Perfluoroalkyl generation

Rh-catalysed intramolecular insertion into thiophene. 59, 204 cycloaddition to uracils, 55, 1% Carbene, 5,6-cycloadduct with 2H-thiopyran, 59, 225 Carbenes, a-keto-perfluoroalkyl-, generation, trapping. 60, 40 Carbenes, Fischer, reaction with N-(hexafluoroisopropylidene) amides,... 

Additions of halogen fluorides to the more electrophilic perfluonnated olefins generally require different conditions Reactions of iodine fluoride, generated in situ from iodine and iodine pentafluoride [62 102 103, /05] or iodine, hydrogen fluoride, and parapeiiodic aud [104], with fluormated olefins (equations 8-10) are especially well studied because the perfluoroalkyl iodide products are useful precursors of surfactants and other fluorochemicals Somewhat higher temperatures are required compared with reactions with hydrocarbon olefins Additions of bromine fluoride, from bromine and bromine trifluonde, to perfluonnated olefins are also known [lOti]... 

The monofluoromethylene group and difluoromethyl group m 1H perfluoro-alkanes and -cycloalkanes are oxidized at the C-H bond to perfluoroalkyl and perfluorocycloalkyl fluorosulfates by anodic oxidation m fluorosulfonic acid [J, 4] Two modifications of the method are used ox idation by fluorosulfonyl peroxide generated pnor to the reaction [J] (equation 2A) and direct electrolysis m the acid [i, 4] (equabons 2B and 3)... 

Sodium nitrite in dimethylformamide acts as a nucleophile and reacts with perfluoropropene to generate a perfluoroalkyl nitrite anion The intermediate carbanion undergoes intramolecular nitrosation with loss of carbonyl difluoride to give tnfluoroacetic acid upon hydrolysis [5] (equation 6)... 

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

Perfluoroalkyl carbanions, generated by reversible nucleophilic addition of a fluoride anion to fluoroalkenes, react with dry benzenediazonium chloride in dimethyl formamide, giving phenylazoperfluoroalkanes in 41-53% yield (Dyatkin et al., 1972). The dianion obtained from 1,2-dinitrobenzene with dipotassium cyclo-octatetraenide reacts in a complex way with arenediazonium salts, forming 4-aryl-azo-2-nitrophenol in 46-58% yield (Todres et al., 1988). 

The addition of perfluoroalkyl iodides to simple olefins has been quite successful under aqueous conditions to synthesize fluorinated hydrocarbons.119 In addition to carbon-based radicals, other radicals such as sulfur-based radicals, generated from RSH-type precursors (R = alkyl, acyl) with AIBN, also smoothly add to a-allylglycines protected at none, one, or both of the amino acid functions (NH2 and/or CO2H). Optimal results were obtained when both the unsaturated amino... 

Direct electrochemical reduction of perfluoroalkyl halides generates perfluoroalkyl radicals or anions depending on the electrolytic conditions and starting halides. Calas et al. have performed the electrocatalytic addition of perfluoroalkyl iodides to 3-hydroxyalkynes in aqueous KCI emulsion using a... 

In contrast to the direct reduction as described above, the indirect electrochemical reduction of perfluoroalkyl halides is a versatile and novel method for generating perfluoroalkyl radicals selectively. Saveant et al. have demonstrated many successful examples. Using terephthalonitrile as a mediator, the indirect reduction of CF3Br in the presence of styrene leads to the dimer of the radical adduct obtained by the attack of CF on styrene. On the other hand, in the presence of butyl vinyl ether, the mediator reacts with the radical adduct obtained by the attack of CF3. on the olefin (Scheme 3.4) [14]. 

The dimerization of vinyl carbenoids, generated from the precursors 16, allows the building of butatrienes with perfluoroalkyl groups (RF) [30, 31]. The products 17 are obtained as E-Z mixtures. 

Spruce meal and beech blocks were modified by using a mixture of perfluoroalkyl ethanol and MDI. Improved dimensional stability and water repellency were reported (Engonga etal., 1999). In order to avoid the handling problems associated with the use of most isocyanates, the generation of isocyanates within the wood by thermal rearrangement of acyl azides has been studied (Gdrardin etal., 1995) (Figure 4.8). This is potentially a... 

Additions of perfluoroalkyl groups generated from perfluoroalkyl iodides (Rpl) and perfluoroacyl peroxides [RpC(0)00(0)CRp] have also been carried out [50]. Another usable source of CEj radicals is the stable [(CF3)2CF]2 CCF2CE3 radical (Scheme 6.8) [51]. As with alkyl radical additions, ESR spectroscopic investigations... 

Similarly, perfluoroalkyl lithium reagents, generated from the reaction of... 

Perfluoroalkyl lithium reagents undergo reactions typical of their hydrocarbon analogs. For example, perfluoroalkyl lithium reagents generated in situ from perfluoroalkyl iodides and alkyl lithiums reacted readily with aldehydes and ketones to yield the corresponding secondary and tertiary carbinols, and with esters to give either ketones or tertiary carbinols [12]. No 1,4-addition product is observed when a,/ -unsaturated ketones and esters are employed. 

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