Water → 7-bromo-2H,3H,4H-pyrido(3,2-b)(1,4)oxazin-3-one

Reaction equation

[O:1]1[CH2:6][C:5](=[O:7])[NH:4][C:3]2[N:8]=[CH:9][CH:10]=[CH:11][C:2]1=2.C1C(=O)N([Br:19])C(=O)C1.O>CN(C=O)C>[Br:19][C:10]1[CH:9]=[N:8][C:3]2[NH:4][C:5](=[O:7])[CH2:6][O:1][C:2]=2[CH:11]=1

Participants

Procedure

To a solution of 2H-pyrido[3,2-b][1,4]oxazin-3-one (0.75 g, 5 mmol) in DMF (18 mL) was slowly added NBS (1.07 g, 6 mmol) under N2. The mixture was stirred at rt for 16 h. HPLC indicated 75% conversion. More NBS (0.53 g, 3 mmol) was added and the mixture was stirred for another 24 h. Water (5 mL) was added and the reaction flask was chilled. The white solid which separated was filtered and washed with EtOAc, H2O, Et2O, and dried under vacuum in the presence of PBS and then used directly in the next step (687 mg, 60%).