Skeletal transformations of pentafluorophenylation products of perfluorinated 1,2-dialkyl-1,2-dihydrocyclobutabenzenes in SbF5

Abstract

Perfluorinated 1-ethyl-2-methyl- and 1-isopropyl-2-methyl-1,2-dihydrocyclobutabenzenes reacted with pentafluorobenzene in SbF5 to generate perfluoro(1-ethyl-2-methyl-2-phenyl- and perfluoro(1-izopropyl-2-methyl-2-phenyl-1,2-dihydrocyclobutabenzen-1-yl) cations. These cations in SbF5 at 20°C underwent opening of the four-membered ring and its expansion to five-membered. After hydrolysis, perfluorinated 4-[1-(2-propylphenyl)ethylidene]- and 4-[1-(2-isobutylphenyl)ethylidene]-2,5-cyclohexadien-1-ones were obtained together with perfluoro(3-ethyl- and perfluoro(3-isopropyl-2-phenylinden-1-ones).