Perfluoroalkylcopper

Table 6, Perfluoroalkyl Aromatic Compounds Prepared via the Reaction of Perfluoroalkylcopper Reagents with lodo-or Bromoaromatic Compounds...

At higher temperatures, an oligomeric mixture of perfluoroalkylcopper reagents IS obtained [272] (equation 142). 

Perfluorovinyl iodides readily undergo stereospecific coupling with the tn-fluoroinethylcopper solution [224] (equation 151) prepared from dibromodifluo-romethane [210] With longer-chain perfluoroalkylcopper reagents, the coupling reaction is accompanied by some exchange processes [225] (equation 152)... 

Perfluoroalkylcopper reagents couple with I-iodnacetylenic derivatives to... 

Perfluoroalkylcopper reagents react with thiocyanates to give perfluoro-alkyl-substituted sulfides in low yields [230] and with benzoylformyl chloride to give the oi-diketone in 49% yield [231] However, other a-ketoacyl halides were prepared in less than 5% yield [231]... 

Perfluoroalkylation of olefins and acetylenes occurs in low yields when perfluoroalkylcopper reagents are heated with alkenes or acetylenes in DMSO [226, 237, 238, 239]. Undine derivatives react similarly [240]... 

The DMF solution of CF3Cu slowly decomposes at room temperature to form pentafluoroethylcopper [92] and at higher temperature to form an oligomeric mixture of perfluoroalkylcopper reagents [93] (Scheme 31). 

Perfluoroalkylcopper reagents couple with 1-iadoacetylenic derivatives to give the expected perfluoroalky(-substituted acetylenes [226] (equation 153) The coupling reaction is complicated by formation of the diyne from competitive exchange processes... 

Allylation is a facile process and will occur with any perfluoroalkylcopper reagents [207, 224] Typical examples are shown below in equations 154 and 155... 

Burton has investigated the alkylation of allyl halides with perfluoroorganocoppers. Both perfluoroalkylcoppers and perfluoroalkenylcoppers couple with allyl bromide in high yield the former also couples effectively with allyl chloride (equation 38)51 13. Doublebond stereochemistry is preserved with alkenylcopper reagents, while issues of a-/y-regio-selectivity of attack on the allyl unit have yet to be addressed. 

Coupling of aryl iodides has also been effected with perfluoroalkylcoppers and perfluo-rovinylcopper reagents51,13. The former reaction may also be accomplished by employing the perfluoroalkylsilane, the aryl iodide and stoichiometric amounts of KF2. Trifluoromethylation may also be accomplished, in more modest yields, by decarboxylation of sodium trifluoroacetate in.the presence of Cul and an aryl iodide71. Stannylation has been accomplished of aryl halides by the use of h.o. stannylcyanocuprates (equation 50)72. 

A possible route to secondary perfluoroalkylcopper reagents may be a reaction between a copper(I) halide and a secondary perfluoroalkylsilver compound. The latter are easily prepared by the addition of silver fluoride to a perfluoroolefin in acetonitrile at 25°C 202) [Eq. (26)]. 

Some perfluoroalkylcopper compounds were preeipitated from... 

Perfluoroalkylcopper and perfluoroarylcopper compounds are noticeably more thermally stable than the corresponding alkyl and aryl compounds. Solutions of perfluoroalkylcopper compounds in DMSO or DMF are stable up to at least 120°C 200), whereas ether suspensions of alkylcopper compounds decompose at 0°C or below. Similarly, pure pentafluorophenylcopper tetramer decomposes at 210°C-220°C, and a sample has been kept in a Dry Ice chest for 5 years 32). However pure phenylcopper can be kept for no more than a few days, even under nitrogen 73). Solutions of pentafluorophenylcopper reagents containing metal halides in THF have been refluxed for 5 days or more without decomposition (97, 144). Other stable perhaloarylcopper reagents are those in which the aryl moiety is perfluoro(p-phenoxyphenyl) (96), pentachlorophenyl, and 2,3,5,6-tetrachloropyridyl 144), none of which... 

The reaction of perfluoroalkylcopper compounds, prepared in situ from the perfluoroalkyl iodide and copper, with ip -hybridized organic halides [Eq. (73)] in refluxing pyridine utilizes the thermal stability of the intermediate copper compounds and their failure to react with sp -hybridized halides (29, 30). 

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