a) Synthesis of 3-aminoquinolin-4-ol
In a 100 mL round bottom flask, 4-hydroxy-3-nitroquinoline (500 mg, 2.629 mmol) was dissolved in methanol (50 mL) and 10% palladium/activated carbon catalyst (1.2 g, 10 wt%) was added. The reaction mixture was stirred at room temperature and under hydrogen atmosphere for 3 hours. Upon completion of the reaction, the catalyst was removed by filtration through a diatomaceous earth pad, and the filtrate was concentrated under reduced pressure to give the brown liquid-like product 3-aminoquinolin-4-ol (445 mg, quantitative yield). The structure of the product was confirmed by 1H-NMR (DMSO-d6, 300 MHz): δ= 11.50 (br s, 1H), 8.09 (d, J = 8.4 Hz, 1H), 7.48 (s, 1H), 7.47 (m, 2H), 7.14-7.20 (m, 1H), 4.38 (br s, 2H).
