Esters trifluoroacetyl

Gas Chromatography of Bile Acids as Their Hexafluoroisopropyl Ester Trifluoroacetyl Derivatives J. Chromatogr. 120(1) 181-186 (1976) CA 85 1989w... 

Trifluoroacetamides are more stable toward nucleophiles than the corresponding esters and are easily formed from trifluoroacetic anhydride and the amine. The trifluoroacetyl group (Tfac) is slowly cleaved by aqueous or methanolic HQ, NH, or Ba(OH)2 solutions as well as by NaBHj in methanol (M.L. Wolfrom, 1967). 

Nonvolatile analytes must be chemically converted to a volatile derivative before analysis. For example, amino acids are not sufficiently volatile to analyze directly by gas chromatography. Reacting an amino acid with 1-butanol and acetyl chloride produces an esterfied amino acid. Subsequent treatment with trifluoroacetic acid gives the amino acid s volatile N-trifluoroacetyl- -butyl ester derivative. 

Diamide Chiral Separations. The first chiral stationary phase for gas chromatography was reported by GH-Av and co-workers in 1966 (113) and was based on A/-trifluoroacetyl (A/-TFA) L-isoleucine lauryl ester coated on an inert packing material. It was used to resolve the tritiuoroacetylated derivatives of amino acids. Related chiral selectors used by other workers included -dodecanoyl-L-valine-/-butylamide and... 

Trifluoroethanol was first prepared by the catalytic reduction of trifluoroacetic anhydride [407-25-0] (58). Other methods iaclude the catalytic hydrogeaatioa of trifluoroacetamide [354-38-1] (59), the lithium aluminum hydride reductioa of trifluoroacetyl chloride [354-32-5] (60) or of trifluoroacetic acid or its esters (61,62), and the acetolysis of 2-chloro-l,l,l-trifluoroethane [75-88-7] followed by hydrolysis (60). More recently, the hydrogenation of... 

The synthesis and the quantitative gas chromatographic analysis of stable, yet volatile, A/-trifluoroacetyl- -butyl esters of amino acids has been estabhshed (124). An extensive review of subsequent advances ia gas chromatographic iastmmentation has been provided (125). 

The resolution of optically active compounds by gas chromatography with chiral phases is a well-established procedure, and the separation of Al-perfluoto-acetylated ammo acid ester enantiomers m 1967 was the first successful application of enantioselective gas-liquid chromatography [39] Ammo acids have been resolved as their A -trifluoroacetyl esters on chiral diamide phases such as N-lauroyl-L-valineferf-butylamideorAl-docosanoyl-L-valme /ez-r-butylamide [40,41,... 

Trifluoroacetyl)benzotriazole, THF, rt, 85-100% yield. This reagent can be used to prepare trifluoroacetate esters. 

When aziridine-2-carboxylic ester 124 (Scheme 3.44) was treated with 1 equivalent of TFA, 125 was formed as a single diastereomer in 80% yield [57]. Use of 10 equivalents of TFA resulted in the formation of N-trifluoroacetyl product 126. This... 

Thus other trifluoroacetylation reagents have been investigated. iS -Ethyl trifluorothioacetate [Ethanethioic acid, trifluoro-, S-ethyl ester]6 has none of the above disadvantages. It does require, however, weakly basic conditions (pH 8-9) and an aqueous medium. Phenyl... 

Polymeric reagents, oxidation with, 99 Potassium cyanide, 20 L Proline, N bcnzyloxycarbonyl-3-hydroxy-[1,2-Pyrrohdinedicarboxyhc acid, 3-hydroxy, 1 (phenylmcthyl) ester], 89 L Proline, N trifluoroacetyl [2-Pyrrohdine-carboxylic acid, 1 (trifluoroacetyl), (5)-], 125... 

Kinetic studies also provide other evidence for the SnI mechanism. One technique used F NMR to follow the solvolysis of trifluoroacetyl esters. If this mechanism operates essentially as shown on page 393, the rate should be the same for a given substrate under a given set of conditions, regardless of the identity of the nucleophile or its concentration. In one experiment that demonstrates this, benzhy-dryl chloride (Ph2CHCl) was treated in SO2 with the nucleophiles fluoride ion, pyridine, and triethylamine at several concentrations of each nucleophile. In each case, the initial rate of the reaction was approximately the same when corrections were made for the salt effect. The same type of behavior has been shown in a number of other cases, even when the reagents are as different in their nucleophilicities (see p. 438) as H2O and OH . 

Af-(trifluoroacetyl)- [1480-30-4], 56,125 E-LEUCINE, N-[N -[(PHENYLMETH-0XYX ARB0NYL] -L-ASPARA-GINYL] -, METHYL ESTER [14317-83-0],56, 88... 

Trifluoroacetylbenzotriazole,[125a] which is easily prepared from benzotriazole and trifluoroacetic anhydride, is a very expedient trifluoroacetylating agent. Because of its stability the solid product can be stored in the covered bottle for several weeks without decomposition. By reaction with alcohols the trifluoroacetate esters were obtained in high yields ... 

N-Trifluoroacetylations of amino acid esters by a pyrazolide are described in reference [121]. 

Bis(fluoroformyl) peroxide, 0625 Bis-3-(2-furyl)acryloyl peroxide, 3640 Bis(trichloroacetyl) peroxide, 1361 Bis(trifluoroacetyl) peroxide, 1367 Diacetyl peroxide, 1537 Dibenzenesulfonyl peroxide, 3499 Dibenzoyl peroxide, 3639 Di-3-camphoroyl peroxide, 3807 Dicrotonoyl peroxide, 2986 Dicyclohexylcarbonyl peroxide, 3667 Didodecanoyl peroxide, 3857 Di-2-furoyl peroxide, 3245 Dihexanoyl peroxide, 3554 Diisobutyryl peroxide, 3032 Diisopropyl peroxydicarbonate, 3034 Dimethanesulfonyl peroxide, 0931 Di-2-methylbutyryl peroxide, 3354 Di-l-naphthoyl peroxide, 3831 3,6-Dioxo-l,2-dioxane, 1445 Dipropionyl peroxide, 2442 Dipropyl peroxydicarbonate, 3035 Di-4-toluenesulfonyl peroxide, 3656 Peroxodisulfuryl difluoride, 4328 Phthaloyl peroxide, 2900 Potassium benzenesulfonylperoxosulfate, 2257 Potassium O-O-benzoylmonoperoxosulfate, 2684 (9-TriIIuoroacctyl-.S -lluorofonny 1 thioperoxide, 1050 See PEROXIDES, PEROXYCARBONATE ESTERS... 

Usually alcohols accompany aldehydes in reductions with lithium aluminum hydride [1104] or sodium bis 2-methoxyethoxy)aluminum hydride [544], or in hydrogenolytic cleavage of trifluoroacetylated amines [7772]. Thus terr-butyl ester of. -(. -trifluoroacetylprolyl)leucine was cleaved on treatment with sodium borohydride in ethanol to rerr-butyl ester of A7-prolylleucine (92% yield) and trifluoroethanol [7772]. During catalytic hydrogenations over copper chromite, alcohols sometimes accompany amines that are the main products [7775]. 

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