The general procedure for the synthesis of methyl 5-aminopyrimidine-2-carboxylate from methanol and 5-aminopyrimidine-2-carboxylic acid was as follows: 5-aminopyrimidine-2-carboxylic acid (Goldenbridge Pharma, Inc.; 5.70 g, 41.0 mmol) was suspended in methanol (120 mL) and cooled in an ice water bath. Subsequently, thionyl chloride (8.97 mL, 123 mmol) was added slowly and dropwise. The resulting suspension was heated and refluxed for 20 h. After completion of the reaction, the mixture was concentrated to give a yellow solid. The solid was dissolved in saturated aqueous sodium bicarbonate (60 mL) and extracted with ethyl acetate using a Gregar extractor. The extract was concentrated to give methyl 5-aminopyrimidine-2-carboxylate (4.26 g, 68% yield) as an off-white solid.1H NMR (400 MHz, CDCl3): δ 8.32 (s, 2H), 4.35 (br s, 2H), 4.02 (s, 3H).
