Trifluoromethanesulfonic acid anhydride

Trifluoromethanesulfonic acid anhydride, bp 84°C, is prepared by refluxing the acid over an excess of phosphorous pentoxide (18,26). The anhydride reacts instantaneously with ammonia or amines to form trifluoromethanesulfonamides. The anhydride reacts with most polar organic solvents. 

A. Trifluoromethanesulfonic Anhydride. To a dry, 100-ml., round-bottomed flask are added 36.3 g. (0.242 mole) of trifluoromethane-sulfonic acid (Note 1) and 27.3 g. (0.192 mole) of phosphorus pentoxide (Note 2). The flask is stoppered and allowed to stand at room temperature for at least 3 hours. During this period the reaction changes from a slurry to a solid mass. The flask is fitted with a short-path distilling head and then heated first with a stream of hot air from a heat gun and then with the flame from a small burner. The flask is heated until no more trifluoromethanesulfonic anhydride distills, b.p. 82-115°. The yield of the anhydride, a colorless liquid, is 28.4-31.2 g. (83-91%). Although this product is sufficiently pure for use in the next step of this preparation, the remaining acid may be removed from the anhydride by the following procedure. A slurry of 3.2 g. of phosphorous pentoxide in 31.2 g. of the crude anhydride is stirred at room temperature in a stoppered flask for 18 hours. After the reaction" flask has been fitted with a short-path distilling head, it is heated with an oil bath to distill iD.7 g. of forerun, b.p. 74—81°, followed by 27.9 g. of the pure trifluoromethanesulfonic acid anhydride, b.p. 81-84° (Note 3). 

A. 3-Butyn-l-yl Trifluoromethanesulfonate. A 500-ml., three-necked flask is fitted with a mechanical stirrer, a pressure-equalizing dropping funnel, and a stopper. The system is flushed with nitrogen through a gas-inlet tube attached to the top of the funnel. To 150 ml. of dry methylene chloride (Note 1) in the flask is added 75 g. (0.27 mole) of trifluoromethanesulfonic acid anhydride (Note 2), and the solution is cooled to —40°. After addition of 14.5 g. (0.14mole) of finely powdered anhydrous sodium carbonate (Note 3), 15 g. (0.21 mole) of 3-butyn-l-ol (Note 4) is added dropwise over a 20-minute period to the well-stirred reaction mixture maintained at —40° to —55°. Stirring is continued at —30° for 2 hours and then at 0° for another hour, and finally the... 

Trifluoromethanesulfonic acid anhydride hinds to the carboxyl oxygen of both tertiary amides (A in Figure 7.5) and of the primary amides just discussed (A in Figure 7.4). However, the... 

Activation of a side-chain primary alcohol function with trifluoromethanesulfonic acid anhydride led to exclusive C-alkylation resulting in a cationic ring closure to afford the tetrahydroindoles (A)-584 (Equation 140) <2004T1197>. When R = H the N-Tf-substituted compound (5)-584 was formed as a side product in 18% yield. It was important to conduct the reaction in the presence of 4-methyl-2,6-di-/-butylpyridine as a sterically demanding and effective proton scavenger. 

Conversion of alcohols to sulfonate esters is a way of labilising them to nucleophilic substitution and elimination. The common leaving groups are arenesulfonates, particularly p-toluenesulfonate (tosylate), methanesulfonates (mesylate) and trifluromethanesulfonate (triflate) they are introduced by reaction of the acid chlorides (or, in the case of the trifluoromethanesulfonates, acid anhydrides) in a basic solvent such as pyridine. Traditionally, the reactions are carried out in pyridine as solvent, but both this solvent and the liberated... 

Condensation of ketones with two mole equivalents of a nitrile in the presence of trifluoromethanesulfonic acid anhydride is a nsefnl method for the production of a limited range of pyrimidines, where the substituents at C-2 and C-4 are identical. ... 

Phenylendiamine reacts with formic acid at 100°C to give benzimidazole in a yield of over 80%. A-Monosubstituted o-phenylenediamines react with other carboxylic acids more slowly, necessitating the addition of hydrochloric or phosphoric acid. A mixture of trifluoromethanesulfonic acid anhydride and triphenylphosphane oxide in dichloromethane is a very efficient dehydrating agent [122]. 

Aniline allowed to react at -78° with trifluoromethanesulfonic acid anhydride and triethylamine in methylene diloride -> N-phenyltriflamide. Y 97%. - The protective group can be removed by reduction. F. e. and triflating agent, also Gabriel-type synthesis of prim, amines from halides via triflamides, s. J. B. Hendrickson and R. Bergeron, Tetrah. Let. 1973, 3839. 

Keteniminium salts undergo [2-1-2] cycloaddition reactions with unreactive olefins, such as ethylene, cyclopentene, cyclohexene and styrol to give cyclobutane ammonium salts 23, which are readily hydrolyzed to give cyclobutanones 24. Likewise, reaction with acetylene derivatives affords cyclobutenylidene ammonium salts 25, which are also readily hydrolyzed to give the cyclobutenones 26. Some of the [2-1-2] cycloadducts obtained from keteniminium salts and olefines are shown in Table 4.17. The keteniminium salts are easily synthesized from suitable dimethylamides and phosgene, or trifluoromethanesulfonic acid anhydride. The reaction of the amide with phosgene generates a chloro compound 21, which is in equilibrium with the ketenimine salt 22. 

The isolation of the non-cyclic amino(aryl)carbenes and amino(alkyl)car-benes demonstrated that singlet carbene centers can be sufficiently stabilized by only one a-nitrogen atom. In 2005, Bertrand and co vorkers succeeded in preparing the first cyclic alkyl(amino)carbenes (CAACs, Scheme 1.15). The precursor for CAAC 123 was obtained from an imine by deprotonation with LDA (LDA = lithium diisopropylamide) and subsequent reaction with l,2-epoxy-2-methylpropane to give 121, which was converted into cyclic aldirain-ium salt 122 by reaction with trifluoromethanesulfonic acid anhydride. Deprotonation of 122 with LDA afforded CAAC 123 as a colorless solid (Scheme 1.15). 

Alkyl esters of trifluoromethanesulfonic acid, commonly called triflates, have been prepared from the silver salt and an alkyl iodide, or by reaction of the anhydride with an alcohol (18,20,21). Triflates of the 1,1-dihydroperfluoroalkanols, CF2S020CH2R can be prepared by the reaction of perfluoromethanesulfonyl fluoride with the dihydroalcohol in the presence of triethylamine (22,23). Triflates are important intermediates in synthetic chemistry. They are among the best leaving groups known, so they are commonly employed in anionic displacement reactions. 

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). 

Trifluoromethanesulfonic (triflic) anhydride is commercially available or can be prepared easily by the reaction of triflic acid with phosphorus pentoxide [66] This moderately hygroscopic colorless liquid is a useful reagent for the preparation of various organic derivatives of triflic acid A large variety of organic ionic triflates can be prepared from triflic anhydride A recent example is the preparation of unusual oxo-bridged dicatiomc salts of different types [SS, 89, 90, 91, 92, 93] (equations 38-44) Stabilized dication ether salts of the Huckel aromatic system and some other systems (equations 38 and 39) can be prepared in one step by the... 

Acylation of 4 with acid anhydrides in the presence of trifluoromethanesulfonic acid389 gives monoacyl derivatives 9. 6-Acetyltrithiadiazepine 9a undergoes bromination to give 6-acetyl-7-bromo-l,3/.4,5,2,4-trithiadiazepine (10) nitration gives a mixture of the nitro derivative 11 and the dcacctylated compound 5.387... 

C[iH4F,iN20gS2 157875-58-6) see Imiquimod trifluoromethanesulfonic acid triethylsilyl ester (C7Hi5F303SSi 79271-56-0) see Tacrolimus trifluoromethanesulfonic anhydride (C2F(,05S2 358-23-6) see Imiquimod Zanamivir... 

Trifluoromethanesulfonic anhydride is purchased from the Aldrich Chemical Company, Inc., and used as received. It may also be prepared from trifluoromethanesulfonic acid.3... 

The third procedure illustrated by this preparation involves the reaotion of ketones with trifluoromethanesulfonic anhydride in a solvent such as pentane, methylene chloride, or carbon tetrachloride and in the presence of a base such as pyridine, lutidine, or anhydrous sodium carbonate.7-11,15 This procedure, which presumably involves either acid-catalyzed or base-catalyzed enolization of the ketone followed by acylation of the enol with the acid anhydride, has also been used to prepare other vinyl sulfonate esters such as tosylates12 or methanesulfonates.13... 

Trifluoromethanesulfonic anhydride from Fluka AG was stirred over phosphorus pentoxide for 18 hr and distilled. It can also be prepared from trifluoromethanesulfonic acid (Fluka AG) according to the procedure described in Organic Syntheses. ... 

The acylation of dibenzofuran is carried out under the usual Friedel-Crafts conditions with an acid chloride or an acid anhydride in the presence of aluminum chloride. Dibenzofuran on treatment with 2-trifluoromethane-sulfonyloxypyridine and benzoic acid in boiling trifluoroacetic acid produces the 2-benzoyl derivative in 75% yield. The species responsible for benzoyla-tion is probably a mixed anhydride of trifluoromethanesulfonic acid and benzoic acid. Dibenzofuran on treatment with 2-benzoyloxypyridine and trifluoroacetic acid also produces the 2-benzoyl compound (21%). The kinetics of the acetylation of dibenzofuran with acetyl chloride and aluminum chloride in nitroethane at 25"C have been studied. Only the 2-acetyl compound was detected by the methods used. The rate obtained is in general agreement with the studies mentioned previously. The rate of acetylation of diphenyl ether relative to toluene was 138 (+ 16), whereas that of dibenzofuran was 5.9 ( 0.3). In contrast, the benzoylation of dibenzofuran with benzoyl chloride in the presence of aluminum chloride in nitrobenzene at... 

A non-aqueous method for the titration of procaine and other drugs using trifluoromethanesulfonic acid was reported by Zakhari and Kovar [88]. Solutions of procaine hydrochloride in anhydrous acetic acid, acetic anhydride, their mixture, or in acetone, was titrated with an acetic acid solution of 0.1 M trifluoromethanesulphonic acid or 0.1 M perchloric acid. Titration was effected in the presence or in the absence of mercurous acetate. The end point was detected visually (using crystal violet as indicator) or potentiometrically. 

Acetic acid, trifluoro-, anhydride with trifluoromethanesulfonic acid)... 

Amides of trifluoromethanesulfonic acid (triflamides) can be prepared by the reaction of the corresponding amines with triflic anhydride The most applicable in organic synthesis are iV-phenyltriflamides, which can be used as mild and selective Inflating reagents [110, lll ... 

Triethynylantimony, 2118 Triethynylarsine, 2089 1,3,5-Triethynylbenzene, 3437 Triethynylphosphine, 2117 Triferrocenylcyclopropenium perchlorate, 3879 Triflic acid , see Trifluoromethanesulfonic acid, 0374 Trifluoroacetamide, 0700 Trifluoroacetic acid, 0661 Trifluoroacetic anhydride, 1362 f 1,1,1-Trifluoroacetone, 1097... 

The total synthesis of mniopetal E (5) was achieved in a six-step sequence from the cycloadduct 125 (Scheme 21). The treatment of 125 with trifluoromethanesulfonic anhydride (Tf20) afforded triflate 129. Elimination of trifluoromethanesulfonic acid to introduce a double bond was accomplished in 2,6-lutidine at 100 °C, giving 130 in 84% yield. Deprotection of TBDPS ether was followed by Parikh-Doering oxidation of the resulting 131 by the same procedure used in the case of 127. Taking advantage of the electron-rich double bond between C-l... 

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