反应详情

2-Amino-3,5-difluoro-benzoic acid (2.44 g, 0.0141 mol) was dissolved in Tetrahydrofuran (100 mL). Triphosgene (4.18 g, 0.0141 mol) was dissolved in Tetrahydrofuran (10 mL) and added. The resulting solution was stirred for 4 h at rt. The reaction mixture was concentrated, and the resulting residue was sonicated in H20. The peach ppt was filtered, taken up in acetone, and was concentrated under reduced pressure. It was then azeotroped in toluene to give 6,8-Difluoro-1H-3,1-benzoxazine-2,4-dione as tan solids (2.64 g, 94%). 1H-NMR (DMSO): 12.00 (s, 1H), 7.85 (m, 1H), 7.60 (m, 1H); 19F-NMR (DMSO): −116, −125.

1. additionadded
2. concentrationThe reaction mixture was concentrated
3. customthe resulting residue was sonicated in H20
4. filtrationThe peach ppt was filtered
5. concentrationwas concentrated under reduced pressure
6. customIt was then azeotroped in toluene