[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]([CH2:15][CH3:16])=[CH:9][C:10]([O:12][CH2:13][CH3:14])=[O:11])=[CH:4][CH:3]=1.[H][H]>[Pd].C(O)C>[F:1][C:2]1[CH:3]=[CH:4][C:5]([CH:8]([CH2:15][CH3:16])[CH2:9][C:10]([O:12][CH2:13][CH3:14])=[O:11])=[CH:6][CH:7]=1A mixture of ethyl 3-(4-fluorophenyl)pentenoate (45.65 g, 0.137 mol) and 10% palladium on carbon (0.86 g, Aldrich) in 95% ethanol was shaken under 4 atm hydrogen pressure in a Parr hydrogenator for 1.5 hr. The mixture was filtered and concentrated by spin evaporation in vacuo. Fractional distillation gave 38.95 g (63%) of ethyl 3-(4-fluorophenyl)valerate as a clear oil contaminated with 29% triethyl phosphonoacetate, b.p., 133-142° C. at 17 mm Hg:
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