To a solution of the hydrochloride salt of tert-butyl 2-({2-chloro-3-[(ethoxyacetyl)amino]quinolin-4-yl}amino)ethylcarbamate (2.50 g, 5.44 mmol) in 9:1 ethanol/water (50 mL) was added a solution of potassium carbonate (1.12 g, 8.16 mmol) in water (5 mL). The solution was heated to 50° C. for five hours. The solution was concentrated under reduced pressure and the residue was partitioned between saturated aqueous sodium bicarbonate and dichloromethane. The aqueous layer was extracted with two additional portions of dichloromethane. The combined organic layers were washed with brine, dried over magnesium sulfate, filtered, and concentrated to a pale yellow solid that was purified by flash chromatography (silica gel, gradient elution from 1:1 to 4:1 ethyl acetate/hexane) to afford the tert-butyl 2-(4-chloro-2-ethoxymethyl-1H-imidazo[4,5-c]quinolin-1-yl]ethylcarbamate as a white solid (1.55 g).
