15862-31-4

896160-69-3

General procedure for the synthesis of 3-bromo-2,5-diaminopyridine from 2-amino-3-bromo-5-nitropyridine: 2-amino-3-bromo-5-nitropyridine was suspended in methanol (6.0 mL) in a 30 mL flask. A solution of ammonium chloride (5.0 eq.) in water (6.0 mL) was added, followed by iron powder (5.0 eq.). The suspension was stirred and reacted at 80°C for 2 hours. Upon completion of the reaction, the mixture was filtered while hot (~50°C). The filtrate was concentrated and purified by column chromatography (using KANTO 60N silica gel with an eluent ratio of dichloromethane/methanol = 97/3 to 92/8) to afford the target product, 3-bromo-2,5-diaminopyridine solid.