Hydrochloric Acid → Methyl 4-aminothiophene-3-carboxylate

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Reaktionsschritte

HCl (1M solution in ether, 125 mL) was added slowly to a solution of 4-hydroxyimino-tetrahydro-thiophene-3-carboxylic acid methyl ester (34) (18.30 g, 104 mmol) in dry ether (200 mL) and dry methanol (50 mL) stirred at room temperature. The solution was further stirred at room temperature under argon for 24 h. The solids formed were filtered, washed by cold ether, and dried to yield 18.20 g (91%) of 4-amino-thiophene-3-carboxylic acid methyl ester as the hydrochloride salt. MP 198° C.; 1H NMR (400 MHz, DMSO-d6) δ 3.86 (s, 3H), 7.22 (d, J=2.4 Hz, 1H), 8.37 (d, J=3.2 Hz, 1H) ppm; MS m/z=158 amu (M++1).

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