Hydrochloric Acid → 6-hydroxy-2,4-dihydro-1H-3,1-benzoxazine-2,4-dione

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-hydroxyanthranilic acid (46.0 g, 300 mmol) in p-dioxane was added 1.93 M phosgene in toluene (186 mL, 360 mmol) and the resulting mixture stirred for 30 min. The mixture was heated at 65° C. for 4 h. After cooling, 1 N aqueous hydrochloric acid (150 mL) was added and the mixture stirred vigorously. The resulting precipitate was filtered and vacuum dried at 70° C./0.1 mm for 14 h to give 40.7 g (76%) of the title compound as a gray solid.

Provenance & Evidence