Trifluoromethanesulfonic esters

Various sources of fluoride ion have been investigated, of which highly nucleophilic tetraalkylammonium fluorides ate the most effective Thuf, fluoro alkyl halides and N (fluoroalkyl)amines are efficiently synthesized by treatment of the corresponding trifluoromethanesulfonic esters with tetrabutylammonium fluoride trihydrate in aprotic solvents [5fl] (equation 34) The displacement reactions proceed quantitatively at room temperature within seconds, but tail with hydrogen fluoride-pyridine and give reasonable yields only with hydrogen fluo ride-alkylamine reagents... 

Trifluoromethanesulfonate esters ( triflates ) of allyl alcohol and its derivatives are very reactive and undiluted samples must be stored in vented containers at — 78° C. A chilled sample of allyl triflate in a sealed ampoule exploded on being allowed to warm to ambient temperature. The esters react violently with aprotic solvents such as DMF or DMSO. Individually indexed compounds are ... 

Enolization of ketonic substrates can be carried out under far milder conditions if the dialkylboryl trifluoromethanesulfonate esters 59 (eq. [24]) are employed in the presence of hindered tertiary amines (eq. [43]) (6,63). At low temperatures (-78 0°C),... 

Reductive cyclization of o-nitrophenylacetic acids is a very general method of oxindole synthesis (see Section 3.06.2.1.1 for the application of this method to indoles in general). The main problem is efficient construction of the desired phenylacetic acid. One method involves base-catalyzed condensation of substituted nitrotoluenes with diethyl oxalate followed by oxidation of the 3-arylpyruvate (equation 200) (63CB253). Nucleophilic substitution of o-nitrophenyl trifluoromethanesulfonate esters, which are readily prepared from phenols, by dimethyl malonate provides another route (equation 201) (79TL2857). 

Cesium fluoride, 68 Sulfonic acids and esters p-Toluenesulfonate esters p-Toluenesulfonyl chloride, 313 Trifluoromethanesulfonate esters N-Phenyltrifluoromethanesulfonimide, 142... 

Recently trifluoromethanesulfonic esters of inositols have been employed in the SN2-type substitution reaction, among which several reports are described here. In order to prepare D-chiro-inositol 125 and its derivatives, the former of which was identified as a constituent of a putative insulin mediator for rat liver, readily available myo-inositol triflates 267 were converted to chiro-forms 268 by the Sn2 reaction with various nucleophiles (Scheme 5-2).93 On the other hand, the triflates 269 derived from quebrachitol 260... 

Reaction with Alcohols and Phenols. The reaction of alcohols and phenols with triflic anhydride (Tf20) at 0°C in the presence of a base (usually Pyridine) in an inert solvent (usually dichloromethane) for 2-24 h affords the corresponding reactive trifluoromethanesulfonate esters (triflates). When triflic anhydride and pyridine are combined, the pyridinium salt forms immediately and normally precipitates out from the reaction mixture. Nevertheless, the salt is an effective esterifying agent, reacting with the added alcohol to give triflates in high yields (eq 1). ... 

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