2-Amino-6-methyl-4-propyl-[1,2,4]triazolo[1,5-a]pyrimidin-5-one

27287-73-6

106-94-5

27277-00-5

2-Amino-6-methyl-[1,2,4]triazolo[1,5-a]pyrimidin-5-one (165 g, 1 mol) and bromopropane (184 g, 1.5 mol) were added to the reaction apparatus, followed by triethylamine (101 g, 1 mol) and chloroform (900 mL). The reaction mixture was heated to 65 °C and maintained at this temperature for 6 hours. The progress of the reaction was monitored by HPLC until the amount of 2-amino-6-methyl-[1,2,4]triazolo[1,5-a]pyrimidin-5-one was less than 0.5%. After completion of the reaction, the chloroform was recovered by distillation at 50 °C. Ethyl acetate (830 mL) and water (330 mL) were added to the residue and the organic phase was separated by stirring. After distillation to remove some of the ethyl acetate (~500mL), the remaining solution was crystallized. The crystals were collected by filtration and washed with water until the wash solution was neutral. Finally, dried to constant weight at 70 °C to afford 2-amino-6-methyl-4-propyl-[1,2,4]triazolo[1,5-a]pyrimidin-5(4H)-one (176 g, 85% yield, 99% purity).