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

Participants

Reaction Steps

To a suspension of 5-hydroxyanthranilic acid (15.3 g, 100 mmol) in THF (400 mL) at 0° C. was added triphosgene (10.1 g, 34 mmol). The resultant mixture was stirred for 5 min at 0° C. and then allowed to warm to room temperature over 6 h. The reaction mixture was cooled at 0° C. overnight and the resultant gray precipitate collected by filtration to afford 6-hydroxy-1H-benzo[d][1,3]oxazine-2,4-dione (9.8 g, 55 mmol, 55%). The filtrate was concentrated in vacuo, the resultant solid triturated with diethyl ether and collected by filtration to afford additional product (7.3 g, 41 mmol, 41%).

Provenance & Evidence