Ethyl viologen dibromide (0.069 g, 0.18 mmol), potassium carbonate (12.76 g, 92 mmol) in water (55mL), and sodium hydrosulfite (11.25 g, 65 mmol) in water (55mL) were added sequentially to a solution of tert-butyl{4-[(7-bromo-3-nitroquinolin-4-ylamino)methyl]benzyl}carbamate (9.0 g, 18.5 mmol) in dichloromethane (110 mL). The resulting biphasic mixture was stirred for 20 hours. The reaction was diluted with water (600 mL) and dichloromethane (500 mL). The layers were separated and the aqueous fraction was extracted with dichloromethane. The organic fractions were combined and washed sequentially with water and saturated aqueous sodium chloride. The organic fraction was dried over sodium sulfate, filtered, and concentrated under reduced pressure to yield 8.5 g of tert-butyl{4-[(3-amino-7-bromoquinolin-4-ylamino)methyl]benzyl}carbamate as a yellow-brown amorphous solid.
