Reaction of 2-aminothiazole with the N,N-dialkyl or (N-alkyl, N-phenyl) ethoxycarbonylacetamide/POCl3 reactant (I), in refluxing 1,2-dichloroethane, yielded the corresponding N,N-disubstituted 5-amino-7H-thiazolo[3,2-a]pyrimidin-7-ones (VII) along with lower quantities of isomeric N,N-disubstituted 7-amino-5H-thiazolo[3,2-a]pyrimidin-5-ones (VIII). Structures attributed to isomeric compounds (VII) and (VIII) were supported both by spectroscopic and chemical evidences. Some compounds (VII) were submitted to pharmacological investigation and results are described: only (N-alkyl, N-phenyl)derivatives (VII f,g) showed a significant, even if mild, activity as peripheral analgesics.