Synthesis of 2-chloro-N-methylpyrimidin-4-amine (18): 2,4-dichloropyrimidine (5.0 g, 33.79 mmol) was dissolved in anhydrous THF (50 mL), and a THF solution of 2.0 M methylamine (42.2 mL, 84.48 mmol) was slowly added at -40 °C. The reaction mixture was stirred at 0 °C for 4 hours. After completion of the reaction, the mixture was partitioned between CHCl3/2-propanol (4:1) and water. The organic layer was dried over anhydrous sodium sulfate, filtered through a CELITE pad and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: 100% dichloromethane) to afford 2-chloro-N-methylpyrimidin-4-amine (2.8 g, 58% yield) as a white solid. Retention time (Rt) = 1.15 min; 1H NMR (600 MHz, DMSO-d6) δ 8.02 (s, 1H), 6.22 (m, 1H), 2.86 (d, J=4.8 Hz, 3H) ppm; mass spectrum (MS) m/z: 144.12 [M+1].
