Preparation of the E- and Z-heptafluorobutenyl-2-zinc reagent by zinc-induced dehalogenation/metallation of 2,2-dibromo-octafluorobutane

Article abstract of DOI:10.1016/0022-1139(93)02905-T

The AlCl3-catalyzed isomerization of CF3CFBrCFBrCF3 afforded CF3CF2CBr2CF3, which upon treatment with 2 equiv. zinc in DMF underwent dehalogenation/metallation to afford a 1:1 mixture of E- and Z-CF3CF=C(ZnX)CF3 in 96percent 19F NMR yield.The zinc reagent exhibited poor thermal stability in DMF and completely decomposed by a β-elimination route in 24 h at 60 deg C.However, the zinc reagent prepared from E- and Z-CF3CF=CICF3 in triglyme showed enhanced thermal stability and gave E- and Z-p-NO2C6H4C(CF3)=CFCF3 in a palladium-catalyzed coupling reaction with p-NO2C6H4I.