Pyridinium polyfhydrogen fluoride

OLYCOSYL fluorides (Diethylamino)suifur trifluoride. Pyridinium polyfhydrogen-fluoride). 

The hydrogen fluoride/pyridinc [pyridinium polyfhydrogen fluoride)] reagent, which is commercially available, was introduced as a fluorinating reagent for secondary and tertiary alcohols by Olah in 1973.178 However, the reagent was used as early as 1960 by Bergstrom for the synthesis of fluoro steroids.179... 

Only a few examples of reactions of oximes and oxime methyl ethers with iodine monofluoride5 and bromine trifluoride have been reported (Table 6. entries 6, 8 -12). The yields in these reactions are lower, except in the case of the activated aryl ketone (entry 12). Furthermore, iodine monofluoride does not react with oxime methyl ethers, due to the low basicity of the nitrogen atom. Therefore, these reagents are not good alternatives to the reaction utilizing nitrosonium tetrafluoroborate and pyridinium polyfhydrogen fluoride). 

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