Hydroxy fluorides

Imidocarbonyl Chloride Fluoride, Hydroxy-, Ethyl Phosphorobromidate Imidocarbonyl Chloride Fluoride, Hydroxy-, Ethyl Phosphorochloridate Imidocarbonyl Chloride Fluoride, Hydroxy-, Methyl Phosphorochloridate Imidocarbonyl Chloride Fluoride, Hydroxy-, 0-(2-Chloroethyl Phosphorochloridate)... 

Nucleophilic displacements on the sp2 carbon atom at C-5 of 1,2,4-thiadiazole (155 X = Cl) are plentiful. Chlorine, for example, may be displaced by fluoride, hydroxy, amino,... 

Halide derivatives may be fluorides, chlorides, or bromides. Fluorides are best prepared by the reaction of hydroxy groups with (diethylamino)sulfur trilluoride ( DAST M. Sharma, 1977) or of glycosyl thioethers with DAST/NBS (K.C. Nicolaou, 1990 B). The other halides are usually only introduced at the glycosidic position, where treatment with hydrogen chloride... 

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esteri nf methanesulfonic acid, p-toluenesidfonic acid, and especially trifluoromethane-sulfonic acid (tnflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... 

One of the most useful ways of introducing fluorine into organic compounds is the placement of the hydroxyl group in alcohols hydroxy compounds, and carboxylic acids Methyl alcohol reacts with anhydrous hydrogen fluoride at 100 500 °C in the presence of aluminum fluoride [60, 61], zinc fluoride [62] chromium fluonde [63], or a mixture of aluminum and chromium fluondes [64] to give a 20-78% yield of fluoromethane Attempted fluorinations of higher alcohols by this method failed [60]... 

Hydroxy-1-adamantanecarboxylic acid reacts exothermally with FAR to give 3-fluoro 1 adamantanoyl fluoride, which, after treatment with ammonium hydroxide, yields 3 fIuoro-1 adamantanecarboxamide [79] (equation 50)... 

Hexafluoropropyldiethylamine is a particularly useful reagent for conversion of secondary benzylic hydroxy esters into the corresponding secondary benzyl fluorides The reactions proceed with inversion of configuration and a high degree of stereospecificity [86, 87] (equation 53)... 

Fluormation of tertiary benzylic hydroxy esters with the Ishikawa reagent gives somewhat lower yields of fluorides because of the formation of dehydrated products, 2-aryl acrylates [87] (equation 54)... 

Qi-Hydroxy-17-methyltestosterone p-Toluene sulfonyl chloride Hydrogen fluoride... 

Fluorination. Direct fluorination of quinoline was accompanied by extensive fragmentation of the heteroring, but trifluoromethyl hypofluorite in trichlorofluoromethane at -70°C converted 5-fluoro-8-hydroxyquino-line into the 5,7-difluoro-8-hydroxy product (72JMC987). Quinoline, itself, was perfluorinated by fluorine and cobalt(III) fluoride (56JCS783), whereas cesium tetrafluorocobaltate at around 350°C converted it into a mixture of saturated polyfluoro compounds (82JFC413). It is much more satisfactory to introduce fluorine by nucleophilic methods. 

Organic Fluorides. Part IX. The Formation and Resolution of a-Hydroxy-a-trifluoromethylpropi-onic Acid, R. A. Darrall, F. Smith, M. Stacey, and J. C. Tatlow, /. Chem. Soc., (1951) 2329-2332. 

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