Cl[CH2:2][C:3]([C:13]1[CH:18]=[CH:17][C:16]([F:19])=[CH:15][C:14]=1[F:20])([OH:12])[C:4]([F:11])([F:10])[C:5]([O:7][CH2:8][CH3:9])=[O:6].N12CCCN=C1CCCCC2.O.Cl>C(Cl)Cl>[F:20][C:14]1[CH:15]=[C:16]([F:19])[CH:17]=[CH:18][C:13]=1[C:3]1([O:12][CH2:2]1)[C:4]([F:11])([F:10])[C:5]([O:7][CH2:8][CH3:9])=[O:6]In 150 ml of methylene chloride was dissolved 15.7 g of ethyl 4-chloro-3-(2,4-difluorophenyl)-2,2-difluoro-3-hydroxybutyrate. To the solution was dropwise added 8.4 g of 1,8-diazabicyclo[5.4.0]undec-7-ene at 5°-10° C. The mixture was subjected to reaction at the same temperature for 2 hours. The resulting reaction mixture was introduced into 150 ml of water and adjusted to p 1.0 with 6N hydrochloric acid. The organic layer was separated, washed with a saturated aqueous sodium chloride solution, and then dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure. The residue thus obtained was purified by a column chromatography (eluant: n-hexane/toluene=2/1) to obtain 11.1 g of oily ethyl 3-(2,4-difluorophenyl)-3,4-epoxy-2,2-difluorobutyrate.
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