General procedure for the synthesis of 3-fluoro-5-bromobenzyl bromide from (3-bromo-5-fluorophenyl)methanol: 3-bromo-5-fluorobenzyl alcohol (1.79 g, 8.39 mmol) and triphenylphosphine (3.65 g, 10.10 mmol) were dissolved in dichloromethane (45 mL), followed by addition of carbon tetrabromide (3.34 g, 10.10 mmol). The reaction mixture was stirred at room temperature overnight. After completion of the reaction, the solvent was removed by vacuum evaporation. The residue was treated with diethyl ether (50 mL) and stirred at room temperature to form a white slurry. The slurry was filtered through CeliteTM and the residue was washed with diethyl ether (2 x 50 mL). The filtrate and washings were combined and the crude product was obtained by vacuum evaporation. The crude product was purified by silica gel column chromatography using 2% ethyl acetate/hexane as eluent to afford 3-bromo-5-fluorobenzyl bromide (2.21 g, 98%). The structure of the product was confirmed by 1H NMR, 19F NMR and 13C NMR.1H NMR (400 MHz, CDCl3): δ 7.33 (s, 1H), 7.18 (ddd, JHF 8.2 Hz, JHH = 2.0,2.0 Hz, 1H), 7.05 (ddd, JHF = 9.0 Hz, JHH = 1.8,1.6 Hz. 1H), 4.38 (s, 2H); 19F NMR (377 MHz, CDCl3): δ -110.19 to -110.14 (m, 1F); 13C NMR (101 MHz, CDCl3): δ 162.67 (d, JCF = 252.1 Hz), 141.61 (d, JCF = 8.5 Hz), 128.17 ( d, JCF = 3.1 Hz), 122.94 (d, JCF = 10.0 Hz), 119.39 (d, JCF = 24.6 Hz), 115.34 (d, JCF = 22.3 Hz), 31.31 (d, JCF = 2.3 Hz).
