405230-93-5

405230-90-2

405230-93-5

General procedure for the synthesis of 2-chloro-3,4-diamino-5-fluoropyridine from 2-chloro-5-fluoro-3-nitropyridin-4-amine: a mixture of 4-amino-2-chloro-5-fluoro-3-nitropyridine (0.45 g, 2.3 mmol) and nickel ruanide (0.6 g) in anhydrous ethanol (10 mL) was placed in the Parr hydrogenation apparatus at 36 rpm The hydrogenation reaction was carried out. The progress of the reaction was monitored by thin layer chromatography (TLC) until the starting material completely disappeared. Upon completion of the reaction, the catalyst was removed by filtration and carefully washed with ethanol (2 x 10 mL). The filtrates were combined and the solvent was removed by vacuum evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: dichloromethane/ethanol, 20:1, v/v) to afford the target compound 2-chloro-3,4-diamino-5-fluoropyridine (0.26 g, yield: 68%). The structure of the product was confirmed by 1H NMR (DMSO-d6, 400 MHz), δ 7.45 (d, J = 2.0 Hz, 1H), 5.80 (br s, 2H), 4.98 (br s, 2H).