[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[O:12][N:11]=[C:10]([C:13]3[CH:22]=[CH:21][C:16]([C:17]([O:19]C)=[O:18])=[CH:15][CH:14]=3)[CH:9]=2)=[CH:4][CH:3]=1.[OH-].[Na+].O1CCCC1.Cl>O.CO>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[O:12][N:11]=[C:10]([C:13]3[CH:22]=[CH:21][C:16]([C:17]([OH:19])=[O:18])=[CH:15][CH:14]=3)[CH:9]=2)=[CH:6][CH:7]=1A mixture of methyl 4-[5-(4-chlorophenyl)-3-isoxazolyl]benzoate (1.35 g), 1 M aqueous sodium hydroxide solution (10 ml), tetrahydrofuran (20 ml) and methanol (10 ml) was stirred at 60° C. for 1 hr. After cooling, the reaction mixture was poured into water, and 1 M hydrochloric acid (10 ml) was added. The crystals were collected by filtration, and recrystallized from tetrahydrofuran-hexane to give 4-[5-(4-chlorophenyl)-3-isoxazolyl]benzoic acid (1.19 g, yield 92%) as colorless crystals. melting point: >300° C.
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