A solution of 3-dibenzylamino-6,7-difluoro-1H-quinazoline-2,4-dione (Example 16) (0.43 g, 1.1 mmol) in 10 mL of N,N-dimethylformamide is added to a suspension of sodium hydride (0.05 g, 1.3 mmol) in 10 mL of N,N-dimethylformamide and stirred for 30 minutes. Ethyl iodide (0.13 mL, 1.6 mmol) is added, and the mixture is stirred at 25° C. for 18 hours. The reaction is quenched with 1 mL of water and concentrated in vacuo. The residue is dissolved in chloroform, washed with water, brine, and dried over magnesium sulfate. The solution is concentrated and purified via chromatography (SiO2, CHCl3) to give 0.34 g of the title compound as a solid, mp 133-135° C., MS CI, m/z 422 (MH+).
