Synthesis of 5-Methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one in Supercritical Carbon Dioxide

Abstract

5-Methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one, an intermediate product in the synthesis of the antiviral drug Triazid®, was obtained for the first time by condensation of 3H-1,2,4-triazol-5-amine with ethyl acetoacetate in the presence of a catalytic amount of ZnCl₂ in supercritical carbon dioxide (200 bar) under solvent-free conditions. Depending on the temperature and reaction time, the conversion was 90%.