Sulfotrioxylation of internal fluoroolefins

The Chemistry of Highly Fluorinated Carbocations

“…210,214 According to one study, higher internal ∆ 2 perfluoroolefins do not interact with SO 3 in the presence of BF 3 , but a stronger Lewis acid, antimony pentafluoride, catalyzes the transformation of perfluoro-2alkenes into the corresponding allyl fluorosulfates 285-289. 215,216 In contrast to these results with higher internal fluoroolefins, boron catalysis does promote reaction of F-butene-2 with SO 3 at 100-150 °C, although reaction is slow and several days are required. 210 The reaction of equimolar amounts of F-butene-2 and SO 3 produces 1-fluoro F-2-butenesulfate (290) along with fluoro acylsulfate 291 and FSO 2 OSO 2 OSO 2 F (269b), all in low yield.…”

“…According to one study, higher internal Δ 2 perfluoroolefins do not interact with SO 3 in the presence of BF 3 , but a stronger Lewis acid, antimony pentafluoride, catalyzes the transformation of perfluoro-2-alkenes into the corresponding allyl fluorosulfates 285 − 289 . ,

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“…The structure of the catalyst complex formed by reaction of SbF 5 and SO 3 can probably be represented as Sb(OSO 2 F) n F 5 - n , The first or second mechanism could be realized depending on the structure of fluoroolefin and nature of Lewis acid.

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“…216 The replacement of activated fluorine atom in a substrate by the action of catalyst containing FSO 2 O-groups may proceed either as a reaction of virtually free carbocation 295 209,210 generated by abstraction of fluorine from olefin by the Lewis acid 5 or possibly as a concerted process involving a transitional complex such as 296 of the olefin with Lewis acid. 215,216 The first or second mechanism could be realized depending on the structure of fluoroolefin and nature of Lewis acid.…”