Triphosgene → 5-Fluoroisatoic anhydride

Participants

Reaction Steps

In a separate preparation, 2-amino-5-fluorobenzoic acid (15 g, 97 mmol) was dissolved in tetrahydrofuran (250 mL) and triphosgene (10.04 g, 33.8 mmol) was added portion-wise. A thick white precipitate formed with a small exotherm. The slurry gradually became easier to stir and was left stirring at room temperature for 16 h. The mixture was filtered to provide a white solid which was rinsed with diethyl ether then dried at 50° C. in a vacuum over to give 6-fluoro-1H-benzo[d][1,3]oxazine-2,4-dione (14.1 g, 78 mmol). The 6-fluoro-1H-benzo[d][1,3]oxazine-2,4-dione may be converted to a 7-fluoro-1-(4-methoxybenzyl)-3,4-dihydro-1H-benzo[e][1,4]diazepine-2,5-dione using the procedures described in Example 1.

Provenance & Evidence