Methanol → Methyl 5-bromothiophene-2-carboxylate

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Reaction Steps

To a solution of 5-bromo-thiophene-2-carboxylic acid (1.04 g, 5.0 mmol) in 15 mL of methanol, add concentrated sulfuric acid (0.5 ml, 10 mmol). After heating to reflux for an hour, cool the reaction to room temp, and dilute with EtOAc/H2O=50/50. Then, neutralize with 1.0 N NaOH to pH=7, extract the aqueous solution with ethyl acetate (30 ml×3), and dry the combined organic layers over sodium sulfate. Purify the crude material via flash chromatograpgy on sila gel to give the title compound 0.62 g. GC/MS (m/z) 222 (M+1), 191 (M—OMe+1).

Provenance & Evidence