International Research Journal of Pure and Applied Chemistry

Aim: To synthesis 3,4-Dihydropyrimidin-2(1H)-ones and 3,4-Dihydropyrimidin-2(1H)-thiones using phenol formaldehyde resin as a catalyst.

Study Design: Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and 3,4-Dihydropyrimidin-2(1H)-thiones by cyclocondensation of ethyl or methyl acetoacetates, aldehydes and urea or thiourea using Bronsted acidic phenol-formaldehyde liquid resin as homogenous catalyst and as reaction medium under solvent-free condition.

Methodology: Cyclocondensation of aromatic aldehyde, (thio) urea, ketoester was done in the presence of phenol-formaldehyde resin at 110°C with stirring for appropriate time. The progress of the reaction was monitored by TLC. After completion of the reaction. The product was extracted by ethyl acetate solvent. The product was purified either by recrystallization in hot ethanol or by column chromatography. All the products were thoroughly characterised by FT-IR, ¹H-NMR, ¹³C-NMR, Mass spectral and CHN elemental analysis.

Results: 15 different 3,4-Dihydropyrimidin-2(1H)-ones were synthesized and characterized thoroughly.

Conclusion: We have developed an efficient method for one pot synthesis of 3,4-dihydropyrimidine-2-ones (DHPOs) and 3,4-dihydropyrimidine-2-thiones (DHPTs) by employing phenol-formaldehyde liquid resin as catalyst as well as medium for the Biginelli reaction. The advantages of this procedure includes not only free from volatile organic solvent, toxic metal catalyst, strong acid, but simple procedure, shorter reaction time, easy workup, and reusable catalysts conditions, and formation of pure products in good to excellent yields.