Tri fluoroacetates

If this electrostatic treatment of the substituent effect of poles is sound, the effect of a pole upon the Gibbs function of activation at a particular position should be inversely proportional to the effective dielectric constant, and the longer the methylene chain the more closely should the effective dielectric constant approach the dielectric constant of the medium. Surprisingly, competitive nitrations of phenpropyl trimethyl ammonium perchlorate and benzene in acetic anhydride and tri-fluoroacetic acid showed the relative rate not to decrease markedly with the dielectric constant of the solvent. It was suggested that the expected decrease in reactivity of the cation was obscured by the faster nitration of ion pairs. 

Benzamidomethyl-A -methylcysteine has been prepared as a crystalline derivative (H0CH2NHC0C6H 5, anhydr. CF3CO2H, 25°, 45 min, 88% yield as the tri-fluoroacetate salt) and cleaved (100% yield) by treatment with mercury(II) acetate (pH 4, 25°, 1 h) followed by hydrogen sulfide. Attempted preparation of S-acetamidomethyl-N-methylcysteine resulted in noncrystalline material, shown by TLC to be a mixture. ... 

Perfluoroalkanoyl chlorides and anhydrides are also acylating agents Tri-fluoroacetic anhydride acylates a number of pyrroles, thiophenes, and furans without a catalyst [37, 38, 39] AzuUne can be diacylated without a catalyst in 12 h [40] (equation 26). 

In the past 20 years, the application of fluorinated reagents in chemistry experienced tremendous growth Some well known denvatives of hydrofluoric acid and tri-fluoroacetic acid found new applications, and many new classes of synthetically useful fluorinated organic and inorganic compounds have been synthesized... 

Thus it can be seen that evidence for the A-l mechanism, even if one accepted that this followed from a linear rate coefficient-acidity function correlation, was scant. On the other hand, there have been a very large number of carefully documented studies in which general acid catalysis has been observed leading to the A-Se2 mechanism for the reaction, or it has been shown that the conclusions from an acidity function dependence are not rigorous. One such study has already been described above, and Satchell478 also found that in the detritiation of [4,6-3H2]-l,2,3-trimethoxybenzene by potassium bisulphate, dichloro- and tri-fluoroacetic acids, plots of log kl versus —H0 were linear with a slope of ca. 1.0... 

Both the submitters and the checkers used thallium(III) tri-fluoroacetate prepared from thallium(III) oxide and trifluoroacetic acid.3 Although this material may be purchased from Aldrich Chemical Company, Inc. and Eastman Organic Chemicals, the submitters recommend that the reagent be freshly prepared prior to use. 

Specifically, it has recently been found 149) that diarylthallium tri-fluoroacetates may be converted into aromatic iodides by refluxing a solution in benzene with an excess of molecular iodine. Yields are excellent (74-94%) and the overall conversion represents, in effect, a procedure for the conversion of aromatic chlorides or bromides into aromatic iodides via intermediate Grignard reagents. The overall stoichiometry for this conversion is represented in Eq. (10), and it would appear that the initial reaction is probably formation of 1 mole of aromatic iodide and 1 mole of arylthallium trifluoroacetate iodide [Eq. (8)] which subsequently spontaneously decomposes to give a second mole of aromatic iodide and thallium(I) trifluoroacetate [Eq. (9)]. Support for this interpretation comes from the... 

The combination of CsF with Si(OMe)4 58 is an efficient catalyst for Michael additions, e.g. of tetralone 130 to methacrylamide, followed hy cyclization of the addition product to the cyclic enamide 131 in 94% yield [67]. Likewise, addition of the lactone 132 to methyl cinnamate affords, after subsequent cyclization with tri-fluoroacetic acid, the lactam 133 in 58% yield [68] whereas < -valerolactam 134, with ethyl acrylate in the presence of Si(OEt)4 59/CsF, gives 135 in 98% yield [69]. Whereas 10mol% of CsF are often sufficient, equivalent amounts of Si(OEt)4 59 seem to be necessary for preparation of 135 [69] (Scheme 3.11). 

The first electrochemical H2 generation catalyzed by a hetero-nuclear Fe-Ni complex [Ni(L)Fe2(CO)g] (27) [L - = (CH3C6H3S2)2(CH2)3 ] (Fig. 9) with tri-fluoroacetic acid was reported by Schoder and coworkers in 2006 [211]. Based on their electrochemical behavior, spectroscopic data, and DFT calculations of 27, an EECC mechanism was mled out and therefore an ECCE or ECEC mechanism involving the formation of Fe°-H and Ni -H intermediates is likely. In this cycle, six catalytic turnovers were achieved. This value is comparable to those for... 

Anhydrous peroxytrifluoroacetic acid is not easy to handle, but the procedure has recently been revised.121 Namely, reaction of urea-hydrogen peroxide complex (UHP) with tri-fluoroacetic anhydride in acetonitrile at 0 °C gives solutions of peroxytrifluoroacetic acid, which oxidize aldoximes to nitroalkanes in good yields (Eqs. 2.58 and 2.59). Ketoximes fail to react under these conditions, the parent ketone being recovered. 

Secondary Alkyl Alcohols. Treatment of secondary alkyl alcohols with tri-fluoroacetic acid and organosilicon hydrides results only in the formation of the trifluoroacetate esters no reduction is reported to occur.1,2 Reduction of secondary alkyl alcohols does take place when very strong Lewis acids such as boron trifluoride126 129 or aluminum chloride136,146 are used. For example, treatment of a dichlo-romethane solution of 2-adamantanol and triethy lsilane (1.3 equivalents) with boron trifluoride gas at room temperature for 15 minutes gives upon workup a 98% yield of the hydrocarbon adamantane along with fluorotriethylsilane (Eq. 10).129... 

The most common reaction conditions for alkene reductions use excess tri-fluoroacetic acid and triethylsilane either neat202 204 or in an inert solvent such as nitrobenzene,134 2-nitropropane,205 carbon tetrachloride,206 chloroform,207 or dichloromethane.127,164 Reaction temperatures from —78° to well over 100° are reported. Ambient or ice-bath temperatures are most commonly used, but variations of these conditions abound. 

Namely, allyl alcohol is successively treated with diethylzinc, (R,R) dipropyl tartrate, and 4-methoxybenzohydroximinoyl chloride (163) to afford the enantiomeric isoxazoline alcohol 166, which under the Jones oxidation conditions affords the corresponding carboxylic acid derivative (167). Treatment of compound 167 with hydroxylamine-O-triflate followed by tri-fluoroacetic acid gives rise to the desired enantiomeric 165 in high excess enantiomeric yield. The synthesis of other isosteric analogues of 165 was reported in the same paper. None of the isosteric analogues exhibits LpxC inhibitory and antibacterial activities [103]. 

Ionic hydrogenations of C=C and C=0 bonds were reported prior to the development of ionic hydrogenations mediated or catalyzed by transition metals. Tri-fluoroacetic acid (CF3C02H) as the proton donor and triethylsilane (HSiEt3) as the hydride donor are most commonly used, though a variety of other acids and several other hydride donors have also been shown to be effective. A review [1] by Kursanov et al. of the applications of ionic hydrogenations in organic synthe-... 

The carbamates of tertiary acetylenic alcohols have also been made by reaction of these alcohols with sodium cyanate in tri-fluoroacetic acid.9 The yields by this procedure are significantly lower than those obtained by the present modification, which is essentially that described by Loev and Kormendy.5... 

The formation of iminium ions of 20-epipandoline occurred only under Polo-novski-Potier conditions. Thus on treatment of the TV-oxide of 165 with tri-fluoroacetic anhydride followed by an aqueous solution of KCN, the iminium ion 329 was obtained, readily isolated as the corresponding a-amino nitrile 331 (Scheme 17). The reaction was completely regioselective and no traces of the enamine 332 could be obtained. This made the synthesis of spiroketone 333... 

The reaction is believed to begin with the metalation of the substrate via aromatic electrophilic substitution (SEAr) followed by CO insertion and nucleophilic displacement by water or another protic nucleophile such as tri-fluoroacetic acid (TFFA) to give, respectively, the aromatic carboxylic acid or its mixed anhydride derivative, from which the acid is freed by hydrolysis (Scheme 24). 

CS2 and acetone. The increases of 1.3-2.0 Hz depending on the temperature were about half the size of the temperature effects. Both were attributed to self association of the ethyl formate. Dhingra et al. 28> reported that /13 of tri-fluoroacetic acid increases with decreasing concentration in CC14, dioxane, acetone, water and acetonitrile. The change was apparently in order of the di-... 

In a potassium acetate-acetic acid medium, 2-fluoro- and 4-fluoroanisole can be oxidized at platinum to afford 2-acetoxy- and 4-acetoxyanisole, respectively [19]. Using a platinum anode in a trifluoroacetic acid-potassium tri-fluoroacetate solution, Blum and Ny-berg [20] electrooxidized hexafluoroben-zene to tetrafluorobenzoquinone in 75% yield, and octafluoronaphthalene was converted into hexafluoronaphthoquinone in 60% yield. 

---