[F:1][C:2]1[CH:3]=[C:4]([C:9]2[C:13]([C:14](O)=[O:15])=[C:12](/[CH:17]=[CH:18]/[C:19]3[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=3)[O:11][N:10]=2)[CH:5]=[CH:6][C:7]=1[F:8].C(N(CC)CC)C.ClC(OCC)=O.[BH4-].[Na+].[OH-].[Na+]>C1COCC1.O>[F:1][C:2]1[CH:3]=[C:4]([C:9]2[C:13]([CH2:14][OH:15])=[C:12](/[CH:17]=[CH:18]/[C:19]3[CH:20]=[CH:21][CH:22]=[CH:23][CH:24]=3)[O:11][N:10]=2)[CH:5]=[CH:6][C:7]=1[F:8]To a solution of 3-(3,4-difluoro-phenyl)-5-([E]-styryl)-isoxazole-4-carboxylic acid (18 g, 55.0 mmol) and triethylamine (7.7 mL, 55.0 mmol) in THF (450 mL) was added at room temperature a solution of ethyl chloroformate (5.35 mL, 55.0 mmol) in THF (52 mL). After 1 h triethylamine hydrochloride salt was filtered off and washed with a small amount of THF. The solution was added to a solution of sodium borohydride (5.42 g, 138 mmol) in water (52 mL). The mixture was stirred overnight at room temperature. Sodium hydroxide solution (1 N, 180 mL) was added. Extraction with tert-butylmethylether and chromatography (silica, dichloromethane) afforded the title compound (12.6 g, 73%) as a light green solid. MS: m/e=314.2 [M+H]+.
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