Trifluoromethanesulfonate anhydride

The Frasca method for obtaining 1-arylindazoles also involves a C(3)—C(3a) ring closure (67CJC697). It consists in the cyclization of p-nitrophenylhydrazones of ketones and aldehydes with polyphosphoric acid. The Barone computer-assisted synthetic design program has found several new methods for preparing indazoles (79MI40409). The selected method involves the transformation of jV, jV -diphenylhydrazides (596) into 1-phenylindazoles (597) by means of trifluoromethanesulfonic anhydride. The yields vary from 2% (R = H) to 50% (R = Ph). 

Amides and ureas may react also with trifluoromethanesulfonic anhydride to give resonance-stabilized dicarbonium salts [36] (equation 34). 

Diaryl sulfones can be formed by treatment of aromatic compounds with aryl sulfonyl chlorides and a Friedel-Crafts catalyst. This reaction is analogous to Friedel-Crafts acylation with carboxylic acid halides (11-14). In a better procedure, the aromatic compound is treated with an aryl sulfonic acid and P2O5 in polypho-sphoric acid. Still another method uses an arylsulfonic trifluoromethanesulfonic anhydride (ArS020S02CF3) (generated in situ from ArS02Br and CF3S03Ag) without a catalyst. ... 

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 Methanesulfonic acid, tri-fluoro-, anhydride (8, 9) (358-23-6)... 

Trifluoromethanesulfonates of alkyl and allylic alcohols can be prepared by reaction with trifluoromethanesulfonic anhydride in halogenated solvents in the presence of pyridine.3 Since the preparation of sulfonate esters does not disturb the C—O bond, problems of rearrangement or racemization do not arise in the ester formation step. However, sensitive sulfonate esters, such as allylic systems, may be subject to reversible ionization reactions, so appropriate precautions must be taken to ensure structural and stereochemical integrity. Tertiary alkyl sulfonates are neither as easily prepared nor as stable as those from primary and secondary alcohols. Under the standard preparative conditions, tertiary alcohols are likely to be converted to the corresponding alkene. 

The reactivity of dipyrrolylmethane 236 has similarly been exploited in its reaction with 4-dimethylamino-l,l,l-trifluoro-3-buten-2-one 239 and trifluoromethanesulfonic anhydride to generate the iminium ion 240 followed by hydrolysis to give the fluorinated product 241 in 56% yield (Scheme 16) <2003CHE776>. 

Symmetric triblock copolymers of the ABA type, where B was PTHF and A poly(2-methyl-2-oxazoline), PMeOx, were prepared by cationic polymerization with trifluoromethanesulfonic anhydride as a difunctional initiator [58]. Subsequent hydrolysis of the PMeOx blocks with HC1 in a methanol/ water mixture resulted in the formation of the corresponding polyethylen-imine blocks (Scheme 20). Samples with relatively low molecular weight distributions were obtained. 

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

A new approach to the synthesis of 2,4,5-trisubstituted and 2,5-disubstituted oxazoles, 97 and 98, used l-(methylthio)acetone 95 with nitriles in the presence of trifluoromethanesulfonic anhydride. The proposed mechanism involves an unstable 1-(methylthio)-2-oxopropyl triflate 96 which was detected using NMR spectroscopy <06JOC3026>. 

Activated amides have been generated by using trifluoromethanesulfonic anhydride in the presence of pyridine and been thionated with 20 wt% aqueous solution of ammonium sulfide to afford the desired secondary or tertiary thioamides in high yields (Scheme 13).34... 

Direct oxidation of bis-sulfides by trifluoromethanesulfonic anhydride was suggested only recently.57 For example, treatment of 10 with triflic anhydride affords the corresponding dication salt 34 in high yield via intermediate formation of a sulfonyl sulfonium salt 33.58 A number of other cyclic and acyclic bis-sulfides 35 undergo facile oxidation to dications under these conditions (Scheme ll).57... 

Intermediate allenyl cation 26 has been implied in the reaction of oct-3-yn-2-one (27) with trifluoromethanesulfonic anhydride, which forms vinyl triflates (equation 7)26. 

Aldehyde 26 was treated with hydroxylamine hydrochloride in refluxing methanol to give a mixture of (E)- and (Z)-pyrrolotriazine 40 in 59% and 21% yield, respectively. Dehydration of aldoxime 40 with trifluoromethanesulfonic anhydride and triethylamine in dichloromethane afforded triazine 41. Conversion of the nitrile 41 to the deprotected amide 42 was accomplished in 96% yield on treatment of 41 with basic hydrogen peroxide in ethanol <2001CAR77>. 

The reaction was performed in flame-dried modified Schlenk (Kjeldahl shape) flask fitted with a glass stopper or rubber septum under a positive pressure of argon. Trifluoromethanesulfonic anhydride (1.4 equiv) was added to a solution of giycosyl donor (0.191 mmol, 1 equiv) and diphenyl sulfoxide (2.8 equiv) in a mixture of toluene and dichloromethane (8 ml, 3 1 vol/vol) at — 78 °C. The reaction mixture was stirred at this temperature for 5 min and then at —40 °C for 1 h. At this time, 2-chloropyridine (5.0 equiv) and the giycosyl acceptor (3.0 equiv) were added sequentially at —40 °C. The solution was stirred at this temperature for 1 h, then at 0 °C for 30 min and finally at 23 °C for lh before the addition of excess triethylamine (10 equiv). The reaction was diluted with dichloromethane (100 ml) and was washed sequentially with saturated aqueous sodium bicarbonate solution (2 x 100 ml) and saturated aqueous sodium chloride (100 ml). The organic layer was dried (sodium sulfate) and concentrated. The residue was purified by silica gel flash column chromatography. 

To a solution of thioglycoside (1.0 equiv), Ph2SO (2.8 equiv) and TTBP (3.0 equiv) in dichloromethane (4.0 ml mmol-1) was added trifluoromethanesulfonic anhydride (1.4 equiv) at —60 °C under an argon atmosphere. The reaction mixture was... 

To a solution of thioglycoside (1.0 equiv), 1-benzenesulfinyl piperidine (1.0 equiv), TTBP (2.0 equiv), and freshly activated 3 A powdered molecular sieves in dichloromethane (25.0 ml mmol-1) was added trifluoromethanesulfonic anhydride (1.1 equiv) at —60 °C under an argon atmosphere. The reaction mixture was stirred for 5 min, after that a solution of the glycosyl acceptor (1.5 equiv) in dichloromethane (4.0 ml mmol-1) was added. The reaction mixture was stirred at — 60 °C for 2 min, after that it was slowly warmed to room temperature and quenched by the addition of saturated aqueous NaHC03. The organic layer was washed with brine, dried (MgS04), filtered and the filtrate was concentrated to dryness. Purification of the crude product by column chromatography over silica gel afforded the product. 

The most common activator for the glycosyl sulfoxides is trifluoromethanesulfonic anhydride (triflic anhydride), which, in the absence of nucleophiles, rapidly and cleanly converts most sulfoxides into the corresponding glycosyl triflates in a matter of minutes at —78 °C in dichloromethane solution [86,280,315,316]. In the more extensively studied mannopyranose series, only the a-mannosyl triflate is observed by low-temperature NMR spectroscopy (Scheme 4.35) [280]. In the glucopyranose series, mixtures of a- and (1-triflates are observed, in which the a-anomer nevertheless predominates (Scheme 4.36) [280],... 

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... 

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). 

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. ... 

Beccalli et al. reported a new synthesis of staurosporinone (293) from 3-cyano-3-(lH-indol-3-yl)-2-oxo propionic acid ethyl ester (1464) (790). The reaction of 1464 with ethyl chlorocarbonate and triethylamine afforded the compound 1465, which, on treatment with dimethylamine, led to the corresponding hydroxy derivative 1466. The triflate 1467 was prepared from 1466 by reaction with trifluoromethanesulfonic anhydride (Tf20) in the presence of ethyldiisopropylamine. The palladium(O)-catalyzed cross-coupling of the triflate 1467 with the 3-(tributylstannyl)indole 1468 afforded the vinylindole 1469 in 89% yield. Deprotection of both nitrogen atoms with sodium ethoxide in ethanol to 1470, followed by photocyclization in the presence of iodine as the oxidizing agent provided the indolocarbazole 1471. Finally, reductive cyclization of 1471 with sodium borohydride-cobaltous chloride led to staurosporinone (293) in 40% yield (790) (Scheme 5.248). 

Reaction with trifluoromethanesulfonic anhydride in benzene yields cop-per(I) trifluoromethanesulfonate, [Cu(03SCF3)]2 CeHs, a white crystalline, air-sensitive complex (Cotton, F. A., G. Wilkinson, C. A. Murillo and M. Bochmann. 1999. Advanced Inorganic Chemistry, 6th ed. pp. 857-858. New York Wiley Interscience) Olefins can displace benzene in the above compound readily, forming a variety of olefin complexes. 

A new route to 4-substituted pyrimidines involves the condensation of nitriles with iV-vinyl amides which are activated by trifluoromethanesulfonic anhydride and 2-chloropyridine <2006JA14254>. The method is illustrated by the synthesis of 4-cyclohexyl-2,5-diphenylpyrimidine 627 from A-styrylbenzamide 625 and cyclohexanecarboni-trile 626 in 89% yield <2006JA14254>. 

The synthesis of quinazoline derivatives by the addition of N(3)-C(4) fragment units has not previously been a major synthetic route, but 2,4-dialkyl, alkyl/aryl, and diaryl quinazolines 865 are now readily available by a new procedure that involves activation of A -arylamides 864 with trifluoromethanesulfonic anhydride and 2-chloropyridine, and subsequent addition of nitriles <2006JA14254>. Either normal or microwave heating can be used to perform the final ring-closure step. 

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