Trifluoromethanesulfonic acid methyl ester

Synonyms Methanesulfonic acid, trifluoro-, methyl ester Trifluoromethanesulfonic acid, methyl ester Empirical C2H3F3O3S Properties Colorless to brn. liq. sol. in 95% ethanol insol. in water reacts exothermically with DMSO m.w. 164.10 sp.gr. 1.450 (20/4 C) b.p. 94-99 C flash pt. 38 C ref. index 1.3244 (20 C) Toxicology Toxic by inh., ing., skin contact corrosive causes burns extremely destructive to tissues of eyes, skin, mucous membranes, upper respiratory tract risk of irreversible effects inh. may cause spasm, inflamm./edema of larynx/bronchi, chem. pneumonitis, pulmonary edema may cause burning... 

See Methyl trifluoromethane sulfonate Trifluoromethanesulfonic acid triisopropylsilyl ester. See Triisopropylsilyl trifluoromethane sulfonate... 

Esters of / fZ-amyl alcohol can be obtained by acylation of 2-methyl-2-butene in the presence of trifluoromethanesulfonic acid (44). The esters produced, in high yields, from reaction of amyl alcohols with carboxyHc anhydrides, are used as intermediates for preparation of pyryflum salts (45,46) and alkaloids (47). Tria2oles prepared by acylation of 3-methyl-1-butanol are useful as herbicides (48). 

Methyl triflate Methyl trifluoromethanesulfonate Methanesulfonic acid, trifiuoro-, methyl ester (8,9) (333-27-7)... 

Pyruvate ketals can be synthesized [161] by direct condensation of a pyruvate ester with a diol in the presence of a Lewis acid, but this is less preferred because of the electron-withdrawing effect of the adjacent carboxylate group [162,163]. Therefore, several indirect methods for the acetalization have been introduced including condensation with pyruvate derivatives [164,165] or generation of the carboxylate group by oxidation of a suitable precursor [166,167,168,169]. A more efficient route to pyruvic acid acetals starts from silylated diols [170] or by the reaction between diols and methyl pyruvate dialkyl dithioacetal [171,172] activated by methyl triflate, dimethyl(methylthio)sulfonium trifluoromethane sulfonate (DMTST), nitroso tetraflu-oroborate (NOBF4), S02Cl2-trifluoromethanesulfonic acid, or Al-Iodosuccinimide (NIS) and trifluoromethanesulfonic acid [173] (O Scheme 24). 

A variant of the preceding pathway has been described in which the methyl ester of (275) on treatment with a small amount of cupric trifluoromethanesulfonate in methylene chloride under oxygen for several hours affords (9) <90CC45i>. The yields of (9) are similar to those previously obtained by acid catalysis which suggests that adventitious acid, rather than cupric salt, may have been responsible for the result. 

Similarly, the scope of trifluoromethanesulfonic acid 6-methyl-pyridazine-3-yl ester as a coupling partner for biaryl synthesis via palladium catalyzed Suzuki and Stille coupling conditions has been reported (Equations 21 and 22) [25]. 

One-carbon Homologation of Carboxylic Acids. l-[(Tri-methylsilyl)methyl]benzotriazole converts benzoyl chlorides to the corresponding (benzotriazol-l-yl)methyl aryl ketones in high yields (see eq 1). Treatment with triflic anhydride and 2,6-lutidine in CH2CI2 converts these ketones into their enolate triflates in 83-95% yields (eq 4). In the subsequent steps, the triflates are treated with sodium methoxide and then with ethanolic HCl to afford ethyl esters of the corresponding arylacetic acids in 89-98% yields (eq 5). The proposed reaction mechanism involves elimination of trifluoromethanesulfonic acid with sodium methoxide and final alcoholysis of the obtained l-(arylethynyl)benzotriazole intermediates with ethanolic HCl. A comparable classical method for one-carbon homologation of carboxylic acids, the Amdt-Eistert reaction, involves difficult to handle diazomethane and Q -diazoketones. ... 

The combination of a secondary benzyl alcohol with Hf(OTf)4 in nitromethane was a highly effective secondary benzylation system. Secondary benzylation of carbon (aromatic compounds, olefins, an enol acetate), nitrogen (amide derivatives), and oxygen (alcohols) nucleophiles was carried out with a secondary benzyl alcohol and 1 mol % of Hf(OTf)4 in the presence of water. Secondary benzyl alcohols and nucleophiles bearing acid-sensitive functional groups (e.g.,icri-butyldimethylsilyloxy and acetoxy groups and methyl/benzyl esters) could be used for alkylation. Hf(OTf)4 was the most active catalyst for this alkylation, and trifluoromethanesulfonic acid (triflic acid, HOTf) also proved to be a good catalyst. In such cases, the catal)fiic activity of metal triflates and HOTf increased in the order La(OTf)3 [Pg.346]

The rapid aminolysis of cobalt(llI)-chelated glycine esters in aprotic solvents (Scheme 10 N4 = (en)2 or trien, R = Me, Et, R = H, CHR"C02Et) could be of value in peptide synthesis. The cobalt atom acts as both an N-protecting and an activating group. The synthesis of the chelated amino acid esters has presented some difficulties.207 A recent paper208 describes the use of methyl trifluoromethanesulfonate for the alkylation of chelated amino acids using dry trimethyl phosphate... 

It has been estimated that vinyl cation, CH2=CH, lies between ethyl cation and methyl cation in its stability. The intermediacy of substituted vinyl cations in solvolysis reactions has been demonstrated, but no evidence has yet been presented for their direct observation by NMR. Even the addition of stabilizing substituents such as methoxyphenyl has failed to yield observable vinyl cations. Vinyl cations are, however, intermediates in solvolysis reactions involving very good leaving groups, specifically trifluoromethanesulfonates (triflates). The products of such reactions are allenes, acetylenes, and vinyl esters. For both trifluoroacetic acid and acetic acid solvolysis the vinyl esters are mixtures of Z and E isomers, ruling out a stereospecific substitution." ... 

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