Acetic anhydride (50 mL) was slowly added dropwise to a suspension of formic acid (125 mL) of 4,6-dichloro-5-aminopyrimidine (10.37 g, 164 mmol) at 0 °C. The reaction mixture was then stirred at room temperature for 2.5 hours. Upon completion of the reaction, the volatile components were removed by distillation under reduced pressure. The resulting residue was co-evaporated three times with toluene (50 mL) to completely remove the residual solvent, resulting in N-(4,6-dichloropyrimidin-5-yl)formamide as a white solid (12.1 g, quantitative yield). The product was used for subsequent reactions without further purification.1H NMR (d6-DMSO) δ 8.32 (s, 1H), 8.83 (s, 1H, CHO), 10.51 (br s, 1H, NH).
