Benzenes trifluoromethanesulfonate

Sulfonic acids are such strong acids that in general they can be considered greater than 99% ionized. The piC value for sulfuric acid is —2.8 as compared to the piC values of —1.92, —1.68, and —2.8 for methanesulfonic acid, ethanesulfonic acid, and benzene sulfonic acid, respectively (3). Trifluoromethanesulfonic acid [1493-13-6] has a piC of less than —2.8, making it one of the strongest acids known (4,5). Trifluoromethanesulfonic acid is also one of the most robust sulfonic acids. Heating this material to 350°C causes no thermal breakdown (6). 

In order to achieve high yields, the reaction usually is conducted by application of high pressure. For laboratory use, the need for high-pressure equipment, together with the toxicity of carbon monoxide, makes that reaction less practicable. The scope of that reaction is limited to benzene, alkyl substituted and certain other electron-rich aromatic compounds. With mono-substituted benzenes, thepara-for-mylated product is formed preferentially. Super-acidic catalysts have been developed, for example generated from trifluoromethanesulfonic acid, hydrogen fluoride and boron trifluoride the application of elevated pressure is then not necessary. 

Bis[copper(I) trifluoromethanesulfonate] benzene complex Copper, [ Lt-(benzene)]bis(trifluoromethanesulfonato-0)di- (9) (37234-97-2)... 

The procedure described above provides a sufficient quantity of bis[copper(I) trifluoromethanesulfonate] benzene complex for several reactions at the scale used in Part C. If bis[copper(I) trifluoromethanesulfonate] benzene complex for a single reaction is desired, the same procedure can be followed at the appropriate scale without the use of the glove bag. In this case, the decolorized solution is not filtered but instead is cooled, and the product is allowed to crystallize in the reaction vessel. The supernatant benzene is decanted, and the crystals are washed in the flask with fresh benzene. The bis[copper(I) trifluoromethanesulfonate] benzene complex is then used without drying hj the same flask. 

Bromoanlsole Anisole, o-bromo- (8) Benzene, 1-bromo-2-methoxy- (9) (578-57-4) Methyl trifluoromethanesulfonate Methanesulfonic add, trifluoro-, methyl ester (8,9) (333-27-7)... 

Facile C-H bond activation by Pt(II) metal centers seems to require at least one labile ligand in the coordination sphere of platinum. One of the earliest intermolecular examples of this is the activation of C-D bonds in benzene-f/, by 0 an.S -(PAIe .) Pt(neopentyl)(OTf) at 133 °C, where trifluoromethanesulfonate (triflate, OTf) provides the labile group (Scheme 7, A) (26). 

Reaction of the 1,3,2-benzodiselenastannole (166) with selenium tetrachloride gives the triselenole (40) which is converted into the triselenolium hexafluorophosphate (20b) by reaction with nitrosyl hexafluorophosphate <94CC1593>. Benzo[l,2-rf][l,2,3]triselenolium chloride (20c) was obtained by reaction of 1,2-benzene-bis(selenenyl chloride) with selenium <92AG(E)779>. The structure of the trifluoromethanesulfonate (20a) has been established by x-ray crystallography (see Section 4.21.3.1). 

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. 

Alkenylpyrazines 112 react with benzene in trifluoromethanesulfonic acid giving anti-Markovnikov-type products 113 (Equation 18) <20050L2505>. 

Imines of acyclic and C10- to C15-membered carbocyclic ketones are prepared under the conditions described for cyclohexanone imines using trifluoromethanesulfonic acid or trifluoroacetic acid as additional catalyst. The reaction often takes several days in refluxing benzene or toluene9. 

Condensation of hydrazones 120 and 121 with methyl ethylphosphi-nate in the presence of trifluoromethanesulfonic acid in benzene for 35 h... 

Benzyne is an important reactive intermediate especially useful for the construction of polycyclic compounds via cycloaddition reactions with various dienes. Several benzyne precursors, including diphenyliodonium-2-carboxylate [ 1 ], have been previously used for the generation of benzyne by thermal decomposition. More recently, several new precursors that generate benzyne quantitatively under very mild conditions have been developed [105 -108]. An efficient benzyne precursor, iodonium triflate 109, can be readily prepared by the reaction of l,2-bis(trimethylsilyl)benzene 108 with [(diacetoxy)iodo]benzene in the presence of trifluoromethanesulfonic acid (Scheme 47) [105]. 

A review of solvent properties of, and organic reactivity in, ionic liquids demonstrates the relatively small number of quantitative studies of electrophilic aromatic substitution in these media.3 Studies mentioned in the review indicate conventional polar mechanisms. 1-Methylpyrrole reacts with acyl chlorides in the ionic liquid 1-butylpyridinium tetrafluoroborate to form the corresponding 2-acylpyrrole in the presence of a catalytic amount of ytterbium(III) trifluoromethanesulfonate.4 The ionic liquid-catalyst system is recyclable. Chloroindate(III) ionic liquids5 are catalytic media for the acylation, using acid chlorides and anhydrides, of naphthalene, benzene, and various substituted benzenes at 80-120 °C. Again the ionic liquid is recyclable. 

N-Tfa- and iV-Fmoc-a-amino ketones have been synthesized56 by reaction of some N -heterocycles or benzene with chiral AM Tfa- and Fmoc-a-aminoacyl)benzotriazoles [e.g. (49)] in the presence of aluminium trichloride. Full preservation of chirality was reported. Aromatic side-chains in some of the (a-amineacyl)benzotriazole compounds gave a competitive intramolecular cyclization, again with retention of chirality [e.g. (49) to (50)]. A full report57 on the intramolecular acylation of aromatics with Meldrum s acid derivatives catalysed by metal trifluoromethanesulfonates under mild reaction conditions has appeared [e.g. (51) to (52)]. The method tolerates many functional groups and was extended to the synthesis of 1-tetralones, 1-benzosuberones and donepezil (53). 

Oxetanes have also been used as alkylating agents in the Friedel-Crafts reaction for example, 2-isopropyloxetane was reacted with benzene in superacidic trifluoromethanesulfonic acid (TFSA) to give a mixture of alkylated aromatic products (Equation 9) <2003CAL1>. The main product of the reaction was the tetralin derivative 46 which could be isolated in up to 75% yield. Other notable side products are shown, resulting from monoalkylation or other skeletal rearrangements. 

Reaction of l,l,3,3-tetramethylindane-2-selenone with o-trimethylsilylphenyl trifluoromethanesulfonate in the presence of tetrabutylammonium fluoride affords benzoselenete 19 in 70% yield (Equation 5). Another sterically crowded selenone, di-ferT-butyl selenoketone, gives the corresponding benzoselenete 20 in 45% yield (Equation 6). When l,l,3,3-tetramethylindane-2-selenone is treated with benzenediazonium-2-carboxylate in refluxing benzene, compound 19 is obtained (27%) along with the rearranged product 36 in 7% yield (Equation 7) <2001JA7166>. 

Medium Highly acidic. Sources The ether lone pairs are best, with the aromatic ring a poor second. Sinks Trifluoromethanesulfonic acid (triflic acid) is a very strong acid with an estimated pATa of -15. Acidic Hs None. Leaving groups The ether oxygen, but only if protonated. Resonance forms Only benzene pi bond shift. 

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