Hydrogen Bromide → Methyl 3-bromothiophene-2-carboxylate

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Reaction Steps

3-Amino-2-thiophenecarboxylic acid methyl ester (9.4 g) was suspended in hydrobromic acid (20 ml), and the mixture was stirred at room temperature for 30 minutes. The mixture was cooled to 0° C., and sodium nitrite (4.2 g) in water (10 ml) was added dropwise below 10° C. The mixture was stirred for 1 hour, and then poured into copper (I) bromide (9.06 g) in hydrobromic acid (25 ml). The resulting mixture was stirred at 60° C. for 1 hour and extracted with diethyl ether. The extract was dried over anhydrous magnesium sulfate and concentrated under reduced pressure and distilled under reduced pressure to give 3-bromo-2-thiophenecarboxylic acid methyl ester (7.99 g) as crystals.

Provenance & Evidence