The general procedure for the synthesis of 4-amino-6-methylpyrimidine from 3-aminobut-2-enenenitrile and trimethyl orthoformate was as follows: in a 10 mL stainless steel pressure-resistant vessel, 1.0 g (11.7 mmol, 96% purity) of 3-aminobut-2-enenitrile, 2.48 g (23.4 mmol) of trimethyl orthoformate, and 1.42 g (17.5 mmol) of a 21 wt% ammonia-methanol solution. The mixture was stirred and reacted at 130°C for 15 hours. Upon completion of the reaction, the reaction mixture was concentrated under reduced pressure. To the concentrate was added 10 mL of isopropanol and 660 mg of activated charcoal, stirred at 90 °C for 1 h and filtered. To the filtrate, 660 mg of activated carbon was added again and stirred at 90°C for 1 hour. After filtration, the filtrate was concentrated and 1.8 mL of isopropanol and 3 mL of toluene were added to the concentrate, and the mixture was heated to 90°C and then gradually cooled and stirred at -5°C for 1 hour. The precipitated solid was collected by filtration and dried under reduced pressure to give 326 mg (26% isolated yield, 99.5% purity, GC area percentage) of 6-methyl-4-aminopyrimidine as white crystals.The physical properties of 6-methyl-4-aminopyrimidine were as follows: 1H-NMR (DMSO-d6, δ/ppm): 2.17 (3H, s), 6.25 (1H, s) , 6.65 (2H, brs), 8.21 (1H, s); CI-MS (m/e): 110 (M+1).
