Hydrochloric Acid → Methyl 5-hydroxybenzofuran-2-carboxylate

Participants

Reaction Steps

A solution of 5-dimethylcarbamoylsulfanyl-benzofuran-2-carboxylic acid methyl ester (0.5 g, 1.8 mmol) and potassium hydroxide (0.5 g, 12.5 mmol) in 25 ml 2:1 ethanol/water was heated at reflux for 18 hours. The reaction was then cooled, acidified with 2 M HCl, extracted 2×25 mL EtOAc, dried (Na2SO4) and the solvent removed in vacuo to give 350 mg of the crude product. The crude mixture was then refluxed overnight in 25 mL MeOH and catalytic H2SO4. The reaction was then cooled, concentrated in vacuo, taken up in EtOAc and washed with brine. The organic layer was then dried (Na2SO4) and concentrated in vacuo to give 330 mg (95%) of the title compound pure enough for subsequent use. 400 MHz 1H NMR (DMSO-d6) δ 7.66 (s, 1H), 7.62 (s, 1H), 7.57(d, 1H, J=9.0 Hz), 7.37 (d, 1H, J=9.0 Hz), 5.49 (s(br), 1H), 3.85 (s, 3H). Preparation of 5-[4-Methyl-2-(4-trifluoromethyl-phenyl)-thiazol-5-ylmethylsulfanyl]-benzofuran-2-carboxylic acid methyl ester (Compound 6E)

Provenance & Evidence