[F:1][C:2]1([F:19])[CH2:7][CH2:6][C:5](O)([C:8]([O:10][CH2:11][C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[O:9])[CH2:4][CH2:3]1.P(Cl)(Cl)(Cl)=O.[Cl-].[NH4+]>N1C=CC=CC=1>[F:1][C:2]1([F:19])[CH2:7][CH2:6][C:5]([C:8]([O:10][CH2:11][C:12]2[CH:13]=[CH:14][CH:15]=[CH:16][CH:17]=2)=[O:9])=[CH:4][CH2:3]1To a solution of benzyl 4,4-difluoro-1-hydroxycyclohexanecarboxylate (1.8 g, 6.66 mmol) in 13 ml of pyridine was added phosphorous oxychloride (1.12 g, 7.33 mmol). The resulting solution was stirred under nitrogen at room temperature for 18 hours, and then poured into 70 mL of saturated ammonium chloride solution and extracted with ethyl acetate. The combined ethyl acetate extracts were washed with 2 molar hydrochloric acid solution and brine and then dried over sodium sulfate. Filtration and concentration under vacuum afforded the crude product which was purified by chromatography on silica gel eluting 2% ethyl acetate in hexanes to give benzyl 4,4-difluorocyclohex-1-ene-1-carboxylate as an oil.
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