C(O)CO.[S:5]1[C:9]2[CH:10]=[CH:11][C:12]([CH:14](C(OCC)=O)[C:15]([O:17]CC)=[O:16])=[CH:13][C:8]=2[CH:7]=[CH:6]1.[OH-].[K+].O>C1(C)C=CC=CC=1>[S:5]1[C:9]2[CH:10]=[CH:11][C:12]([CH2:14][C:15]([OH:17])=[O:16])=[CH:13][C:8]=2[CH:7]=[CH:6]1To ethylene glycol (1.0 mL) suspension of 0.25 g of diethyl 2-(1-benzothiophen-5-yl)malonate were added 1.0 mL of 40% (w/w) potassium hydroxide aqueous solution and 0.3 mL of water, which was then refluxed for 2 hours. To the reaction mixture were added water and toluene, and the aqueous layer was separated. The pH was adjusted to 2 with 6 mol/L hydrochloric acid, and thereto was added ethyl acetate. The organic layer was separated, and dried over anhydrous magnesium sulfate, followed by distilling off the solvent under reduced pressure. The resultant residue was suspended to 5 mL of xylene, and thereto was added 0.01 g of p-toluenesulfonic acid monohydrate, which was then refluxed for 30 minutes. The solvent was distilled off under reduced pressure, and to the resultant residue were added toluene and cyclohexane. The precipitate was collected by filtration to provide 0.02 g of 2-(1-benzothiophen-5-yl)acetic acid as pale yellow solid form.
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