4,5,6,7-Tetrahydro-benzo[b]thiophene-3-carboxylic acid

Synthesis

The general procedure for the synthesis of 4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylic acid from ethyl 4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate was as follows: general method: potassium hydroxide (KOH, 1.7 g, 30 mmol) was added to ethyl 4,5,6,7-tetrahydrobenzo[B]thiophene-3-carboxylate (30 mmol) in aqueous (H2O. 20 mL) emulsion. The mixture was heated under vigorous stirring until a clarified solution was obtained (about 1 h), then stirring was continued for 30 min. The reaction solution was cooled to room temperature and washed with toluene (PhMe); the aqueous layer was separated and acidified with hydrochloric acid (HCl) to pH 4. The precipitate was collected by filtration and recrystallized with a solvent mixture of ethanol (EtOH)-N,N-dimethylformamide (DMF).

References

[1] Journal of Medicinal Chemistry, 2003, vol. 46, # 12, p. 2446 - 2455
[2] Chemistry of Heterocyclic Compounds, 2015, vol. 50, # 12, p. 1748 - 1755
[3] Khim. Geterotsikl. Soedin., 2014, vol. 50, # 12, p. 1900 - 1907,8