Trifiuoromethanesulfonate

In the photolysis of difiuorodiazirine (218) a singlet carbene was also observed (65JA758). Reactions of the difiuorocarbene were especially studied with partners which are too reactive to be used in the presence of conventional carbene precursors, such as molecular chlorine and iodine, dinitrogen tetroxide, nitryl chloride, carboxylic acids and sulfonic acids. Thus chlorine, trifiuoroacetic acid and trifiuoromethanesulfonic acid reacted with difiuorodiazirine under the conditions of its photolysis to form compounds (237)-(239) (64JHC233). 

Diaryl sulfones can be formed by treatment of aromatic compounds with aryl sulfonyl chlorides and a Friedel-Crafts catalyst.167 This reaction is analogous to Friedel-Crafts acylation with carboxylic acid halides (1-14). In a better procedure, the aromatic compound is treated with an aryl sulfonic acid and P205 in polyphosphoric acid.168 Still another method uses an arylsulfonic trifiuoromethanesulfonic anhydride ArS020S02CF3 (generated in situ from ArS02Br and CF3S03Ag) without a catalyst.169... 

T. Ziegler, P. Kov4c, and C. P. J. Glaudemans, Transesterification during glycosylation promoted by silver trifiuoromethanesulfonate, Liebigs Ann. Chem. p. 613 (1990) and references cited therein. 

Figure 15 Synthesis of trisaccharide 16 TBDPS, f-butyldiphenylsilyl NIS, Al-iodosuc-cinimide AgOTf, silver trifiuoromethanesulfonate.

Quaternization is difficult benzofuroxan is unaffected by triethyl-oxonium fluoroborate, i i i With methyl trifiuoromethanesulfonate, an interesting rearrangement occurs, and 1-hydroxybenzimidazole-3-oxide (39, R = H) is formed, probably via the V-quaternized derivative... 

With further increasing leaving ability of Y, the reaction becomes dissociative and becomes a vinylic SnI (SnVI) reaction involving a vinyl cation as intermediate. SnV 1 reactions have been extensively studied, both with substrates giving stabilized vinyl cations and/or with substrates with a good nucleofuge such as triflate (trifiuoromethanesulfonate, TfO ) and are the subjects of several reviews." Their stereochemical consequences are discussed in Section 2. 

Due to the important role of nitrogen functional groups, the addition reactions of an electrophilic selenium reagent and a nitrogen nucleophile to a carbon-carbon double bond represent a synthetically relevant process with potential practical applications. Among the reactions of this type which have been described already, perhaps the most important contribution is represented by the Ritter-type amide synthesis described by Toshimitsu and Uemura [48a, 48b]. The addition of a phenylselenyl and of an acylamino group to a mono or a 1,2-disubstituted olefin was accomplished by treating the olefin with PhSeCl in acetonitrile and water in the presence of trifiuoromethanesulfonic acid. 

The stereospecific conversion of cyclohexene into the corresponding amido selenide 54 is illustrated in Scheme 8. These amidoselenenylation reactions are commonly employed for the preparation of allylic and saturated amides by oxidative or reductive deselenenylation. Propionitrile, butyronitrile, benzonitrile and ethyl cyanoacetate may be used in place of acetonitrile. Styrene gave poor results and other electron-rich olefins such as 1-methylcyclohexene or 2,3-di-methylbut-2-ene did not give the amidoselenenylation products. The reaction can also be effected starting from the hydroxy- or methoxyselenenylation products of alkenes, in the presence of water and trifiuoromethanesulfonic acid in this case the nitriles are used in stoichiometric amounts [48c]. This methodology was employed to prepare the amidoselenenylation products of styrene, 55, and of electron-rich olefins. It was necessary, however, to replace the phenyl-... 

The once popular deglycosylation with hydrofluoric acid requires longer response times in comparison to trifiuoromethanesulfonic acid and has smaller yields. In addition, special equip-... 

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, aUyl, and benzyl ethers were prepared in 45-80% yield (199 and 200) [34,64]. Alcohols 195 and 196 were then activated to the trifiates and displaced by a variety of amines by treatment with trifiuoromethanesulfonic anhydride and desired amine in 22% - quantitative yield over two steps (201 and 202)... 

ALDOL CONDENSATiON Di i-butylboryl trifiuoromethanesulfonate. Lithium bis(tri-methylsilyi)amide. Lithium l,l-bis(trimethylsiIyl)-3-methylbutoxide. Trichloro-ethanol. 

Similarly, poly(vinylbenzylchloride) was produced by free radical polymerization of 4-vinyl-benzylchloride and funchonalized with 3-amino-1, 2,4-triazole and IH-1,2,4-triazole [99], The polymers were doped with trifiuoromethanesulfonic acid at different molar ratios from 0.5 to 3 with respect to the aminotriazole and the triazole units. The samples are thermally stable up to approximately 200 °C. 

Subsequently, research on disulfonates intensified considerably. For example, in 2002 Mitsubishi Chenaical Corporation discovered fluorine-substituted chain disulfonates, such as 1,4-butanediol bis(trifiuoromethanesulfonate) (36) [69], as well as chain triol trisulfonates, such as 1,2,4-butanetriol trimethanesulfonate (37) [70]. 

Startg. alcohol in ether treated with p-methoxybenzyl trichloroacetimidate and a little (0.3 mol%) trifiuoromethanesulfonic acid at room temp, for 10 min - product. Y 77%. The method is mild, applicable to sterically hindered hydroxyl groups, and tolerates a wide range of both acid- (epoxide, bisspiroketal, acetonide, silyl) and base-sensitive (ester, mesyl, silyl) functions, even in 1,2- and 1,3-diol systems furthermore, there is no epimerization at the a-position of carbonyls or P-elimination of P-hydroxy compds. F.e.s. N. Nakajima et al.. Tetrahedron Letters 29,4139-42 (1988). 

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