4,6-Dichloro-5-methylpyrimidine (Sigma-Aldrich No. 595446, 5 g, 30.70 mmol) was used as starting material and dissolved in a methanol solution of 7 M ammonia (15 ml, 105 mmol). The reaction mixture was placed in a sealed vial and the reaction was stirred at 140 °C for 40 min. After completion of the reaction, the resulting white suspension was poured into a mixture of water (300 ml) and ethyl acetate (600 ml), shaken well and left to stratify. The aqueous phase was separated and extracted with ethyl acetate (3 x 600 ml). The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford the target compound 6-chloro-5-methyl-4-pyrimidinamine (3.10 g, 20.73 mmol, 68% yield) as a white solid. The product was analyzed by UPLC (retention time: 0.41 min) and the mass spectrum showed major peaks at m/z 144 ([M+H]+, 100%) and m/z 146 ([M+H]+, 33%), which was in accordance with the theoretical molecular weight of 143 (C5H6ClN3).1H NMR (400 MHz, DMSO-d6) δ (ppm): 8.06 (s, 1H) , 7.09 (bs, 2H), 2.07 (s, 3H).
