General procedure for the synthesis of 2-amino-3-fluoro-5-chloropyridine from 2-amino-3-fluoro-5-chloropyridine: 2-amino-3-fluoro-5-chloropyridine (50 g, 0.341 mol) and methanol (600 mL) were added to a 1000 mL single-necked round-bottomed flask, and stirred until completely dissolved. Ammonia (50 mL) and Pd/C catalyst (2.5 g, 23.5 mmol) were then added. The catalytic hydrogenation reaction was carried out under hydrogen atmosphere until the reaction was complete. After completion of the reaction, the Pd/C catalyst was removed by filtration and the filter cake was washed with methanol. The filtrate and washings were combined and concentrated under reduced pressure to give a white solid crude. The crude was dissolved in water (200 mL x 4) and extracted with ethyl acetate. The organic layer was collected, dried with anhydrous sodium sulfate and concentrated under reduced pressure. Finally, the concentrate was pulped with a small amount of petroleum ether and filtered to give 34.50 g of white crystal product in 90.20% yield.
