The general procedure for the synthesis of 3-amino-6-chloropyridazine from 3,6-dichloropyridazine was as follows: 3,6-dichloropyridazine (107,500 mg, 3.36 mmol) was slowly added to 2.0 M ammonia methanol solution (NH3 in MeOH, 17 mL, 33.6 mmol). The reaction mixture was heated at 130 °C for 96 h and subsequently cooled to room temperature. After the reaction was completed, water was carefully added. The organic compounds were extracted with ethyl acetate and the combined organic phases were washed with saturated aqueous sodium chloride solution. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by column chromatography to afford the target compound 3-amino-6-chloropyridazine (108d, 265 mg, 61% yield) as a white solid. The structure of the product was confirmed by 1H NMR (400 MHz, CD3OD) δ 6.95 (d, J = 9.6 Hz, 1H), 7.34 (d, J = 9.2 Hz, 1H) and 13C NMR (100 MHz, CD3OD) δ 119.8, 131.1, 147.1, 161.5.
