Alkenes perhalogenated fluoride

With very electrophilic olefins, an alternative hydrogen fluoride addition process is often preferred This process, involving reaction of the olefin with fluoride ion in the presence of a proton donor, is applicable to certain perhalogen ated alkenes [/] and substrates with other electron attracting groups attached to the double bond [i5, 36] (equations 4 and 5)... 

Treatment of perhalogenated and highly halogenated alkenes with sulfur tetrafluoride in the presence of lead(IV) oxide, which is most likely converted in situ into lead(IV) fluoride, results in addition of fluorine to the C = C bond of the alkenes. The addition proceeds at 100 C to afford per- and polyhalogenated alkanes 5 in yields ranging from a few percent to almost quantitative.190 Representative examples are given. 

When trialkylphosphites are treated with fluoroalkanoyl chlorides, perhalogenated fluoro-alkenes, perfluorinated aromatics, and other fluorinated alkylating substrates, an Arbuzov reaction takes place and alkyl fluorides are formed as byproducts. The method has been used to prepare 6-fluoro-6-deoxy-l,2 3,4-di-f7-isopropylidenegalactose (1). ... 

Table 8 summarizes further examples of the nucleophilic addition of hydrogen fluoride to perhalogenated alkenes with potassium fluoride in formamide. 

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