To a round bottom flask, an unseparated mixture of 7-fluoro-6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene and 5,7-difluoro-6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene (380 mg, 1.318 mmol) was dissolved in THF (10 mL) and the solution was cooled to 0° C. To the solution was added NBS (237 mg, 1.331 mmol). The reaction mixture was stirred at 0° C. for 1 h then warmed to room temperature and stirred for an additional 2 h. The reaction mixture was concentrated to afford the crude product. The crude product was diluted with DCM and sat. Na2S2O3 (sodium thiosulfate). The organic layer was collected (phase separator) and concentrated. The reaction mixture was diluted with water and DCM. The organic phase was collected (phase separator) and concentrated to afford the crude product. The crude material was purified by column chromatography (SiO2, 0-5% Heptanes/EtOAc) to afford 3-bromo-7-fluoro-6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene (211 mg, 0.575 mmol, 43.6% yield) and 3-bromo-5,7-difluoro-6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene (125 mg, 0.324 mmol, 24.62% yield). 3-bromo-7-fluoro-6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene: 1H NMR (400 MHz, CDCl3) δ ppm=7.56-7.66 (m, 2H), 7.46 (dd, J=1.01, 8.59 Hz, 1H), 7.11 (dd, J=7.58, 8.59 Hz, 1H), 6.90-6.97 (m, 2H), 3.92 (s, 3H), 3.79 (s, 3H). 3-bromo-5,7-difluoro-6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene: 1H NMR (400 MHz, CDCl3) δ ppm=7.53-7.68 (m, 2H), 7.48 (d, J=8.59 Hz, 1H), 7.15-7.27 (m, 1H), 7.07 (dt, J=2.53, 8.59 Hz, 1H), 3.98 (s, 3H), 4.02 (s, 3H).
