214360-70-0

942070-22-6

General procedure for the synthesis of 2,5-dibromothiophene-3-boronic acid pinacol ester from thiophene-3-boronic acid pinacol ester: General method: to a solution of thiophene-3-boronic acid pinacol ester (50 mg, 0.21 mmol) in DMF (1 mL) was added N-bromosuccinimide (82 mg, 0.46 mmol). The reaction mixture was stirred at room temperature for 14 hours before the reaction was quenched with 10% Na2S2O3 aqueous solution (10 mL) and extracted with ether (10 mL x 3). The combined organic phases were washed sequentially with deionized water (10 mL x 2) and saturated saline (10 mL x 1) and dried over anhydrous magnesium sulfate. After the solvent was removed by concentration under reduced pressure, the residue was purified by silica gel column chromatography using hexane as eluent to afford 2,5-dibromothiophene-3-boronic acid pinacol ester (57.3 mg, 87% yield) as a colorless oil.