3-Chloroperoxybenozic acid (2.4 g, 50% pure, 7.0 mmol) was added to a mixture of [7-bromo-1-(tetrahydro-2H-pyran-4-ylmethyl)-1H-imidazo[4,5-c]quinolin-2-yl]methyl acetate (2.3 g, 5.4 mmol) and chloroform (27 mL) at ambient temperature. The reaction was stirred at this temperature for 18 hours. Saturated aqueous sodium bicarbonate (50 mL) and water (50 mL) were then added to the reaction and the layers were separated. The aqueous layer was extracted with additional dichloromethane. The organic layers were combined, dried over sodium sulfate, and concentrated under reduced pressure to a dark oil. This oil was dissolved in methanol (27 mL) and to this solution was added 15 M ammonium hydroxide (3.6 mL, 54 mmol) and benzene sulfonyl chloride (2.9 mL, 23 mmol). The resulting reaction mixture was stirred at ambient temperature for 2 hours before adding additional 15 M ammonium hydroxide (3.6 mL, 54 mmol) and benzene sulfonyl chloride (2.9 mL, 23 mmol). The reaction was stirred 18 hours. The reaction was then concentrated under reduced pressure and diluted with saturated aqueous sodium bicarbonate and chloroform. A suspension resulted that was filtered to afford a solid that was stirred with saturated aqueous sodium bicarbonate and filtered to give 1.1 g of [4-amino-7-bromo-1-(tetrahydro-2H-pyran-4-ylmethyl)-1H-imidazo[4,5-c]quinolin-2-yl]methanol as a white solid.
