4H-3,1-benzoxazin-4-ones as an important class of hetrocyclic compounds have been known for more than a century. Contrary to the parent compounds 4H-3,1-benzoxazin-4-ones [1], very few synthetic routes have ever been published for N-substituted-1,2-dihydro-(4H)-3,1-benzoxazin-4- ones [2-5]. They are potential starting material for synthesis of important heterocycles such as 1,4- benzodiazepine-2,5-diones and indoxyls [6]. Here, we report a facile and convenient one-pot synthesis of the title compounds using condesation reaction of an anthranilic acid derivative 1 with an aryl aldehyde 2 and then, cyclization reaction of the produced schiff base by ethyl 2-chloro-2-oxoacetate. Good to high yields of 3 are obtained under mild reaction conditions with easy work-up.
