Fluorination reagents for

Conversion of tertiary formamides into A-(trifluoromethyl)amines involves a reduction-oxidation process in which sulfur tetrafluoride is reduced to elemental sulfur.175 Both /V,/V-dial-kyldifluoro(phenyl)methy la mines and A -(trifluoromethyl)amines are mild fluorinating reagents for the replacement of hydroxy groups by fluorine.176... 

The commercially available diethylaminosulfur trifluoride, Et3NSF, (DAST), was shown to be a particularly convenient fluorination reagent (for a review, see [259]). The sequence shown here was used for the preparation of a,a-difluoroethers [138],... 

The hydrogen fluoride/pyridinc [pyridinium poly(hydrogen fluoride)] reagent, which is commercially available, was introduced as a fluorinating reagent for secondary and tertiary alcohols by Olah in 1973. However, the reagent was used as early as 1960 by Bergstrom for the synthesis of fluoro steroids. 

The use of solid l-fluoropyridin-2(l//)-one (9) as an electrophilic fluorinating reagent for enamines requires no special safety devices. ... 

Xenon difluoride is a better fluorinaling reagent for vinyltin compounds than cesium fluoroxysulfate (compare entry 1 in Tables 1 and 2). Besides this, cesium fluoroxysulfate (which can be prepared from elemental fluorine and cesium sulfate) is known to be shock sensitive and to undergo detonation upon hcaling. However, cesium fluoroxysulfate is the alternative choiee in the ease of some vinyltin compounds, such as 2- and 3-(trimethylstannyl)indolcs (Table 2, entries 5 7), whose reactions with xenon difluoride are not effective. 

The reaction proceeds with inversion of configuration. The reagent has been compared with other fluorinating reagents for the preparation of 2-fluorooctane. In this case, the highest yield (40%) is obtained with KF or diethyl(2-chloro-l,l,2-trifluoroethyl)amine (5, 26), but the highest optical yields are obtained with 1 (100%) and (diethylamino)sulfur trifluoride (97.6%, 6, 183-184). ... 

Coupling is not usually performed with lithium. p Not a viable fluorination reagent for carbon chemistry. q Ether cleavage is performed with HI, not HF. r Deprotonation of CH adjacent to oxygen can occur. 

Iodine pentafluoride, IF5, has found some synthetic application as a powerful fluorinating reagent [1311, 1312]. For example, IF5, in combination with pyridine and HF, can be used as a fluorination reagent for the introduction of fluorine atoms to the a-position in sulfldes (Scheme 3.365) [1313]. A similar fluorination of sulfldes using IF5 without pyridine and HF affords a mixture of polyfluorinated products [1314]. 

Lee E, Kamlet AS, Powers DC, Neumann CN, Boursalian GB, Furuya T, Choi DC, Hooker JM, Ritter T (2011) A fluoride-derived electrophilic late-stage fluorination reagent for PET imaging. Science 334 639-642... 

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