30 ml of tetrahydrofuran, 30 ml of ethanol and 14 ml of a 1N aqueous solution of sodium hydroxide were added to 1.0 g of 2-(4-ethoxycarbonylpiperidino)-4-(3-chloro-4-methoxybenzyl)amino-6-cyanoquinazoline. The obtained mixture was stirred at room temperature for 16 hours and neutralized with 1N hydrochloric acid, followed by the addition of 100 ml of water. The crystals thus precipitated were recovered by filtration and recrystallized from tetrahydrofuran/ethanol/water to give 860 mg of the title compound.
