Abstract The condensation product of anthranilic acid with phthalylchloride, wrongly described as “anthranilic acid phthalidene iminoether ester” was shown to be 2-[2- carboxyphenyl]-3, 1-benzoxazin-4-one (4) by IR-spectra and chemical reactions. Further derivatives of anthranilic acid and N-Methyl-spiro-[2 H-3, 1-benzoxazin-2.1′-phthalan]-4, 3′-dione, a derivative of 1, are described.
