The methods described in Parts A-I of Example 2 were followed using 3-benzyloxyaniline in lieu of 4-benzyloxyaniline and methoxypropionyl chloride in lieu of ethoxyacetyl chloride. 2-(2-Methoxyethyl)-1-propyl-1H-imidazo[4,5-c]quinolin-7-ol (2.0 g, 7.0 mmol), 4-(dimethylamino)pyridine (0.085 g, 0.70 mmol), and tetrahydrofuran (70 mL) were combined, and the mixture was cooled to 7° C. with an ice/water bath. Isopropyl isocyanate (0.689 mL, 7.01 mmol) was added dropwise to the mixture. After 20 minutes the cooling bath was removed and the reaction was stirred for an additional 24 hours. Analysis by HPLC indicated that no product had formed. Di-butyltin dilaurate (1 drop) was added, and the reaction was stirred at ambient temperature for 2.5 hours and then heated at reflux for 48 hours. The solvent was evaporated under reduced pressure, and the residue was dissolved in dichloromethane. The organic fraction was washed sequentially with water and brine, dried over magnesium sulfate, filtered, and concentrated under reduced pressure. Purification by column chromatography on silica gel (eluting with a chloroform:methanol:ammonium hydroxide gradient) provided 1.97 g of 2-(2-methoxyethyl)-1-propyl-1H-imidazo[4,5-c]quinolin-7-yl isopropylcarbamate as a white solid.
