Imidazo[1,2-a]pyrimidine-2-carboxylic acid ethyl ester

109-12-6

70-23-5

64951-07-1

64951-06-0

The reaction mixture was heated to 75 °C and maintained for 16 hours using 2-aminopyrimidine (5 g, 52.6 mmol) and ethyl 3-bromopyruvate (90%, 7.35 mL, 52.6 mmol) dissolved in ethanol (80 mL). Upon completion of the reaction, the solvent was removed by concentration under reduced pressure. Subsequently, the reaction mixture was diluted with dichloromethane (CH2Cl2) and saturated aqueous sodium bicarbonate (NaHCO3). The organic layer was washed twice with saturated aqueous NaHCO3 and the aqueous layer was extracted three times with CH2Cl2. The organic layers were combined, dried with anhydrous magnesium sulfate (MgSO4) and concentrated again under reduced pressure. The brown oil obtained was suspended in cold CH2Cl2 and filtered, and the filter cake was washed with cold CH2Cl2 to give ethyl imidazo[1,2-a]pyrimidine-2-carboxylate (3 g, 30%) as a light yellow oil. The mother liquor contained a mixture of ethyl imidazo[1,2-a]pyrimidine-2-carboxylate and ethyl imidazo[1,2-a]pyrimidine-3-carboxylate (6 g, 60%) as a black oil. The mixture was first purified by silica gel column chromatography and then recrystallized from ethyl acetate (EtOAc) to give ethyl imidazo[1,2-a]pyrimidine-3-carboxylate (2 g, 20%).