Trifluoromethanesulfonic acid halides

Trifluoromethanesulfonic Acid. Trifluoromethanesulfonic acid (CF3SO3H, triflic acid), the first member in the perfluoroalkanesulfonic acid series, has been studied extensively, and excellent reviews describing its physical and chemical properties have been published.18,19 Besides its preparation by electrochemical fluorination of methanesulfonyl halides,20 triflic acid may also be prepared from... 

The CpW(CO)3 complexes 23 and 24 (obtained from CpW(CO)3Na and propargyl halides) undergo cyclization in the presence of trifluoromethanesulfonic acid (Scheme 9), followed by removal of the metal with trifluoroacetic acid to yield corresponding mono- and bicyclic lactones <1995JA2933>. 

Preparation. The reagents are prepared in 80 100% yields by the reaction of the silver salt of trifluoromethanesulfonic acid with acyl halides ... 

The most important method for the preparation of aryl ketones is known as Friedel-Crafts acylation. The reaction is of wide scope. Reagents other than acyl halides can be used," including carboxylic acids," anhydrides, and ketenes. Oxalyl chloride has been used to give diaryl 1,2-diketones." Carboxylic esters usually give alkylation as the predominant product (see 11-11)." A-Carbamoyl p-lactams reacted with naphthalene in the presence of trifluoromethanesulfonic acid to give the keto-amide." ... 

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. 

Trifluoromethanesulfonic acid, l,2-di-terT-butyl-l,l,2,2-tetra-phenyldisilane, toluene, diethyl ether, lithium halide. 

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. ... 

The boronic acid 2 is first converted to an activated species 8 containing a tetravalent boron center by reaction with a base. Halides or triflates (OTf = trifluoromethanesulfonate) are used as coupling partners R-X for the boronic acids. In many cases the rate-limiting step is the oxidative addition. With respect to the leaving group X, the rate decreases in the order ... 

Earle et al reported the first proof of the paradigm that the outcome of a chemical reaction can be radically altered by the choice of the ionic liquid as the solvent for the catalyst. The reactants were toluene and nitric acid in HCl for the following three ILs (1) [bmim][OTf, (2) [bmim][X], and (3) [bmim][OMs] where OTf is the trifluoromethanesulfonate anion, X = halide, and OMs = methanesulfonate salt. The reactions observed are described in Scheme 1. 

In relation to carbohydrate chemistry, the Koenigs-Knorr synthesis of glycosides involves the treatment of glycosyl halides with an alcohol or phenol in the presence of a heavy metal salt.267 Karrer268 discovered that reaction of silver salts of hydros acids could also be used and use of these reagents has been extended more recently. Numerous variations and improvements on the original method have now been reported, and silver oxide, silver carbonate or silver trifluoromethanesulfonate have since become the accepted standard reagents.267... 

Traditionally Lewis acid catalysed reactions often utilise metal halides, however in recent years, metal trifluoromethanesulfonates or triflates having the general formula Mn+(S02CF3)n have been reported as a new and interesting type of Lewis acid4. These... 

Conductivity measurements have revealed that DMF and carboxylic acid chlorides form salt-like adducts (22) in an equilibrium reaction (equation 12). Such adducts can be prepared either from DMF and acid halides (chlorides and bromides) or from chloromethyleneiminium salts and salts of carboxylic acids. Acyloxyiminium salts (23) can be prepared in the pure state by reacting acid amides with carboxylic acid chlorides in the presence of silver trifluoromethanesulfonate (equation 13). Salts of type (24 equation 14) are regarded as being intermediates in the synthesis of ketones from carboxylic acids and Grignard reagents in the presence of a-chloroenamines as well as in the preparation of acyl halides (F, Cl, Br, I) by action of a-haloenamines on carboxylic acids. ... 

The C-4 acids (183 and 184) have also been subjected to borane reduction conditions to afford alcohol 195 in 23-50% yield or 64% yield as the C-8 epimeric mixture (195 and 196, Scheme 29) [34, 49, 64]. The C-8 alcohol epimers 195 and 196 have been treated separately as a common intermediate for a number of C-4 derivatives including esters, ethers, and amines [34, 49, 64], Alcohols 195 and 196 was subjected to DCC, DMAP, and desired acid chloride or carboxylic acid in CH2CI2 affording ester analogs in 50-92% yield [64], Esters prepared include alkyl, aryl, and fluorenylmethyloxycarbonyl (Fmoc) protected amino acid derivatives (197 and 198) [64]. Ethers were prepared with various alkyl halides and Ag20 in CH3CN at 40 °C. Alkyl, allyl, and benzyl ethers were prepared in 45-80% yield (199 and 200) [34,64]. Alcohols 195 and 196 were then activated to the triflates and displaced by a variety of amines by treatment with trifluoromethanesulfonic anhydride and desired amine in 22% - quantitative yield over two steps (201 and 202)... 

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