Valence-bond isomer chemistry. Part 11 [1]. Thermal rearrangement of the Diels-Alder adduct of hexafluorobicyclo-[2.2.0]hexa-2,5-diene and 2,3-Dimethylbuta-1,3-diene: a [1,3] sigmatropic shift of fluorine

Flow pyrolysis of the Diels-Alder adduct of hexafluorobicyclo2.2.0]hexa-2,5-diene and 2,3-dimethylbutadiene gives an unusual product, the Diels-Alder adduct of hexafluorobenzene and 2,3-dimethylbuta-1,3-diene, and thence via an exclusive 1,3] sigmatropic fluorine shift, its isomeric triene. Loss of hydrogen fluoride from the unusual Diels-Alder adduct readily affords 1,2,3,4-tetrafluoro-6,7-dimethylnaphthalene.