Trifluoromethanesulfonyl sulfones

An example of cleavage ol the sulfur-oxygen bond in trifluoromethane-sulfonic ester has been reported Tnfluororaethyl triflate reacts with neutral or anionic nucleophiles with elimination of carbonyl difluoride and formation of trifluoromethanesulfonyl fluoride [57] (equation 32) The mechanism of this reaction involves elimination of fluoride ion, which is a chain carrier in the substitution of fluorine for the trifluoromethoxy group... 

Other sulfonate derivatives are obtained by the use of trifluoromethanesulfonyl hypochlorite and hypobromite (CF3SO2OQ and CF3S020Br) in reactions with petfluoroalkyl halides and their derivatives [30. These reactions lead to the corresponding trifluoromethanesulfonate derivatives of alkanes (equation 28) (Table 11). The reaction proceeds with complete retention of stereochemistry at the carbon center [30]. 

The trifluoromethanesulfonyl (triflyl group) is one of the strongest electron-withdrawing groups and therefore is a versatile functionality for organic synthesis Trifluoromethyl sulfones have been prepared by using an electrophilic tnflyl source such as triflic anhydride or by displacing primary halides with a inflate salt... 

It has also been possible to prepare extremely stable triphenylphosphonium (trifluoromethanesulfonyl)methylide from chloromethyl trifluoromethyl sulfone and triphenylphosphine [6S] (equation 60)... 

Against this background it is important that—quite fitting in this still new millennium— the first catalytic Friedel-Crafts acylations of (still relatively electron-rich) aromatic compounds were reported (Figure 5.35). Trifluoromethane sulfonates ( triflates ) of rare-earth metals, e. g., scandium(III)triflate, accomplish Friedel-Crafts acylations with amounts of as little as 1 mole percent. Something similar is true of the tris(trifluoromethanesulfonyl)-methides ( triflides ) of rare-earth metals. Unlike conventional Lewis acids, the cited rare-earth metal salts can form 1 1 complexes with the ketone produced, but these are so unstable that the Lewis acid can re-enter the reaction. Whether this works analogously for the third catalytic system of Figure 5.35 is unclear. 

However, when considering the choice of ionic liquid it is worth noting that a number of the anions that are utilized in ionic liquids have already been investigated as dopants for conducting polymers using a conventional molecular solvent/electrolyte system. For example, the relative merits of the trifluoromethane-sulfonate [OTfp [37], hexafluorophosphate [PF6]- [38. 39], sulfonated aromatics [40, 41] and, particularly, bis(trifluoromethanesulfonyl)amide [NTf)] [37, 42-45] anions have been well studied and it may be pertinent to consider this research when selecting an ionic liquid for investigation. 

The synthesis of electron-deficient diene 285 was achieved by the Stille coupling of P-trifluoromethanesulfonyl-a,P-unsaturated sulfone (284) with a 3-stannyl-a,P-unsaturated ester (283) (Scheme 74).148 Similarly, the preparation of a diverse range of enantiomerically pure 1- and 2-sulfinyl dienes has been achieved via Stille coupling of halovinyl sulfoxides and vinyl stannanes.149,150 Enantiomerically pure 1- and 2-sulfinyl dienes have been used extensively in asymmetric Diels-Alder reactions.111... 

Aromatic sulfonic acid and perfluoroalkanesulfonic acids resins are widely used as ion-exchange resins in water treatment and multiple other industrial applications. In the form of membranes, they are routinely used in electrochemical cells, particularly in electroplating of metals and in battery applications. The lithium salts of trifluoromethanesulfonic acid and N-trifluoromethanesulfonyl trifluoromethanesulfonamide are both employed as electrolytes in secondary battery applications. 

An increase in the electron deficiency of the sulfonates, by replacement of a mesyl by a trifluoromethanesulfonyl group, induces an increase in the proportion of alkanes versus alcohols in the product mixture. Thus deoxysugars can be obtained in good yield, either by photolysis of the triflate derivatives in aqueous HMPA or reduction by sodium in liquid ammonia. The detosylation reactions of arenesulfonates and arenesul-fonamides do not always require PET processes. When the photolysis is carried out in solvents such as EtjO or MeOH, the alcohol can be recovered in high yields from arenesulfonates while a mixture of amine and ammonium tosylate is usually obtained from tosylamides. A mechanistic study of the reaction indicated that the bond initially cleaved is different in sulfonates and sulfonamides (Scheme 3). ... 

TABLE 27.2. Values of Conductivity (c), ESW, Melting Points with ILs in the Limit, Formula Weight and Density of V-Butyl-iV-Methyl Pyrrolidinium (PYRj4-l-) and V-Methoxyethyl-V-Methylpyrrolidinium (PYRj 2 y-l-)-Based ILs with Bis (trifluoromethanesulfonyl)imide (TFSI—) and Trifluoromethane Sulfonate (Tf—) Anions... 

Reaction with Arenes. Benzenesulfonyl bromide reacts readily with trifluoromethanesulfonyl derivatives, yielding the corresponding mixed anhydrides (eq 6) which have been used to convert arenes to aryl phenyl sulfones under Friedel-Crafts-type conditions. 

Other nitrogen nucleophiles can react efficiently with triflyl chloride. Below —30°C, 1,1-dimethylhydrazine was sulfonated to afford the corresponding trifluoromethanesulfonic hydrazide. In the azole series, the side chain of some 1,2,3-triazoles was functionalized with a trifluoromethanesulfonyl group (eq 10). When pentafluoroethanesulfonyl chloride was used in this transformation, a mixture of mono- and di-sulfonylated derivatives was... 

Alternate Name phenyl(trifluoromethanesulfonyl)acetylene phenylethynyl trifluoromethyl sulfone. 

This method is also useful for the synthesis of alkenyl-substituted trifluoro-methyl sulfone derivatives 91 (Scheme 2.55). Halogen-lithium exchange of iodo-methyltrimethylsilane with Bu Li, followed by addition of 0.5 equivalents of triflic anhydride, provides the a-silyl carbanion bearing a trifluoromethanesulfonyl group. Reactions of the a-silyl carbanion with aldehydes give the corresponding... 

Trifluoromethanesulfonyl chloride reacts with alcohols to form sulfonate esters. Would you expect the trifylates to be more or less reactive than the methanesulfonate esters ... 

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