The general procedure for the synthesis of 2,5-dichloro-N-(5-methyl-1H-pyrazol-3-yl)-4-aminopyrimidine from 3-amino-5-methyl-1H-pyrazole and 2,4,5-trichloropyrimidine was as follows: to a solution of 5-methyl-1H-pyrazol-3-amine (4.00 g, 41.2 mmol) in anhydrous ethanol (100 mL) was added triethylamine (12.51 g (123.6 mmol) and 2,4,5-trichloropyrimidine (7.56 g, 41.2 mmol). The reaction mixture was stirred at room temperature for 16 h and subsequently concentrated under vacuum. The residue was purified by silica gel column chromatography (petroleum ether/ethyl acetate, v/v = 1/1) to afford the target compound 2,5-dichloro-N-(5-methyl-1H-pyrazol-3-yl)-4-aminopyrimidine as a light yellow solid (9.00 g, 89.5% yield). Mass spectrum (ESI, positive ion mode) m/z: 244.1 [M + H]+; NMR hydrogen spectrum (600 MHz, DMSO-d6) δ (ppm): 12.32 (broad single peak, 1H), 9.70 (single peak, 1H), 8.33 (single peak, 1H), 6.28 (single peak, 1H), 2.25 (single peak, 3H).
