N-bromobutanimide → 7-Bromo-5-fluoro-2,3-dihydro-1,4-benzodioxine
Reaction equation
[F:1][C:2]1[C:11]2[O:10][CH2:9][CH2:8][O:7][C:6]=2[CH:5]=[CH:4][CH:3]=1.[Br:12]N1C(=O)CCC1=O>CO>[Br:12][C:4]1[CH:3]=[C:2]([F:1])[C:11]2[O:10][CH2:9][CH2:8][O:7][C:6]=2[CH:5]=1Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
A solution of 5-fluoro-2,3-dihydrobenzo[b][1,4]dioxine (1.54 g, 10.0 mmol) and 1-bromopyrrolidine-2,5-dione (1.8 g, 10 mmol) in methanol (20 mL) was heated at reflux for 0.5 h, allowed to cool to ambient temperature and concentrated in vacuo. The residue was taken up in dichloromethane (50 mL) and washed with water (50 mL). The organic phase was dried over magnesium sulfate, filtered and concentrated in vacuo. Purification of the residue by column chromatography eluted with a 0% to 30% gradient of ethyl acetate in hexanes afforded 7-bromo-5-fluoro-2,3-dihydrobenzo[b][1,4]dioxine (2.04 g, 87%) as a colorless solid: MS (ES+) m/z 233.6 (M+1).