New Routes to Hexafluorocyclopentadiene and Related Compounds

Article abstract of DOI:10.1021/jo00350a079

Hexafluorocyclopentadiene (1) has been synthesized in two steps from pentafluorophenol (2) by fluorination followed by flash vacuum pyrolysis of the resulting hexafluorocyclohexadienones 3 and 4.Similar pyrolysis of 6-chloropentafluorocyclohexadienone (13) gave an equilibrium mixture of 1- and 2-chloropentafluorocyclopentadiene (15 and 16), presumably via the 5-chloro isomer.Flash vacuum pyrolysis of tetrafluoro-o-benzoquinone 17 yielded tetrafluorocyclopentadienone (20).Hexafluorocyclopentadiene was also prepared via a ring-expansion route which entailed cycloaddition (accompanied by rearrangement) of bromotrifluoroethylene to tetrafluorocyclopropene followed by reductive debromofluorination.