Transformations of perfluorinated 1-alkyl-, 1-phenyl- and 1,2-dialkylbenzocyclobutenes under the action of SiO2/SbF5

Heating of perfluorinated 1-methyl-, 1-ethyl- and 1-isopropylbenzocyclobutenes with SiO2 in an SbF5 medium at 75 °C results in perfluoro-2-alkylbenzocyclobutenones or perfluoro-3-alkylphthalides formation. Perfluorinated 1,2-diethyl- and 1-ethyl-2-methylbenzocyclobutenes react with SiO2/SbF5 at 75 °C to form, after treatment of the reaction mixture with water, perfluorinated 1,3-diethyl- and 1-ethyl-3-methylphthalan-1,3-diol, respectively. Perfluoro-1,2-diisopropylbenzocyclobutene under the action of SiO2/SbF5 at 95 °C is converted to perfluoro-7,8-diisopropylbicyclo[4.2.0]octa-1,5,7-triene-3,4-dione and perfluoro-1,2-diisobutyrylbenzene. Perfluoro-1-methyl-2-phenylbenzocyclobutene does not react with SiO2 in an SbF5 medium at 75 °C, perfluoro-1-phenylbenzocyclobutene in analogous conditions gives a mixture of perfluorinated 2-hydroxy-2-phenylbenzocyclobutenone and 2-benzoylbenzoic acid.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Rearrangements of perfluoroalkylbenzocyclobutenes in the reaction with SiO2/SbF5. ► Involvement of SiO2 in the four-membered ring cleavage. ► The influence of the substituent group on the reaction route.