Potassium Hydroxide → HCID 19100820, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred mixture of ethyl 2-t-butoxycarbonylamino-4-cyclopropylthiophene-3-carboxylate (2.7 g, 8.7 mmol) and ethyl 2-bis(t-butoxycarbonyl)amino-4-cyclopropylthiophene-3-carboxylate (4.5 g, 10.9 mmol) in methanol (150 ml), a solution of potassium hydroxide (5.3 g, 95 mmol) in water (55 ml) was added. After heating at 60° C. for 6 h, the mixture was concentrated in vacuo and the residue taken up in water (50 ml) followed by acidification (pH=5) with acetic acid under cooling on ice. The precipitate was filtered off and recrystallized from ethyl acetate/ petroleum ether to afford (4.2 g, 70%) of 2-t-butoxycarbonylamino-4-cyclopropylthiophene-3-carboxylic acid. M.p. 175°-176° C. 1H-NMR (CDCl3, δ): 0.6 (m, 2H), 0.9 (m, 2H), 1.55 (s, 9H), 2.35 (m, 1H), 6.2 (s, 1H), 10.15 (s, 1H).

Provenance & Evidence