4H-3,1-benzoxazin-4-ones thermal cyclodehydration of N-benzoylanthranilic acid

Water is split out to form 2-phenyl-4H-3,1-benzoxazin-4-one when N-benzoylanthranilic acid is heated. A mass spectrometric study of O¹⁸-labeled N-benzoylanthranilic acid and the product of its thermal cyclodehydration showed that the oxygen atoms of the carboxyl and benzoyl groups participate equally probably in splitting out of water.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 614–615, May, 1977.