3-Naphthylcarbonyl-5,5-diphenylimidazolidine-2,4-dione (200 mg) was dissolved in DMF (2 mL), benzyl bromide (45 mg) was added, and potassium carbonate (36 mg) was further added. The reaction solution was stirred at room temperature overnight. Ethyl acetate (100 mL) was added to the reaction solution, and the solution was washed with 1N hydrochloric acid, an aqueous saturated sodium bicarbonate solution and a saturated brine in turn. After the solution was dried over anhydrous magnesium sulfate, and the solvent was distilled off. The resulting residue was recrystallized from IPE to obtain 55 mg of white crystals.
