Alcohols monofluoro

The reaction of 1,2-diols with sulfur tetrafluoride leads to fluorosulfites, which on hydrolysis, give monofluoro alcohols [555] (equation 74)... 

The elimination of water from a fluorinated compound generally follows a reaction path similar to that of its nonfluorinated counterpart, although the presence of the highly electronegative fluorine atoms may have unexpected effects Various monofluoro alcohols can be dehydrated via their tosyl esters at 75 C by using potassium rert-butoxide [80] (equation 50)... 

The most general and useful application of sulfur tetrafluoride is replacement of carbonyl oxygen and hydroxy groups by fluorine. The reaction has broad scope and is effective with all carbonyl and hydroxy compounds. Alcohols are converted into monofluoro derivatives 1, aldehydes, ketones and quinones into gew-difluoro compounds 2 and 3, and carboxylic acids, acid anhydrides, acid halides and amides into trifluoromethyl compounds 4. 

Similarly alcohols readily react with PFCI2 to produce monofluoro-phosphites (55, 67, 205), while amino alcohols and amino thiols afford cyclic compounds (179, 203). 

O.l-l.O Aliphatic Alcohols, Ketones, Aldehydes, Amines, Nitriles Monofluoro- and Chloro- Compounds. -OH -NHz O -CN Halogens... 

Monochloro, monofluoro, aliphatic alcohols, ketones Dichlori, difluoro, monobromo derivatives Trichloro, anhydrides Monoiodo, dibromo, nitro derivatives Diiodo, tribromo, polychlorinated aromatics... 

Later, different amino alcohols were used for the same type of difluoro Refor-matsky reactions [158], and the extension to prochiral ketones was reported recently [171]. In addition, protocols for monofluoro Reformatsky reactions were disclosed that lead to products with moderate diastereoselectivity but remarkable enantioselectivity for the individual diastereomers [172]. All these protocols have in common that they are not catalytic and the chiral additive needs to be applied at least in stoichiometric amounts. Thus, it seems that protocols for an enantioselective catalytic difluoro Reformatsky as well as difluoro aldol reaction are still missing. 

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