[CH3:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[CH:9]=[C:10]3[C:15](=[CH:16][CH:17]=2)[S:14][CH2:13][C:12]([C:18]([O:20]CC)=[O:19])=[CH:11]3)=[CH:4][CH:3]=1.[OH-].[Na+]>O1CCCC1.C(#N)C>[CH3:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[CH:9]=[C:10]3[C:15](=[CH:16][CH:17]=2)[S:14][CH2:13][C:12]([C:18]([OH:20])=[O:19])=[CH:11]3)=[CH:6][CH:7]=1To a solution of ethyl 6-(4-methylphenyl)-2H-thiochromene-3-carboxylate (2.12 g, 6.84 mmol) in tetrahydrofuran (20 ml) and acetonitrile (20 ml) was added dropwise 1N sodium hydroxide (7 ml), and the mixture was stirred at 60° C. for 2.5 hours. The solvent was evaporated, and the residue was dissolved in diethylether. The mixture was extracted with water. The organic layer was extracted with 0.5N sodium hydroxide, and both of the aqueous layers were made pH 3 with 6N hydrochloric acid. The mixture was extracted with ethyl acetate, and the organic layer was washed with saturated brine and dried with magnesium sulfate. The solvent was evaporated to give 6-(4-methyl-phenyl)-2H-thiochromene-3-carboxylic acid (1.83 g, 95%) as yellow powder.
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