4-N-(N,N-dimethylaminomethylene)-1-methylcytosine (1.0 g, 5.5 mmol) was added to a 100 mL round bottom flask equipped with a magnetic stirrer along with an ethanol solution (50 mL) containing 30% methylamine. The reaction mixture was stirred at room temperature for 12 hours. Upon completion of the reaction, the precipitated white solid was collected by filtration and purified by recrystallization using ethanol-water solvent mixture. 4-Amino-1-methylpyrimidin-2(1H)-one was finally obtained as a white solid (0.61 g, 88% yield). The structure of the product was analyzed by 1H NMR (400 MHz, DMSO-d6): δ3.31 (s, 3H), 5.59 (d, 1H), 6.91 (br, 2H), 7.54 (d, 1H); 13C NMR (100 MHz, DMSO-d6): δ6.6, 92.9, 146.6, 156.3, 166.1; mass spectrometry (ES+) ) analysis: calculated value C5H7N3O+ (M+H+) 126.0662, measured value 126.0804 confirmed.
