A Simple and Efficient One-pot Synthesis of 4-alkyl-3,4-dihydropyrimidin-2(1 H )-ones

Abstract

4-Alkyl-3,4-dihydropyrimidin-2(1H)-ones possess a number of important properties in comparison with their 4-aryl analogues. We show that these compounds can be synthesised by a simple one-pot reaction of urea or thiourea, different aliphatic aldehydes (from acetaldehyde to valeraldehyde) and various dicarbonyl compounds (ethyl acetoac-etate, pentane-2,4-dione, N-(4-chlorophenyl)-3-oxobutanamide, acetoacetaldehyde dimethylacetal) in refluxing DMF or HOAc without use of any catalyst. The methylation of 4-alkyl-5-C(O)R-3,4-dihydropyrimidin-2(1H)-ones leads to 1-methyl derivatives.