- Nanosilica molybdic acid: synthesis, characterization and application as a green and reusable catalyst for the Pechmann condensation
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Abstract: Nanosilica molybdic acid (SMA NPs) was founded as an efficient and recyclable nanocatalyst for the synthesis of coumarin derivatives in excellent yields with good purity. Nano-SMA as a new solid acid was characterized by X-ray fluorescence, X-ray diffraction, energy-dispersive X-ray analyzer, transmission electron microscopy and Fourier transform infrared spectroscopy. Coumarin derivatives were obtained via the Pechmann condensation reaction of phenols and β-ketoesters at 80?°C under solvent-free conditions. The main advantages of the present procedure are high yields, shorter reaction time and green chemistry procedure, simple work-up and inexpensive and reusability of the catalyst. Graphical Abstract: [Figure not available: see fulltext.]
- Kiani, Mahtab,Karami, Bahador
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p. 655 - 663
(2017/01/17)
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- Preparation of a novel, efficient, and recyclable magnetic catalyst, γ-Fe2O3@HAp-Ag nanoparticles, and a solvent- and halogen-free protocol for the synthesis of coumarin derivatives
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In this protocol, Ag supported on the hydroxyapatite-core–shell magnetic γ-Fe2O3nanoparticles (γ-Fe2O3@HAp-Ag NPs) as a novel, efficient, and magnetically recyclable catalyst is synthesized, and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The use of the catalyst is described in the synthesis of coumarin derivatives by the Pechmann condensation of various phenols with β-ketoesters under solvent- and halogen-free conditions at 80?°C. This novel and inexpensive method offers advantages, such as recyclability simple experimental protocol, short reaction time, minimal work-up procedure, and excellent yields of products, together with desirable, eco-friendly, green aspects by avoiding toxic elements and solvents, and ease of recovery from the reaction mixture using an external magnet.
- Abbasi, Zahra,Rezayati, Sobhan,Bagheri, Maryam,Hajinasiri, Rahimeh
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- Environmentally sustainable magnetic solid sulfonic acid: An efficient and reusable catalyst for the Pechmann reaction
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Abstract An environmentally benign sulfonic acid nanocomposite based on Fe3O4@SiO2 core-shell magnetic nanoparticles, Fe3O4@SiO2@Et-PhSO3H, was prepared and the acidity and utility of the catalyst were explored for the synthesis of a diverse range of coumarin derivatives under solvent-free conditions. The catalyst shows potential for scale up in the synthesis of coumarins with high purity and was easily separated by using an external magnet. The recovered catalyst was reused in seven cycles without any significant loss of activity.
- Mobaraki, Akbar,Yasham, Shahriar,Movassagh, Barahman
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supporting information
p. 1263 - 1268
(2015/06/02)
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- Synthesis of the coumarins via pechmann method in the presence of environmentally friendly Y(NO3)3×6H2O
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Several substituted coumarins can be prepared in high yield and purity by direct reaction of β-keto esters and phenol derivatives in the presence of a catalytic amount Y(NO3)3×6H2O as Lewis acid and at ambient temperature under solvent-free conditions. Several substituted coumarins can be prepared in high yield and purity by direct reaction of β-keto esters and phenol derivatives in the presence of a catalytic amount Y(NO3)3×6H2O as Lewis acid and at ambient temperature under solvent-free conditions. This method that is based on Pechmann condensation is very easy and rapid reaction for the synthesis of coumarin derivatives. Copyright
- Karami, Bahador,Kiani, Mahtab
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p. 213 - 216
(2014/05/06)
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- ZrOCl2.8H2O/SiO2: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction
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Silica gel supported zirconyl chloride octahydrate was found to be an efficient and recyclable catalyst for the synthesis of a series of biologically important molecules in high turnover numbers and rates. Several substituted coumarins can be prepared in high yield and purity by direct reaction of β-keto esters and phenol derivatives in the presence of a catalytic amount of ZrOCl2.8H2O/SiO2 as Lewis acid and at ambient temperature under solvent-free conditions. This method which is called Pechmann condensation is a very easy and a rapid reaction for the synthesis of coumarin derivatives.
- Karami, Bahador,Kiani, Mahtab
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experimental part
p. 62 - 67
(2012/01/15)
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- Cux2 (x =cl, br) as catalysts for pechmann reaction: Synthesis of 4-substituted coumarins
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CuX2 (X=Cl, Br) are found to be efficient catalysts (10 mol%) for the Pechmann condensation reaction of phenols and b-ketoesters to give 4-substituted coumarins under solvent-free conditions. The yields of coumarin derivatives obtained via this
- Wang, Yi,Xu, Feng,Tian, You-Ping,Li, Hui-Li,Wang, Jian-Jun
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experimental part
p. 339 - 341
(2009/12/25)
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- Microwave-promoted automated synthesis of a coumarin library
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A 30-membered library of coumarins has been synthesized in a microwave-assisted Pechmann reaction using neat trifluoroacetic acid both as an acidic reagent and a reaction medium. Alternatively, polymer-supported sulfonic acid Amberlyst-15 could also be employed to facilitate the formation of coumarins. The use of a specially-built microwave synthesizer with liquid handling tools rendered the automated synthesis of a coumarin library feasible.
- Katkevi?s,Kontijevskis,Mutule,Sūna
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p. 151 - 159
(2008/12/20)
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