207 mg of 4-(3-benzoylaminophenyl)-6,7-dimethoxy-2-methylaminoquinazoline obtained in Example 1 was dissolved in 5 ml tetrahydrofuran, and 0.667 ml of 1.5 M lithium diisopropylamide in hexane was added dropwise thereto at −70° C. After the dropwise addition, the mixture was stirred at −70° C. for 30 minutes, and then 284 mg of methyl iodide was added thereto. The mixture was returned to room temperature and further stirred for 1 hour. After ethyl acetate was added thereto, the mixture was washed with water twice and with brine, and then dried over anhydrous magnesium sulfate. The solvent was evaporated, and the crude product was purified and separated by silica gel column chromatography (hexane:ethyl acetate=1:3). The product was recrystallized from hexane-ethyl acetate to give 75 mg of the title compound as pale yellow crystals.
