[F:1][C:2]1[CH:7]=[CH:6][C:5]([CH3:8])=[CH:4][C:3]=1[O:9][C:10](=[O:17])[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1.[Br:18]N1C(=O)CCC1=O.C(OOC(=O)C1C=CC=CC=1)(=O)C1C=CC=CC=1.O>C(Cl)(Cl)(Cl)Cl.C(OCC)C>[Br:18][CH2:8][C:5]1[CH:6]=[CH:7][C:2]([F:1])=[C:3]([O:9][C:10](=[O:17])[C:11]2[CH:12]=[CH:13][CH:14]=[CH:15][CH:16]=2)[CH:4]=1A mixture of benzoic acid 2-fluoro-5-methyl-phenyl ester (CAB02145, 2.47 g, 10.0 mmol), N-bromo-succinimide (1.96 g, 11.0 mmol) and dibenzoylperoxide (10 mg) in carbon tetrachloride (25 mL) was heated to reflux for 2 h (TLC monitored). After cooling to room temperature, water (50 mL) and diethyl ether (100 mL) were added. The organic layer was separated, washed with brine (20 mL), dried over sodium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography (EtOAc:hexane, 1:25, Rf: 0.28). Yield: 1.80 g (58%), white solid. 1H-NMR (400 MHz, CDCl3) δ=4.48 (s, 2H, —CH2Br), 7.18 (dd, J=9.8, 8.6 Hz, 1H), 7.28 (ddd, J=8.6, 4.3, 2.3 Hz, 1H), 7.34 (dd, J=7.0, 2.3 Hz, 1H), 7.50-7.55 (m, 2H), 7.64-7.69 (m, 1H), 8.18-8.23 (m, 2H). LRMS (FAB+): 229.1 (95), 309.0 (100, [M+]+). Found: C, 54.1, H, 3.22%; C14H10BrFO2 (309.13) requires C, 54.39, H, 3.26%.
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