3,1-Benzoxazin-4-one and their derivatives1,2 are versatile intermediates in the synthesis of heterocycles with high pharmacological and biological activities.3,4 Here, we report a practical and convenient synthesis of N-(4-chlorobutanoyl)-1,2-dihydro-(4H)-3,1-benzoxazin-4-ones by cyclization reaction of Schiff-bases 3 (produced by condensation reaction of anthranilic acid derivatives 1 with benzaldehyde derivatives 2 at room temperature) with 4-chlorobutanoyl chloride at room temperature (Scheme 1). The presence of Cl in the end of butanoyl chain, makes the produced benzoxazine-4-ones 4 more reactive for further reactions against nucleophiles. The structures of all synthesized compounds were determined on the basis of their spectroscopic data.
