[Synthesis]
The general procedure for the synthesis of 4-amino-6-bromoquinoline from 6-bromo-4-chloroquinoline was as follows: 6-bromo-4-chloroquinoline (500 mg, 2.1 mmol), acetamide (2.438 g, 41.3 mmol), and potassium carbonate (1.449 g, 10.5 mmol) were added to a reaction flask fitted with a magnetic stirrer. The reaction mixture was heated to 180 °C and maintained at this temperature for 5 hours. After completion of the reaction, the mixture was cooled to room temperature and diluted with water (50 mL). The aqueous phase was extracted with ethyl acetate (20 mL × 3), the organic phases were combined and dried over anhydrous sodium sulfate. The desiccant was removed by filtration and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol = 20:1) to afford the target product 6-bromoquinolin-4-amine (198 mg, 43% yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6) and LC-MS (ESI) to confirm its structure.1H NMR (400 MHz, DMSO-d6) δ 8.46 (d, J = 2.2 Hz, 1H), 8.25 (d, J = 7.2 Hz, 1H), 7.95 (dd, J = 8.9, 2.3 Hz, 1H), 7.69 (d, J = 8.9, 2.3 Hz, 1H), 7.69 (d, J = 8.9, 2.3 Hz, 1H), 7.95 (dd, J = 8.9, 2.3 Hz, 2.3 Hz, 1H) 7.69 (d, J = 8.9 Hz, 1H), 7.12 (d, J = 7.2 Hz, 1H), 5.64 (s, 2H). LC-MS (ESI) m/z = 223.1, 225.1 (M + H, M + 2 + H). |