Preparation of [5,6]- and [6,6]-oxahomofullerene derivatives and their interconversion by lewis acid assisted reactions of fullerene mixed peroxides

[60]Fullerene mixed peroxides C-60(O)(OOtBu)(4) exhibit chemoand regioselective reactions under mild conditions. The epoxy moiety is opened by ferric chloride to form vicinal hydroxy chloride C60Cl(OH)(OOtBu)-BF3 is also effective in opening the epoxy moiety. The O-O bond of the fullerene mixed peroxide is cleaved by both [5,6]- and type aluminum chloride to form and [6,6]-fullerene hemiketals (oxohomo[60]fullerenes). A Hocktype rearrangement is proposed for the formation of the hemiketals, in which a fullerene C-C bond is cleaved. Lewis acids and/or visible light can initiate isomerization of the hemiketal isomers. Single-crystal X-ray analysis and theoretical calculations confirmed the results.