[Synthesis]
General procedure for the synthesis of 7-bromoquinolin-3-ol from 7-bromo-3-methoxyquinoline: 7-bromo-3-methoxyquinoline (1.1 g, 4.62 mmol) was dissolved in acetic acid (20 mL), 48% hydrobromic acid (5.0 mL, 92 mmol) was added, and the reaction was carried out by refluxing the mixture at 120 °C for 4 days. The progress of the reaction was monitored by LCMS, showing a conversion of about 50%. Upon completion of the reaction, the mixture was poured into ice water and the pH was adjusted to alkaline with ammonia. Subsequently, the aqueous phase was extracted with ether (3 x 20 mL), and the organic phases were combined and concentrated. The residue was purified by fast column chromatography (eluent: 10-50% ethyl acetate/hexane) to afford the target product 7-bromoquinolin-3-ol (500 mg, 2.232 mmol, 48% yield) as a tan solid. The product was characterized by 1H NMR (400 MHz, DMSO-d6), chemical shift δ (ppm): 7.55 (d, J=2.53 Hz, 1H), 7.63 (dd, J=8.59,2.02 Hz, 1H), 7.80 (d, J=8.84 Hz, 1H), 8.10 (d, J=1.77 Hz, 1H), 8.60 (d , J=2.78Hz, 1H), 10.51 (s, 1H). |