient method for the synthesis of benzoxazoles and benzothiazoles via montmorillonite KSF clay catalyzed condensation reaction between 2-aminophenols or 2-aminothiophenols and β-diketones is reported. The efficiency of the reaction reflects from the wide substrate scope with electronic differentiation on aryls. The reaction is metal free and proceeds without the exclusion of air or moisture, and further the catalyst can be recycled up to 3–5 catalytic cycles.
- Kummari, Vijaya Babu,Chiranjeevi, Kalavakuntla,Suman Kumar, Alleni,Kumar, Rathod Aravind,Yadav, Jhillu Singh
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supporting information
p. 3335 - 3342
(2019/11/11)
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- One-pot synthesis of benzoxazoles via the metal-free ortho-C-H functionalization of phenols with nitroalkanes
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PPA-activated nitroalkanes are employed in the design of a one-pot cascade transformation involving metal-free and oxidant-free direct ortho-C-H functionalization, followed by Beckman rearrangement and intramolecular cyclocondensation to produce benzoxazoles and benzobisoxazoles directly from easily available phenols.
- Aksenov, Nicolai A.,Aksenov, Alexander V.,Nadein, Oleg N.,Aksenov, Dmitrii A.,Smirnov, Alexander N.,Rubin, Michael
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p. 71620 - 71626
(2015/09/08)
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- Synthesis of benzoxazoles from 2-aminophenols and β-diketones using a combined catalyst of br?nsted acid and copper iodide
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Cyclization reactions of 2-aminophenols with β-diketones catalyzed by a combination of Br?nsted acid and CuI are presented. Various 2-substituted benzoxazoles were obtained through these reactions. Different substituents such as methyl, chloro, bromo, nitro, and methoxy on 2-aminophenol are tolerated under the optimized reaction conditions.
- Mayo, Muhammad Shareef,Yu, Xiaoqiang,Zhou, Xiaoyu,Feng, Xiujuan,Yamamoto, Yoshinori,Bao, Ming
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p. 6310 - 6314
(2014/07/21)
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- Application of nano SnO2 as a green and recyclable catalyst for the synthesis of 2-aryl or alkylbenzoxazole derivatives under ambient temperature
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Application of nano SnO2 as an efficient and benign catalyst has been explored for the synthesis of 2-aryl or alkylbenzoxazole derivatives via condensation reaction of aldehyde with 2-aminophenol. The reactions proceed under heterogeneous and mild conditions in ethanol at room temperature to provide 2-aryl or alkylbenzoxazoles in high yields.
- Vahdat, Seyed Mohammad,Raz, Shima Ghafouri,Baghery, Saeed
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p. 579 - 585
(2014/07/07)
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- A green and efficient protocol for the synthesis of quinoxaline, benzoxazole and benzimidazole derivatives using heteropolyanion-based ionic liquids: As a recyclable solid catalyst
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In this paper, we introduce two nonconventional ionic liquid compounds which are composed of propane sulfonate functionalized organic cations and heteropolyanions as green solid acid catalysts for the highly efficient and green synthesis of 2,3-disubstitutedquinoxaline derivatives. These ionic liquids are in the solid state at room temperature and the synthesis is carried out via the one-pot condensation reaction of various o-phenylenediamine with 1,2-diketone derivatives. Benzoxazole and benzimidazole derivatives were also synthesized by these novel catalysts via the one-pot condensation from reaction orthoester with o-aminophenol (synthesis of benzoxazole derivatives) and ophenylenediamine (synthesis of benzimidazole derivatives). All experiments successfully resulted in the desired products. The described novel synthesis method has several advantages of safety, mild condition, high yields, short reaction times, simplicity and easy workup compared to the traditional method of synthesis.
- Vahdat, Seyed Mohammad,Baghery, Saeed
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p. 618 - 627
(2013/09/12)
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- Tungstate sulfuric acid as an efficient catalyst for the synthesis of benzoxazoles and benzothiazoles under solvent-free conditions
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Tungstate sulfuric acid (TSA) has been found to be an efficient and reusable catalyst for the synthesis of benzoxazole and benzothiazole derivatives via reactions of orthoesters with o-aminophenols or o-aminothiophenols in high yields.
- Farahi, Mahnaz,Karami, Bahador,Azari, Masume
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p. 1029 - 1034
(2013/11/06)
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- 1,3-Dibromo-5,5-dimethylhydantoin as an efficient homogeneous catalyst for synthesis of benzoxazoles, benzimidazoles, and oxazolo[4,5-b]pyridines
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A simple and highly efficient method for synthesis of benzoxazoles, benzimidazoles, and oxazolo[4,5-b]pyridines is described. Condensation of orthoesters with o-substituted anilines or 2-amino-3-hydroxypyridine was performed in the presence of catalytic amounts of commercially available, inexpensive, and moisture-stable 1,3-dibromo-5,5-dimethylhydantoin under solvent-free conditions. The corresponding heterocycles were obtained in good to excellent yields. The main advantages of the present procedure are mild reaction conditions, short reaction times, high yields of products, easy work-up, and absence of solvent. Graphical abstract: [Figure not available: see fulltext.]
- Hojati, Seyedeh Fatemeh,Maleki, Behrooz,Beykzadeh, Zahra
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experimental part
p. 87 - 91
(2011/09/19)
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- Mild and efficient synthesis of benzoxazoles, benzothiazoles, benzimidazoles, and oxazolo[4,5-b]pyridines catalyzed by Bi(III) salts under solvent-free conditions
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A series of benzoxazoles, benzothiazoles, benzimidazoles, and oxazolo[4,5-b]pyridines was efficiently synthesized from the reactions of o-aminophenols, o-aminothiophenol, o-phenylenediamines, and 2-amino-3- hydroxypyridine with orthoesters in the presence of catalytic amounts of Bi(III) salts, such as Bi(TFA)3, Bi(OTf)3, and BiOClO4 ? xH2O under solvent-free conditions. The remarkable features of this new protocol are high conversion, very short reaction times, cleaner reaction profiles under solvent-free conditions, straightforward procedure, and use of relatively non-toxic catalysts. Springer-Verlag 2007.
- Mohammadpoor-Baltork, Iraj,Khosropour, Ahmad R.,Hojati, Seyedeh F.
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p. 663 - 667
(2008/02/07)
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- Use of zeolite catalysts for efficient synthesis of benzoxazoles via Beckmann rearrangement
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Substituted benzoxazoles have been synthesized in very good yields starting from o-acylphenol oximes via Beckmann rearrangement using zeolite catalysis.
- Bhawal,Mayabhate,Likhite,Deshmukh
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p. 3315 - 3321
(2007/10/03)
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