[Cl:1][C:2]1[CH:3]=[C:4]([CH:9]=[CH:10][C:11]([CH3:18])=[CH:12][C:13]([O:15]CC)=[O:14])[CH:5]=[CH:6][C:7]=1[Cl:8].[OH-].[Li+].O1CCOCC1>O1CCCC1>[Cl:1][C:2]1[CH:3]=[C:4]([CH:9]=[CH:10][C:11]([CH3:18])=[CH:12][C:13]([OH:15])=[O:14])[CH:5]=[CH:6][C:7]=1[Cl:8]A solution of ehtyl 5-(3,4-dichlorophenyl)-3-methyl-pentadienoate (0.120 g, 0.418 mmol) in tetrahydrofuran (0.5 mL) is treated with aqueous 1 M lithium hydroxide (0.5 mL, 0.5 mmol). The cloudy reaction mixture is treated with dioxane (1 mL). After stirring at room temperature for two days, the mixture is concentrated in vacuo. The residue is diluted with 1 M aqueous HCl and extracted several times with chloroform. The organic layers are combined, dried (sodium sulfate), and concentrated in vacuo to yield 0.110 g of a white solid, mp, 212-214° C.
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