General procedure for the synthesis of 2-amino-5-bromophenol from 5-bromo-2-nitrophenol: 5-bromo-2-nitrophenol (0.292 g, 1.34 mmol) was dissolved in 0.5% aqueous sodium hydroxide solution (30 mL) and stirred until completely dissolved. Sodium bisulfite (2.00 g, 85% pure, 9.76 mmol) was added to the reaction system and the reaction was stirred at room temperature for 15 minutes. After completion of the reaction, the reaction mixture was slowly acidified with dilute hydrochloric acid to pH 5. Subsequently, the reaction mixture was extracted with diethyl ether (40 mL) in three portions, the organic phases were combined and dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure to give the crude product 2-amino-5-bromophenol (0.533 g, melting point 99.5-100.5 °C). The crude product was recrystallized by mixed solvent recrystallization from ether/hexane to give the pure product 2-amino-5-bromophenol (0.151 g, 0.80 mmol, 60% yield; melting point 125-127 °C (decomposition), melting point reported in the literature as 149.5-150.5 °C (Boyland, E et al., 1954)). The structure of the product was confirmed by 1H NMR (CD3CN, 500 MHz) and IR (KBr): 1H NMR δ 7.08 (bs, 1H), 6.82 (d, 1H, J=2Hz), 6.78 (dd, 1H, J=8.2Hz), 6.56 (d, 1H, J=8Hz), 4.03 (bs, 2H); IR 3496 (wide) 3377, 3298, 1598, 1502, 1431, 1269, 1210, 916, 877 cm-1.
