GENERAL METHOD: Under stirring conditions, 3-bromo-2-fluorobenzaldehyde (9.90 mmol) was dissolved in DMF (20 mL) and methyl mercaptoacetate (10.9 mmol) and potassium carbonate (39.6 mmol) were added sequentially. The reaction mixture was stirred continuously at 60 °C for 15 hours. After completion of the reaction, the DMF solvent was removed by distillation under reduced pressure. Water (50 mL) was added to the residue, which was subsequently extracted with ethyl acetate (2 x 40 mL). The organic phases were combined, dried with anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to remove the solvent to afford the target product, methyl 7-bromobenzo[b]thiophene-2-carboxylate.
