190728-25-7

190728-24-6

190728-25-7

Step 2: Synthesis of 4-[(6,7-dimethoxyquinolin-4-yl)oxy]aniline (99) To a 1:1 MeOH/THF (50 mL) mixed solvent of 6,7-dimethoxy-4-(4-nitrophenoxy)quinoline (98) (0.25 g, 0.77 mmol) was added a solution of zinc powder (0.55 g, 8.4 mmol) and ammonium chloride (0.085 g, 1.6 mmol) in water (5 mL). The reaction mixture was heated to reflux for 2 hours. Upon completion of the reaction, the insoluble material was removed by diatomaceous earth filtration and the filtrate was concentrated under reduced pressure. The concentrated residue was dissolved in dichloromethane, washed sequentially with water and saturated saline, and the organic phase was dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give the crude product 99 (0.25 g, >100% yield), which can be used directly in the next reaction without further purification. Mass spectrometry (MS) data: m/z 297.1 ([M+H]+).