Pyrolysis reactions of 4-nonafluorobiphenyl prop-2-enyl ether: a remarkable rearrangement reaction

The formation of the unexpected bicyclic compound 16 via the pyrolytic isomerisation of 4-nonafluorobiphenyl prop-2-enyl ether 8 can be rationalised by invoking the intermediacy of a rare retro-cyclisation reaction of the internal Diels-Alder adduct 12 (from the Claisen intermediate 9) to a tethered ketene 18, recyclisation via the alternative mode to 17 and its subsequent transformation.