A library of dihydropyrimidinones was synthesized via a “one-pot” three component Biginelli reaction using different aldehydes in combination with β-dicarbonyl compounds and urea. Selected 2-thiooxo and 2-imino analogs were also obtained with the Biginelli reaction from thiourea and guanidine hydrochloride, respectively. The products were screened in vitro for their β-secretase inhibitory activity. The majority of the compounds resulted to be active, with IC50 in the range 100 nM–50 μM.
4-Alkyl-3,4-dihydropyrimidin-2(1 H)-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(1 H)-ones leads to 1-methyl derivatives.