Alkenes perhalogenated

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. 

Finally perfluorinated alkenes, prepared according to various routes (decarboxylation of perfluorinated acids or anhydrides, action of organolithium, magnesium reagents or metallic zinc-copper couple to perfluoroalkyl iodides, oligomerisation of TFE and of HFP, addition of perfluoroalkyl iodides to per-fluoroallyl chloride [304], addition of KF to perhalogenated esters or alkanes... 

With a combination of organic halide, alkene or alkyne, and palladium catalyst, the reaction may take a superficially similar, but different pathway other than a Heck-type reaction. In these, the halogen is retained in the products, as an alkyl or vinyl halide. These results occur when the starting organic halide is allyl, a- to a carbonyl or similar group, or attached to a perhalogenated carbon atom. In much of the early work, mixtures with Hecklike elimination products were obtained, due to elimination caused by the presence of amine bases in the reaction mixture (equation 165)323. 

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). ... 

Addition of dialkyl or cyclic ethers to perhalogenated alkenes occurs readily under y-ray irradiation. For example, addition of hexafluoropropene to tetrahydrofuran. ... 

Vinylic halogen atoms in perhalogenated alkenes are easily substituted by an addition-elimination mechanism with secondary phosphanes. 

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

Vinylic Halogen Atoms in Perhalogenated Alkenes and Phosphanes... 

Perfluoroalkenes and perfluorinated chloroalkenes add secondary amines to give a,a-difluo-roamines (47 equation 28). The A -halogenated amine (48) reacts with perhalogenated alkenes in a similar fashion, (equation 29). ... 

Perhalogenated cyclopropenes, such as 1,2,3,3-tetrachlorocyclopropene, are similarly converted into a copper carbenoid species with copper(I) chloride at 110-130°C. The intermediate can then be trapped with various alkenes to yield l-chloro-l-(trichloroethenyl)cyclopropanes in moderate to good yields.Yields and product distributions are often comparable to those obtained in thermal reactions. 

Die Addition von Alkoholen bzw. Phenolen an Perhalogen-1-alkene (Ausfiihrung, Unifang, Bedeutung und Grenzen der Synthese) wurde bereits ausfiihrlich in ds. Handb. be-... 

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