2-Amino-6-methyl-5-oxo-4,5-dihydro-1,2,4-triazolo[1,5-a]pyrimidine was synthesized from 2-bromopropionic acid methyl ester, α,α-dichloromethyl methyl ether and guanazole via condensation and cyclization reactions. An attempt to improve its solubility in organic solvents was achieved by the nucleophilic substitution with 1-bromobutane to give 2-amino-4-n-butyl-6-methyl-5-oxo-4,5-dihydro-1,2,4-triazolo [1,5-a]pyrimidine in a good yield. Finally, a series of 2-(substituted amino)-4-n-butyl-6-methyl-5-oxo-4,5- dihy-dro-1,2,4-triazolo[1,5-a]pyrimidines having potential emetic activity were obtained by Ugi multi-component reactions. The structures of these compounds were confirmed by MS, ¹H NMR and ¹³C NMR spectra and elemental analysis.

Key words: nucleophilic substitution, 1,2,4-triazolo[1,5-a]pyrimidine, Ugi multi-component reaction