7-Bromo-2-ethoxymethyl-1-(3-isopropoxypropyl)-1H-imidazo[4,5-c]quinoline (20 g) was dissolved in chloroform (400 mL). 3-Chloroperoxybenzoic acid (60% pure, 17.1 g) was added in 2 g portions over a 5 minute period and the reaction was stirred for 1 hour. Ammonium hydroxide (300 mL) was added and the mixture was cooled to 5° C. with an ice/water bath. p-Toluenesulfonyl chloride (9.4 g) was added at the rate of 1 g/min to minimize gas evolution. After stirring for 16 hours, the layers were separated and the aqueous fraction was extracted with chloroform. The combined organic fractions were sequentially washed with 5% aqueous sodium bicarbonate, water and brine; dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography on silica gel. The polar component of the eluent was chloroform:methanol:ammonium hydroxide 80:18:2 (CMA). The purification was carried out eluting with chloroform:CMA in a gradient from 98:2 to 88:12. The material recovered from the column was recrystallized from acetonitrile to yield 7.0 g of 7-bromo-2-ethoxymethyl-1-(3-isopropoxypropyl)-1H-imidazo[4,5-c]quinolin-4-amine as a tan granular powder.
