Synthesis of 3-phenyl-2H-1,4-benzoxazin-2-one. Revision of some structural assignments

The reported synthesis of 3-phcnyl-2H-1,4-benzoxazin-2-one (II) via brominution of o-acel-amidophenyl phcnaeyl ether (Scheme) leads in lael to the 7-bromo-3-phenyl-2H-1,4-benzoxazin-2-ol (VIII). The structure of the other synthetic intermediates is also revised and a one-step synthesis of the lactone II is reported hy condensation of methyl phenylglyoxalale and o-amino-phenol.