One of the most important features in 4H-3,1-benzoxazinones chemistry is their use as key starting materials for further transformations in design and synthesis of biologically active compound [1,2]. 2,4(1H,3H)-Quinazolinediones and their derivatives are versatile intermediates in the synthesis of heterocycles with high pharmacological [3] and biological [4] activities. Owing to the potent activity of quinazoline-2,4-diones, considerable attention has been focused on their synthesis [5]. Herein, a practical and convenient protocol for the one-pot synthesis of the title compounds is described. The reaction of 2-ethoxycarbonylbenzoxazin-4-ones 1 with KOCN and acetic acid in DMF leads to the desired compounds quinazolin-2,4-diones 2. Good to high yields of 2 are obtained under mild reaction conditions with easy work-up.
