Benzo[b]thiophene, 2-[(5-broMo-2-fluorophenyl)Methyl]-

1034305-11-7

1034305-17-3

General procedure for the synthesis of 2-(5-bromo-2-fluorobenzyl)benzo[b]thiophene from benzo[b]thiophen-2-yl(5-bromo-2-fluorophenyl)methanol: 35.4 g (105 mmol) of benzo[b]thiophene-2-yl(5-bromo-2-fluorophenyl)methanol, a compound of Formula 3, was dissolved in 800 mL of dichloromethane, and the solution was cooled to -20 °C. To this solution, 36.5 mL (230 mmol) of triethylsilane and 15.2 mL (120 mmol) of boron trifluoride ethyl ether compound were slowly added under stirring. The reaction mixture was kept stirred at -20°C for 30 minutes. Upon completion of the reaction, saturated aqueous sodium bicarbonate solution was added to the mixture to neutralize the reaction. The organic phase was separated, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to remove the solvent. The resulting crude product was purified by column chromatography (eluent: ethyl acetate/hexane mixed solvent) to afford the target product 2-(5-bromo-2-fluorobenzyl)benzo[b]thiophene (Compound 4) 30.4 g, with 99.5% purity and 90.1% yield.