Carbonylation of Polyfluorobenzocyclobutenones in a SbF₅ Medium

The carbonylation of perfluoro-2-R-benzocyclobutenones (R = F, CF₃, C₂F₅, C₆F₅) in a CO-SbF₅ system is accompanied by transformations of the four-membered cycle in the substrate to form polyfluorinated 1H-isochromene derivatives. The reaction of perfluoro-2-R-benzocyclobutenes (R = F, CF₃, C₂F₅) with (CF₃CO)₂O or CF₃COOH in a SbF₅ medium in a sealed ampule involves formation of polyfluorobenzocyclobutenones and their carbonylation under the reaction conditions.