2-Bromo-5-nitropyridin-4-amine (300.0 mg, 2.48 mmol) was used as starting material, which was added to acetic acid together with iron powder (300.0 mg, 5.37 mmol). The reaction mixture was stirred at 75 °C for 4 h and subsequently cooled to room temperature. The reaction mixture was filtered through diatomaceous earth and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography with an eluent ratio of hexane: ethyl acetate = 50:50. The fraction containing the target product was collected and concentrated under reduced pressure to afford 6-bromopyridine-3,4-diamine (200.0 mg, 78% yield) as a brown solid.1H-NMR (400 MHz, DMSO-d6) data were as follows: δ 7.39 (s, 1H), 6.42 (s, 1H), 5.74 (brs, 2H), 4.66 (brs, 2H).
