SKELETAL REACTIONS OF PERFLUOROMETHYLETHYL- AND PERFLUORODIETHYLBENZOCYCLOBUTENES WITH 1,1- AND 1,2-ALKYL GROUPS IN SbF5

Article abstract of DOI:10.1007/BF00961700

Taking perfluoro-1,1-dialkylbenzocyclobutenes as examples, it has been shown to be possible to enlarge the four-membered ring in polyfluorobenzocyclobutenes to five-membered in the presence of SbF5 by cleavage of the four-membered ring followed by cyclization of the resulting polyfluorostyrene to the polyfluoroindane, which then undergoes further reactions.Perfluoro-1-methyl-1-ethylbenzocyclobutene isomerizes at 50 deg C in the presence of SbF5 to perfluoro-α,β-o-trimethylstyrene, which is reversibly converted at 130 deg C into perfluoro-1,2-dimethylindane.Perfluoro-1,1-diethylbenzocyclobutene isomerizes at 130 deg C in the presence of SbF5 to give perfluoro-α-ethyl-β,o-dimethylstyrene, which at 170 deg C gives perfluoro-2-methyl-3-ethylindene- and perfluoro-2-methyl-3-ethyl-4,5,6,7-tetrahydroindene.The last two compounds, together with perfluoro-o-dipropylbenzene, are obtained from perfluoro-1,2-diethylbenzocyclobutene with SbF5 at 170 deg C.From perfluoro-1-methyl-2-ethyl-benzocyclobutene with SbF5 at 95 deg C there is obtained perfluoro-1-ethylindane, while at 130 deg C, in addition to the latter compound, there are obtained perfluorinated 1,1-dimethylindane, 1,2-dimethylindane, α,β,o-trimethylstyrene, 2,3-dimethylindene, and 2,3-dimethyl-4,5,6,7-tetrahydroindene.