Organic chemistry
Asadollah Farhadi; Milad Ramyar; Mohammad Ali Takassi
Volume 6, Issue 3, pp. 218-324, Serial No. 20 , July 2018, , Pages 266-270
Abstract
A protocol for the synthesis of 1,4-dihydropyridines (Hantzsch type-products) was developed by means of a three-component condensation of an aldehyde, a β-dicarbonyl compound, ammonium acetate and nano Al2O3/KF as catalyst. This reaction was carried out under different conditions including i) solvent-free ...
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A protocol for the synthesis of 1,4-dihydropyridines (Hantzsch type-products) was developed by means of a three-component condensation of an aldehyde, a β-dicarbonyl compound, ammonium acetate and nano Al2O3/KF as catalyst. This reaction was carried out under different conditions including i) solvent-free ii) and reflux in different solvents. In all conditions, the desired products were obtained in high yields after relatively short reaction times. Nevertheless, the reactions proceed faster and in higher yields when they were carried out in ethanol. Compared to the classical Hantzsch reaction conditions and previously reported protocols, this protocol has the advantages of consistently excellent yields and short reaction times. After the reaction, the catalyst could be recovered easily.
Organic chemistry
Asadollah Farhadi; Mohammad Ali Takassi; Lila Hejazi
Volume 5, Issue 1, pp. 1-120, Serial No. 14 , January 2017, , Pages 35-41
Abstract
The chemistry of 2-oxo-1,2,3,4-tetrahydropyrimidines began to develop toward the end of 1893 year, when the first representatives of this class compounds were reported by P. Biginelli. Despite prior reports of several really effective catalytic and non-catalytic approaches towards Biginelli-type products, ...
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The chemistry of 2-oxo-1,2,3,4-tetrahydropyrimidines began to develop toward the end of 1893 year, when the first representatives of this class compounds were reported by P. Biginelli. Despite prior reports of several really effective catalytic and non-catalytic approaches towards Biginelli-type products, an overwhelming number of new catalysts for the Biginelli reaction have been recently published. Most of the catalysts are somewhat exotic, expensive, harmful and even ineffective in the absence of acidic additives. This work reports on the preparation of 2-oxo-1,2,3,4-tetrahydropyrimidines using the NaF as catalyst. One-pot condensation reactions were carried out for various aryl aldehydes, ethyl acetoacetate, acetyl acetone and urea under solvent-free conditions at 100 °C and afforded the target molecules in good to excellent yields. The advantages of this method are high yield of product, short reaction time, and separation of this catalyst is very comfortable. Furthermore, according to the experimental data, we have proposed the suitable mechanism.