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

We investigated a two-step approach for the easy and efficient synthesis of 1H-benzo[d][1,3]oxazine-2,4-diones starting from 2-aminobenzoic acids, using the urethane type fluorenylmethyloxycarbonyl (Fmoc), benzyloxycarbonyl (Cbz) and ethyloxycarbonyl (EtOCO) groups as the source of carbonyloxy group, and thionyl chloride to promote activation, cyclization and 1H-benzo[d][1,3]oxazine-2,4-diones formation.