The first carbonylation of perfluoroorganic compounds: The reactions of perfluorobenzocyclobutene and its perfluoroalkyl and pentafluorophenyl derivatives with CO in SbF5 medium

Carbonylation of polyfluorinated benzocyclobutenes with CO in an SbF5 medium readily proceeds at room temperature and atmospheric pressure and it is followed by four-membered ring transformations. Perfluorinated benzocyclobutene, 3- and 4-methyl-benzocyclobutenes add two CO molecules to form, after ring opening and following heterocyclization, isochromene derivatives. Hydrolysis of the reaction mixtures gives corresponding 4-carboxy-1H-isochromenes and 2-(carboxymethyl)benzoic acids. The carbonylation of perfluorinated 1-methyl-, 1-ethyl- and 1-isopropyl-benzocyclobutene gives salts of 2-(2-methylphenyl)alk-2-enoyl cations and the corresponding acids after hydrolysis of the latters. Perfluoro-1-phenylbenzocyclobutene in the reaction with CO–SbF5 transforms into a salt of perfluro-4-phenylisochromenyl cation, its hydrolysis gives perfluro-4-phenylisochromen-1-one.