O=[CH:2][CH2:3][CH2:4][CH2:5][CH2:6][CH2:7][CH2:8][CH2:9][CH2:10][CH2:11][C:12]([O:14][CH3:15])=[O:13].Br[C:17](Br)([F:19])[F:18].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>CC(N(C)C)=O.O.[Zn]>[F:18][C:17]([F:19])=[CH:2][CH2:3][CH2:4][CH2:5][CH2:6][CH2:7][CH2:8][CH2:9][CH2:10][CH2:11][C:12]([O:14][CH3:15])=[O:13]
A stirred mixture of 7.5 grams (0.035 mole) of methyl 11-oxoundecanoate and 14.7 grams (0.07 mole) of dibromodifluoromethane was cooled to 0°-10° C., and a solution of 18.4 grams (0.07 mole) of triphenylphosphine in 50 ml of dimethylacetamide was added dropwise. During the addition the temperature of the reaction mixture was maintained at 0°-10° C. Upon completion of addition the reaction mixture was allowed to warm to ambient temperature, and 4.6 grams (0.07 mole) of zinc dust was added in two portions. The addition caused an exothermic reaction which raised the temperature of the reaction mixture to 90° C. The reaction mixture was allowed to cool to ambient temperature where it stood without stirring for 60 hours. The reaction mixture was diluted with water and was subjected to a steam distillation with pentane. The appropriate fractions were combined and concentrated under reduced pressure yielding 4.3 grams of methyl 12,12-difluoro-11-dodecenoate. The nmr spectrum was consistent with the proposed structure.
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