Methyl 3-amino-2-thiophenecarboxylate → Methyl 3-(formylamino)-2-thiophenecarboxylate

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Reaction Steps

To a solution of 3-aminothiophene-2-carboxylic methyl ester (20 g, 127 mmol) in formic acid (100 mL) was added ammonium acetate (13 g, 169 mmol). The mixture was refluxed for 3 hours. After cooling to room temperature, the precipitate was filtered, washed with water and dried under vacuum to afford 3-formylaminothiophene-2-carboxylic acid methyl ester (20.5 g, 87%). 1H NMR (DMSO, 400 Hz) δ 10.38 (s, 1H), 8.42 (s, 1H), 8.00 (d, J=5.2 Hz, 1H), 7.90 (d, J=5.6 Hz, 1H), 3.84 (s, 3H). MS (ESI+) [M+H]+ 186.

Provenance & Evidence