[F:1][C:2]1[CH:10]=[CH:9][C:8]([F:11])=[C:7]2[C:3]=1[CH2:4][N:5](S(C1C=CC(C)=CC=1)(=O)=O)[CH2:6]2.C1(O)C=CC=CC=1.Br>O.C(O)(=O)CC>[F:1][C:2]1[CH:10]=[CH:9][C:8]([F:11])=[C:7]2[C:3]=1[CH2:4][NH:5][CH2:6]2A mixture of 4,7-difluoro-2-(toluene-4-sulfonyl)isoindoline (2.36 g, 7.64 mmol), phenol (2.36 g, 25.11 mmol), 48% hydrogen bromide in water (20 ml) and propionic acid (4 ml) was stirred and held at reflux for 6 hours. Upon cooling to room temperature water (50 ml) was added and the mixture extracted with diethyl ether (2×100 ml). The aqueous layer was basified by the addition of 2M sodium hydroxide and was extracted with diethyl ether (3×100 ml). The combined extracts were evaporated to dryness in vacuo to afford 4,7-difluoroisoindoline (586 mg, 50%) as a brown oil that solidified upon standing. 1H NMR (DMSO-d6) 7.06 (2H, dd), 4.12 (4H, s). MS: [M+H]+ 156.
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