Trifluoroacetic acid → ethyl 5-amino-3-methylthiophene-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

A mixture of ethyl 5-(tert-butoxycarbonylamino)-3-methylthiophene-2-carboxylate (25.00 g, 87.61 mmol) and trifluoroacetic acid (50 mL) in dichloromethane (100 mL) was stirred at 0° C. for 2 h, then concentrated in vacuo. The residue was partitioned between ethyl acetate (300 mL) and 1 N aqueous sodium hydroxide (300 mL). The aqueous layer was extracted with ethyl acetate (200 mL), and the combined organic layer was dried over sodium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography eluted with 40% ethyl acetate in hexanes to afford ethyl 5-amino-3-methylthiophene-2-carboxylate as a beige solid (14.44 g, 89%): 1H NMR (300 MHz, CDCl3) δ 5.95 (s, 1H), 4.25 (q, J=7.1 Hz, 2H), 2.41 (s, 3H), 1.32 (t, J=7.1 Hz, 3H); MS (ES+) m/z 186.2 (M+1).

Provenance & Evidence