Trifluoromethyl anion triflates

Within a series of non-haloaluminate ionic hquids containing the same cation species, increasing anion mass corresponds to increasing ionic hquid density (Tables 3.2-1 and 3.2-3). GeneraUy, the order of increasing density for ionic hquids composed of a single cation is mesylate tetrafluorborate < trifluoromethyl acetate < triflate < heptafluoropropyl acetate < bis(trifuoromethylsulfonyl)amide. 

When the reaction between a-trifluoromethyl sulfone 286 and paraformaldehyde was carried out in the presence of potassium carbonate, the vinyl sulfone was obtained quantitatively upon elimination of triflate anion. Such a deacylative methylenation was observed in the reaction between 8-ketosulfones 287 and 288 and paraformaldehyde ... 

After extensive experimentation, a simple solution for avoiding catalyst deactivation was discovered, when testing an Ir-PHOX catalyst with tetrakis[3,5-bis (trifluoromethyl)phenyl]borate (BArp ) as counterion [5]. Iridium complexes with this bulky, apolar, and extremely weakly coordinating anion [18] did not suffer from deactivation, and full conversion could be routinely obtained with catalyst loadings as low as 0.02 mol% [19]. In addition, the BArp salts proved to be much less sensitive to moisture than the corresponding hexafluorophosphates. Tetrakis (pentafluorophenyl)borate and tetrakis(perfluoro-tert-butoxy)aluminate were equally effective with very high turnover frequency, whereas catalysts with hexafluorophosphate and tetrafluoroborate gave only low conversion while reactions with triflate were completely ineffective (Fig. 1). 

To increase the solubility of the aggregates formed, the large lipophilic TFPB anions (TFPB = tetrakis-(3,5-bis-(trifluoromethyl)-phenyl)-borate) were used instead of the triflate anions [66-68]. The zinc salt [Zn(NCMe)6][TFPB]2 50 was obtained by reaction of zinc bromide with Ag(TFBP) in acetonitrile under exclusion of light. Addition of tetrahydrofuran-dg to a mixture of the cavitand 49 and the zinc salt 50 gave the coordination cage 51 after keeping the reaction mixture at 60 °C for 1 h (Fig. 16). 

An example of cleavage ot the sulfur-oxygen bond in trifluoromethane-sulfonic ester has been reported Trifluoromethyl triflate reacts with neutral or anionic nucleophiles with elimination of carbonyl difluonde and formation of trifluoromethanesulfonyl fluoride [57] (equation 37) The mechanism of this reaction involves elimination of fluoride ion, which is a chain earner in the substitution of fluorine for the trifluoromethoxy group... 

The solubility of the catalyst salt is improved by the use of 3,5-bis(trifluoromethyl)phenylborate or triflate anions. Unsaturated fatty acids can be reduced in the same way.173 Hydrogenations in sc carbon dioxide can be more selective than in the gas phase while using 35 times less catalyst.174 Cyclohexene was reduced with hydrogen and a polysilox-ane-supported palladium catalyst in in a continuous-flow reactor in 95-98% yields. Epoxides, oximes, nitriles, aldehydes, ketones, and nitro compounds can also be reduced. By varying the temperature, the products from the reduction of nitrobenzene can be selected from aniline, cyclo-hexylamine, dicyclohexylamine, and cyclohexane. In the... 

Marrec et al. [34] used trifluoromethyl triflate (TFMT) as a generator of trifluoro-methoxy anion when activated by fluoride anions. Commercially available flnorides (silver fluoride and n-tetrabutylammonium triphenyldifluorosihcate), combined with TFMT, allow a simple generation, in situ, of silver and n-tetrabntylammoninm trifluoromethoxides which were able to react with electrophihc snbstrates. Silver trifluoromethoxide, which is usually more efficient than n-tetrabntylammoninm trifluoromethoxide, converts, under mild conditions, primary ahphatic bromides and iodides as well as primary and secondary benzylic or allylic bromides. Several trifluoromethyl ethers, which could be valuable building-blocks, were prepared in such a way (Scheme 7). 

Buchwald reported the same process but as applied to vinyl triflates and nonaflates. In this case, TMSCF3 or TESCF3 was combined with KF or RbF to provide the CF3 anion, which would transfer on to the metal centre. Liu reported the palladium catalyzed indole C-2 trifluoromethylation which is proposed to proceed through a Pd(ii)/Pd(iv) cycle whereby bisacetox-yiodobenzene serves as oxidant.Also reported was the bis-functionalisa-tion of alkenes, specifically resulting in the formation of trifluoromethylated oxindoles (Scheme 15.115). It was found that addition of ytterbium triflate served to increase yields. 

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