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The general procedure for the synthesis of 4-amino-2-(methylthio)pyrimidine-5-carboxylic acid from ethyl 2-(methylthio)-4-amino-pyrimidine-5-carboxylate was as follows: ethyl 4-amino-2-methylmercaptopyrimidine-5-carboxylate (1.5 g, 7 mmol) was suspended in a mixed methanol (10 mL) and water (5 mL) solution containing lithium hydroxide (340 mg, 14 mmol). solution, and the reaction was stirred at 60°C overnight. Upon completion of the reaction, the solid was collected by filtration and the filtrate was combined. The filtrate was concentrated under reduced pressure to remove the solvent. The residue was dissolved in water and the pH was adjusted with acetic acid to 5. The precipitated white solid was collected by filtration and dried under vacuum to give the target product (0.72 g, 55% yield). [0307] HPLC analysis (4 min gradient) showed retention time t R = 0.55 min; mass spectrometry analysis showed m/z 186.08 ([M + H]+).