Hexafluoropropene reactions with nucleophiles

Reactions of perfluorinated alkenes, such as hexafluoropropene, with fluoride ion give perfluoroalkylcarbanions which can act as nucleophiles in S Ar reactions with perfluoroheteroaromatic systems (Fig. 8.13). These reactions are another example of mirror-image chemistry and reflect well-known Friedel-Crafts reactions of hydrocarbon systems that proceed by reaction of the corresponding electrophile and carbocationic intermediates. Poly substitution processes are possible and, indeed, all five fluorine atoms may be replaced upon reaction with an excess of tetrafluoroethylene and fluoride ion. ... 

Unsaturated fluorinated compounds are fundamentally different from those of hydrocarbon chemistry. Whereas conventional alkenes are electron rich at the double bond, fluoroal-kenes suffer from a deficiency of electrons due to the negative inductive effect. Therefore, fluoroalkenes react smoothly in a very typical way with oxygen, sulfur, nitrogen and carbon nucleophiles.31 Usually, the reaction path of the addition or addition-elimination reaction goes through an intermediate carbanion. The reaction conditions decide whether the product is saturated or unsaturated and if vinylic or allylic substitution is required. Highly branched fluoroalkenes, obtained from the fluoride-initiated ionic oligomerization of tetrafluoroethene or hexafluoropropene, are different and more complex in their reactions and reactivities. 

Similarly, dimethylphosphane reacts nucleophilically with hexafluoropropene to yield the trans-and m-substitution products in ratios which are dependent on the reaction conditions. Irradiation yields a 70 30 mixture of trans- and c/.v-dimethyl(pentafiuoroprop-l-enyl)phosphanes... 

Reactions of hexafluoropropene with N-oxides of various pyridine and quinoline derivatives120,121 provide an interesting process for introducing a polyfluoroalkyl group. The mechanism of the process has not been easy to formulate, but the most likely one now seems to be that shown in Scheme 12. The primary step in the addition of Af-oxides to unsaturated fluorocarbons could be formulated as either a nucleophilic attack or a concerted 1,3-dipolar... 

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