Poly(4-vinylpyridinium) hydrogen sulfate: an efficient catalyst for the synthesis of xanthene derivatives under solvent-free conditions

2012 ◽  
Vol 2 (11) ◽  
pp. 2211 ◽  
Author(s):  
Nader Ghaffari Khaligh
Keyword(s):  
Solvent Free ◽  
Hydrogen Sulfate ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Xanthene Derivatives

Synthesis of Dihydropyrimidinones (DHPMs) and Hexahydro Xanthene Catalyzed by 1,4-Diazabicyclo [2.2.2] Octane Triflate Under Solvent-Free Condition

2019 ◽  
Vol 16 (5) ◽  
pp. 776-786 ◽  
Author(s):  
Deepa ◽  
Geeta D. Yadav ◽  
Mohd J. Aalam ◽  
Pooja Chaudhary ◽  
Surendra Singh
Keyword(s):  
Ethyl Acetoacetate ◽  
Biginelli Reaction ◽  
Solvent Free ◽  
Efficient Catalyst ◽  
Solvent Free Condition ◽  
Solvent Free Conditions ◽  
Xanthene Derivatives ◽  
Different Temperatures ◽  
Flash Column Chromatography ◽  
Biginelli Condensation

Objective:DABCO salts were evaluated as catalysts for the Biginelli reaction between 4- methoxybenzaldehyde, urea and ethyl acetoacetate under solvent-free conditions. 1,4-Diazabicyclo [2.2.2] octane triflate was found to be a simple, inexpensive, highly efficient catalyst for Biginelli reaction for a variety aromatic aldehyde with urea and ethyl acetoacetate at 80°C afforded corresponding 3,4-dihydropyrimidinones in 50-99% yields after 30-120 minutes. 1,3-Cyclohexadione was used in place of ethyl acetoacetate in the absence of urea this methodology is giving hexahydro xanthene derivatives in good to excellent yields after 3-4 hours.Methods:DABCO salt 4 (5 mol%), 4-methoxybenzaldehyde (0.73 mmol) and urea (0.73 mmol) were stirred for 10 minutes at 80°C, then ethyl acetoacetate (1.5 equiv.) was added and reaction mixture was stirred at 80°C for specified time. The resulting solution was stirred continuously and progress of the reaction was followed by TLC. The crude reaction mixture was purified by flash column chromatography on silica gel (hexane/ethyl acetate (1:2)) to give pure desired product.Results:Reaction conditions of the Biginelli reaction were optimized using 4-methoxybenzaldehyde (0.73 mmol), urea (0.73 mmol), and ethyl acetoacetate (5 equiv.) as model substrates catalyzed by 1,4-Diazabicyclo [2.2.2] octane triflate (5 mol%) in a different solvents, screening of different catalysts and different temperatures. Neat condition was found to be the best for the Biginelli condensation and corresponding 3,4- dihydropyrimidinones was obtained in good to excellent yields. When the reaction was carried out with benzaldehyde derivatives and cyclohexane-1,3-dione in place of ethyl acetoacetate in the absence of urea, solely corresponding hexahydro xanthene derivatives were obtained in 61-91% yields.Conclusion:In conclusion, we have applied salts of 1,4-Diaza-bicyclo [2.2.2] octane as catalysts in the Biginelli condensation and corresponding 3,4-dihydropyrimidinones were obtained in 50- 99% yields under solvent free conditions. This methodology is having advantages like simple work-up; low loading of catalyst and reaction was performed at moderate temperature under solvent-free conditions.

scholarly journals Mg(HSO4)2/SiO2 as a Highly Efficient Catalyst for the Green Preparation of 2-Aryl-1,3-Dioxalanes/Dioxanes and Linear Acetals

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Fariba Jafari ◽  
Saeed Khodabakhshi
Keyword(s):  
Organic Solvents ◽  
Environmentally Friendly ◽  
Solvent Free ◽  
High Yield ◽  
Hydrogen Sulfate ◽  
Green Process ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Work Up ◽  
Environmentally Friendly Method

Silica-supported magnesium hydrogen sulfate has been used as a recyclable catalyst for the synthesis of some linear and cyclic aromatic acetals under solvent-free conditions. This environmentally friendly method has advantages, such as high yield of products, simple work-up procedure, and avoidance of the organic solvents, which will contribute in serving as a green process greatly.

Morpholinium hydrogen sulfate (MHS) ionic liquid as an efficient catalyst for the synthesis of bio-active multi-substituted imidazoles (MSI) under solvent-free conditions

2017 ◽  
Vol 72 (1) ◽  
pp. 23-33 ◽  
Author(s):  
Adel A. Marzouk ◽  
Antar A. Abdelhamid ◽  
Shaaban K. Mohamed ◽  
Jim Simpson
Keyword(s):  
Ionic Liquid ◽  
Reaction Times ◽  
Aromatic Aldehydes ◽  
Solvent Free ◽  
Biologically Active ◽  
High Yield ◽  
Hydrogen Sulfate ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Very High

AbstractMorpholinium hydrogen sulfate as an ionic liquid was employed as a catalyst for the synthesis of a biologically active series of multi-substituted imidazoles by a four-component reaction involving the combination of benzil with different aromatic aldehydes, ammonium acetate, and 1-amino-2-propanol under solvent-free conditions. The key advantages of this method are shorter reaction times, very high yield, and ease of processing. Furthermore, the resulting products can be purified by a non-chromatographic method and the ionic liquid catalyst is reusable. All of these novel compounds have been fully characterized from spectral data. The X-ray crystal structures of two representative molecules are also detailed.

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