Step A: Synthesis of 4,5-dimethylpyrimidin-2-amine
4-Chloro-5,6-dimethylpyrimidin-2-amine (0.35 g, 2.22 mmol) was dissolved in a methanolic solution of 2M ammonia (100 mL) and after the system was displaced three times with nitrogen, palladium carbon catalyst (0.035 g, 0.33 mmol) was added. The system was again replaced with nitrogen, followed by the hydrogenation reaction at 1 atmosphere and room temperature for 18 hours. Upon completion of the reaction, the reaction system was displaced with nitrogen and the reaction mixture was filtered through diatomaceous earth and the diatomaceous earth pad was washed with methanol. The filtrates were combined and concentrated to dryness under reduced pressure to afford the crude product 4,5-dimethylpyrimidin-2-amine (0.35 g, 2.56 mmol, 90% yield), which could be used in subsequent reactions without further purification.
The product was characterized as follows:
1H NMR (400 MHz, DMSO-d6) δ ppm: 7.89 (1H, s), 6.19 (2H, s), 2.18 (3H, s), 1.99 (3H, s).
MS (LC/MS) retention time (R.T.) = 0.56 min; [M + H]+ = 124.20.
