P(Br)(Br)([Br:3])=O.[F:6][C:7]1[CH:12]=[CH:11][C:10]([CH2:13][C:14]2[CH:15]=[C:16]([N+:21]([O-:23])=[O:22])[C:17](=O)[NH:18][CH:19]=2)=[CH:9][CH:8]=1.CN(C=O)C.[OH-].[Na+]>C1(C)C=CC=CC=1.O>[Br:3][C:17]1[C:16]([N+:21]([O-:23])=[O:22])=[CH:15][C:14]([CH2:13][C:10]2[CH:11]=[CH:12][C:7]([F:6])=[CH:8][CH:9]=2)=[CH:19][N:18]=1A solution of POBr3 (227 g, 0.79 mol) in toluene (900 mL) was added slowly to a stirred suspension of 5-[(4-fluorophenyl)methyl]-3-nitro-2(1H)-pyridinone (179 g, 0.72 mol) in toluene (900 mL). The mixture was heated to reflux; then cooled to rt and DMF (56 mL, 0.72 mol) was added slowly; the mixture was again heated to reflux and then allowed to cool to rt overnight. After cooling the mixture in an ice-bath, water (500 mL) was added slowly followed by dropwise addition 4 N NaOH (450 mL, 1.76 mol). All insoluble material was removed by filtration and the two liquid phases were separated. The organic layer was concentrated at reduced pressure to afford the product as a beige solid: 1H NMR (d6-DMSO) δ 8.62 (1H, d, J=2 Hz), 8.37 (1H, d, J=2 Hz), 7.33 (2H, m), 7.12 (2H, m), 4.05 (2H, s); ES+ MS: 313 (M+H+, 100), 311 (M+H+, 100).
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