Synthesis Method 2: Preparation of 6-chloro-8-aminoquinoline (precursor to Example Compound 4); To a stirred suspension of 6-chloro-8-nitroquinoline (Synthesis Method 1; 1.00 g, 4.79 mmol) in water (20 mL) was added acetic acid (0.82 mL, 14.3 mmol) and iron powder (1.61 g, 28.8 mmol) sequentially. The reaction mixture was heated to near reflux temperature, maintained for 1.5 h and then cooled to room temperature. Solid sodium hydroxide (0.65 g, 16.3 mmol) and ethyl acetate (30 mL) were added to the reaction system under continuous stirring. Diatomaceous earth (30 mL) was then added and the slurry was separated by filtration. The filter cake was washed with ethyl acetate. The combined filtrates were sequentially washed with aqueous sodium bicarbonate, dried over sodium sulfate and concentrated. The resulting brown viscous oil was purified by rapid chromatography on silica gel (eluent: hexane/ethyl acetate) to give 0.57 g of yellow solid product (67% yield). Product characterization data: 1H NMR (CDCl3) δ 8.71 (dd, J = 4.2, 1.5 Hz, 1H), 7.94 (dd, J = 8.3, 1.5 Hz, 1H), 7.36 (dd, J = 8.3, 4.2 Hz, 1H), 7.09 (d, J = 2.1 Hz, 1H), 6.84 (d, J = 2.1 Hz, 1H), 5.09 (br s, 2.1 Hz, 1H), 5.09 (br s, 2.1 Hz, 1H). 5.09 (br s, 2H) ppm.
