Hydrochloric Acid → 4-Chlorothieno[2,3-B]pyridine-5-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of ethyl 4-chlorothieno[2,3-b]pyridine-5-carboxylate (800 mg, 3.31 mmol) [Khan, M. A.; Guarconi, A. E., J. Heterocyclic Chem., 14, 807 (1977)] in 15 mL of ethanol and 5 mL of 2.5 N sodium hydroxide is heated at reflux for 90 minutes. The mixture is cooled to 0° C. and the pH is adjusted to 4 by the addition of 2 N hydrochloric acid. The mixture is stirred at room temperature and the resulting precipitate is collected by filtration and washed with water to provide 250 mg of 4-chlorothieno[2,3-b]pyridine-5-carboxylic acid as a white solid, mp 172-174° C.; 1H NMR (DMSO-d6) δ 7.62 (d, J=6 Hz, 1H), 8.14 (d, J=6 Hz, 1H), 8.94 (s, 1H); MS 212.0 (M−H)−.

Provenance & Evidence