Investigation for the easy and efficient synthesis of 1H-benzo[d][1,3]oxazine-2,4-diones

We report the synthesis of 1H-benzo[d][1,3]oxazine-2,4-diones from 2-aminobenzoic acids, using fluorenylmethyloxycarbonyl (Fmoc), benzyloxycarbonyl (Cbz) and ethyloxycarbonyl (EtOCO) groups as the source of carbonyloxy group, and thionyl chloride.