1047630-72-7

35475-03-7

1047630-72-7

General procedure for the synthesis of methyl 5-chloro-4-bromothiophene-2-carboxylate from methyl 5-chlorothiophene-2-carboxylate: To a 1 L round bottom flask was added aluminum chloride (11.32 g, 85 mmol) and methyl 5-chlorothiophene-2-carboxylate (10 g, 56.6 mmol) dissolved in chloroform (250 mL). Bromine (4.08 mL, 79 mmol) was added slowly and dropwise over 10 min. The reaction mixture was stirred at 25 °C for 6 h. The light orange reaction solution was washed with saturated sodium bicarbonate solution. The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated. The residue was purified by silica gel column chromatography [n-hexane/ethyl acetate, 9:1] to give the target product (12 g, 80% yield) as a white solid.LC-MS (ESI) m/z 256 ([M+H]+).