The general procedure for the synthesis of 5-bromo-4,6-dichloropyrimidin-2-amine from 2-amino-4,6-dichloropyrimidine was as follows: over a period of 20 min, bromine (0.85 mL, 0.0166 mol) was slowly added dropwise to a stirring 1:1 mixture of 2-amino-4,6-dichloropyrimidine (CAS # 56-05-3, 1.70 g, 0.01037 mol) and sodium carbonate ( 1.00 g, 0.01244 mol) in a 1:1 methanol/water (30 mL) mixture and the reaction was carried out at room temperature. Ten minutes after completion of the dropwise addition, additional sodium carbonate (0.78 g, 0.0093 mol) was added to the reaction mixture. The reaction mixture was continued to be stirred at room temperature for 42 hours. Upon completion of the reaction, the reaction mixture was diluted with aqueous sodium bicarbonate to precipitate 5-bromo-4,6-dichloropyrimidin-2-amine precipitate which was collected by filtration and washed with distilled water. Vacuum drying gave 2.11 g of white solid in 83.7% yield. The product was characterized by 1H NMR (300 MHz, d6-DMSO): δ 7.67 (s, 1H), 7.70 (s, 1H). Mass spectrum (DC1-NH3) showed: m/z = 241 (M + H)+, m/z = 258 (M + NH4)+.
