Fluonnation of enolates

Selective fluonnation in polar solvents has proved commercially successful in the synthesis of 5 fluorouracil and its pyrimidine relatives, an extensive subject that will be discussed in another section Selective fluonnation of enolates [47], enols [48], and silyl enol ethers [49] resulted in preparation of a/phn-fluoro ketones, fieto-diketones, heta-ketoesters, and aldehydes The reactions of fluorine with these functionalities is most probably an addition to the ene followed by elimination of fluonde ion or hydrogen fluoride rather than a simple substitution In a similar vein, selective fluonnation of pyridmes to give 2-fluoropyridines was shown to proceed through pyridine difluondes [50]... 

Fluonnations of enolates with chiral reagent D (Table 3a) give moderate degrees of enantiomeric excess [67] (equation 43). 

Af-Fluorobis(trifluoromethanesulfonyl)imide is also effective in the mono-fluonnation of ester and amide enolates, and of neutral dicarbonyl compounds. Excellent stereoselectivity is observed [48, 80, 81] (equations 39-41)... 

The fluonnation of both mono and dinitro enolates proceeds well with perchloryl fluoride. The mononitro fluorinated intermediates have been used to develop fluorinated materials of general synthetic utility [III, 113] (equation 63)... 

Xenon difluonde [ 5], xenon difluondecomplexed with dialkyl suthdes [89], and xenon difluonde intercalated with graphite [90] are all effective reagents for the fluonnation of acids, enolates, or enols (Table 2)... 

Xenon difluoride reaction with nitro enolates provides a useful entry into a wide variety of fluonnated synthetic intermediates [91 92] (equation 52)... 

Silyl enol ethers are fluonnated in high yields with xenon difluoride [62 93, 94 95] Applications of this reaction to the preparation of fluonnated... 

Terminally unsaturated fluonnated alkenoic acids can be obtained from poly-fluorocycloalkenes by reaction with potassium hydroxide m rert-butyl alcohol [24] (equation 26) The use of a tertiary alcohol is critical because primary and secondar y alcohols lead to ethers of the cycloalkenes The use of a polar aprotic solvent such as diglyme generates enols of diketones [26] (equation 27) The compound where... 

Diacetato(l, 10-phenanthroline)palladium(II)-catalyzed transetherificatum of polyfluonnated alcohols with enol ethers leads to the corresponding fluonnated vinylic ethers [14] (equation 13)... 

The reactions of fluonnated esters and amides to form, respecuvely, enol ethers [47] and enamines [48] give high yields and are interesting synthetic transformations (equations 34 and 35) (Table 12)... 

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