Cationoid rearrangements in reactions of perfluoro-1-arylbenzocyclobutenes with antimony pentafluoride

Skeletal transformations of perfluoro-1-ethyl-1-phenylbenzocyclobutene in the reaction with antimony pentafluoride

“…Perfluoro-1-(2-or 4-ethylphenyl)benzocyclobutenes when heated with SbF 5 give the products of alicyclic ring opening, which then convert to polyfluorinated fluorene or anthracene derivatives. In contrast to this, perfluoro-1-phenylbenzocyclobutene does not undergo skeletal transformations under the same conditions [13]. Perfluoro-1,2-diethyl-1-phenylbenzocyclobutene in mild conditions undergoes four-membered ring opening along with alicyclic and pentafluorobenzene rings expansion leading to polyfluorobenzoazulene derivatives [15].…”

“…There was reported in the literature the alicyclic ring contraction of 2-halopolyfluorotetralins in the reaction with SbF 5 [3] and the ring opening of perfluorocyclopropane derivatives under the action of antimony pentafluoride [4] or aluminium chlorofluoride [5]. Skeletal transformations of perfluorobenzocycloalkenes (benzocyclobutene, indan and tetralin) and their perfluoroalkyl and perfluoroaryl derivatives in the reactions with antimony pentafluoride have been investigated by us [6][7][8][9][10][11][12][13][14][15]. Thus, perfluoro-1-methyl-and 1-ethylbenzocyclobutenes undergo expansion of the four-membered ring to form polyfluoroindans [6].…”

The alicyclic ring contraction of perfluoro-1-phenyltetralin in reaction with antimony pentafluoride

“…Thus, the alicyclic ring contraction of 2-halopolyfluorotetralins in the reaction with SbF 5 [1] and the ring opening of perfluorocyclopropane derivatives under the action of antimony pentafluoride [2,3] or aluminium chlorofluoride [4] are both known. Skeletal transformations of the four-, five-and sixmembered alicyclic fragments of perfluorinated benzocyclobutene, indan, tetralin, and their perfluoroalkyl derivatives in an SbF 5 medium have been investigated, see for example [1][2][3][4][5][6][7] cited in our previous work [5].…”

“…When heated with antimony pentafluoride, perfluoro-1-(2-ethylphenyl)benzocyclobutene is converted to perfluoro-8,9-dimethyl-1,2,3,4-tetrahydrofluorene while perfluoro-1-(4-ethylphenyl)benzocyclobutene gives 2-ethyl-9,10-dihydroanthracene and perfluoro-6-ethyl-1,2,3,4-tetrahydroanthracene [6]. In contrast to this, perfluoro-1-phenylbenzocyclobutene does not undergo skeletal transformations under the same conditions [6].…”

Expansion of the pentafluorobenzene ring of perfluoro-1,2-diethyl-1-phenylbenzocyclobutene under the action of SbF5

“…In perfluoro-1-(2-or 4-ethylphenyl)benzocyclobutenes under the action of SbF 5 both alicyclic and aromatic fragments of the substrate are involved in the reaction to give polyfluorinated fluorene or anthracene derivatives. In contrast to this, perfluoro-1-phenylbenzocyclobutene does not undergo skeletal transformations under the same conditions [10].…”