Ethyl trifluoroacetic anhydride

AijAT-dicyclohexylcarhodiimide (DCC) also leads to essentially quantitative conversion of amic acids to isoimides, rather than imides (30,31). Combinations of trifluoroacetic anhydride—triethjlarnine and ethyl chi oroform a te—triethyl amine also result in high yields of isoimides (30). A kinetic study on model compounds has revealed that isoimides and imides are formed via a mixed anhydride intermediate (12) that is formed by the acylation of the carboxylic group of amic acid (8). 

CjjHjoOioSi 115437-18-8) see Paclitaxel [(triethylsilyl)oxy]acetic acid ethyl ester (C oH220jSi) see Paclitaxel c -3-(triethylsilyloxy)-4-phenyl-2-azetidinone (Ci3H23N02Si) see Paclitaxel trifluoroacetic anhydride... 

Treatment of N-benzoyl-L-alanine with oxalyl chloride, followed by methanolic triethylamine, yields methyl 4-methyl-2-phenyloxazole-5-carboxylate 32 <95CC2335>. a-Keto imidoyl chlorides, obtained from acyl chlorides and ethyl isocyanoacetate, cyclise to 5-ethoxyoxazoles by the action of triethylamine (e.g.. Scheme 8) <96SC1149>. The azetidinone 33 is converted into the oxazole 34 when heated with sodium azide and titanium chloride in acetonitrile <95JHC1409>. Another unusual reaction is the cyclisation of compound 35 to the oxazole 36 on sequential treatment with trifluoroacetic anhydride and methanol <95JFC(75)221>. 

Utilizing Wenkert s cyclization process, a number of new approaches have been elaborated for the synthesis of simple indolo[2,3-a]quinolizine derivatives. For example, treatment of JV-[2-(indol-3-yl)ethyl]piperidine (V-oxide (134) with trifluoroacetic anhydride gave piperideinium intermediate 135 in a Polonovski-type reaction, which could be cyclized in acidic medium to ( )-l (101). 

Triethylamine, 46, 18 dehydrobromination of oi-bromo-y-butyrolactone with, 45, 23 Triethyl phosphonoacetate, reaction of sodium derivative with cyclohexanone to yield ethyl cyclo-hexylideneacetate, 46, 45 Trifluoroacetic anhydride, 45, 98 Teiphenylalctminum, 46,107... 

Method B A solution of 0.5 mmol of (2/ /.S,3/t/5 )-2,3-dialkyl-l,4-diarylbutane and 0.125 mL (1.0 mmol) of boron trifluoridc-dicthyl ether complex in 2 mL of CH2C12 is added to a stirred suspension of 0.12 g (0.26 mmol) of thallium(III) oxide in 10 mL of CH2C12 containing 0.4 mL of trifluoroacetic acid and 0.2 mL of trifluoroacetic anhydride at the stated temperature under argon. The mixture is stirred until the end of the reaction and then diluted with ethyl acetate and worked up as in method A. 

The separation of alditols as their trifluoroacetates has been reported by Shapira227 and by Japanese authors.213-228 The latter compared the reaction of trifluoroacetic anhydride in acetonitrile, tetra-hydrofuran, or ethyl acetate.213 They found that ethyl acetate is the most satisfactory, as acetonitrile causes tailing, and tetrahydrofiiran contains an impurity, not removed by distillation, which overlaps with fueitol per(trifluoroacetate). They found that, in ethyl acetate, mannitol reacts completely in 20 minutes, in contrast to the results of Shapira, who reported that hexitols require two hours at 35° when treated with trifluoroacetic anhydride and a trace of pyridine. The Japanese workers stated that the best separations were obtained on a column of 2% XF-1105, and that other columns, such as DC-1107, SE-30, or SE-52, caused tailing and broad peaks. 

Toluene, Sulfuric acid. Nitric acid Nitric acid. Sulfuric acid. Toluene Toluene, Sulfuric acid. Nitric acid. Methylene chloride Toluene, Sulfuric acid. Potassium nitrate. Methylene chloride Toluene, Sulfuric acid. Sodium nitrate. Methylene chloride Toluene, Sulfuric acid. Nitric acid. Premium unleaded gasoline Trifluoroacetic anhydride, Nitromethane, Ammonium nitrate, NIHT HCL, Ethyl acetate... 

TNTC Trifluoroacetic anhydride, Nitromethane, Ammonium nitrate, NIHT HCL, Ethyl acetate Secondary high explosive ... 

Alternatively, when 21 was treated with benzaldehyde diethyl acetal-hydrochloric acid, ethyl 3,5 4,6-di-0-benzylidene-L-gulonate (76) was formed in >90% yield. Diacetal 76 was efficiently oxidized to 77 (>90% yield) with dimethyl sulfoxide-trifluoroacetic anhydride, or by way of the nitrate of 76 and triethylamine. Hydrolysis of 77 then afforded ethyl L-xy(o-2-hexulosonate in 86% yield.383... 

The reaction of methyl 10, l l -dihydropyrrolo[ l, Z-b [ l, 2,5]bcnzothiadiazcpinc-l l -acetate 5,5-dioxide 73 or the corresponding ethyl ester 74 with potassium hydroxide in EtOH at 25 °C gave the acid 75 (Scheme 14), which upon treatment with trifluoroacetic anhydride in tetrahydrofuran (THF) underwent intramolecular cyclization to afford 76. The 1,2,5-thiadiazepines 73 and 74 were then heated with an excess of concentrated ammonium hydroxide to give the carboxamide 77. The acid 75 upon reaction with 4-chlorophenol, 4-chlorobenzyl alcohol, or 4-chloroaniline in the presence of iV-(3-dimethylaminopropyl)-iV -ethylcarbodiimide hydrochloride (EDCI) and 4-dimethylaminopyridine (DMAP) afforded the respective esters and amide 78-80 <1996FES425>. 

Finally, Winchester, Zappone and Skinner have reported the synthesis of 7,8-dihydro-8-oxa-9-oxopteroic acid (190) as part of a programme to evaluate members of this class of heterocyclic compounds as DHFR inhibitors [112]. In their approach (Scheme 3.36 ), the key intermediate acid (187) was prepared from 2,5-diamino-4,6-dihydroxypyrimidine and ethyl bromopyruvate followed by saponification [113]. Owing to the extreme insolubility of (187) in most solvents, it was converted to the disodium salt (188) and treated with excess trifluoroacetic anhydride to yield the mixed anhydride (189) [114]. Coupling with p-aminobenzoic acid and careful base hydrolysis gave (190), albeit in low... 

A suspension of 300 mg of adriamycin-14-valerate hydrochloride in 20 ml of ethyl acetate was treated with 0.45 ml of trifluoroacetic anhydride in small portions over a few minutes until all solids had dissolved. The solution was mixed immediately with equal portions of water and chloroform (total volume 100 ml). The chloroform layer was separated and washed once with water and twice with pH 7 aqueous buffer. The chloroform solution was dried over sodium sulfate and then was evaporated to dryness under reduced pressure. The residue was dissolved in 25 ml of methanol, and the resulting solution was heated at reflux for 5 minutes, then cooled and evaporated to dryness. The residue was redissolved in 4 ml of chloroform, and the crude product was precipitated by the addition of 20 ml of petroleum ether (b.p. 38°-49°C). The crude material was purified by chromatography on a silicic acid column. 

Lubkowitz [76] used ethyl trifluoroacetate for the preparation of TFA derivatives of 1,2-diaminocyclohexane in order to avoid the unpleasant properties of anhydride, such as its high reactivity, and the formation of a corrosive by-product. A three-fold excess of the reagent in anhydrous medium in the presence of ammonia leads to a yield of up to 99%. He resolved cis- and trans-isomers of 1,2-diaminocyclohexane on Versamide 900 stationary phase. 

The layer of K2C03 separated quantitatively, 0.2 ml of 2% periodate solution was added and the substrate was oxidized at 50°C for 30 min. The reaction was stopped by the addition of 0.2 ml of 10% sodium metabisulphite, the reaction mixture was cooled with water and vanillin was reduced to vanillyl alcohol by reaction with 100 ml of potassium boro-hydride at room temperature for 10 min. The pH was then adjusted to 7.0 with 5 N acetic acid and 0.6 ml of phosphate buffer (pH 7.2) was added. After mixing, the mixture was extracted with two 10-ml portions of ethyl acetate and the extracts were combined and evaporated to dryness at decreased pressure. In order to remove borate, methanol was added and the mixture again evaporated to dryness. The residue was transferred into a small vial with 2 ml of ethyl acetate and was treated with 0.5 ml of trifluoroacetic-anhydride at room temperature for 1 h. The contents of the vial were evaporated to dryness in an evacuated desiccator, the residue dissolved in 1 ml of ethyl acetate and 1 jul analysed on 3% OV-17 at 150°C. 

Allyl-7-amino-4-oxo-4H-chromene-2-carboxylic acid ethyl ester (32 mmol) dissolved in 400 ml of CH2C12 was treated first with A.IV-diisopropylethylamine (50 mmol), then trifluoroacetic anhydride (50 mmol) while cooling the mixture in an ice bath. The mixture was stirred 1 hour at ambient temperature, then washed with 200 ml apiece 2M HC1, saturated NaHC03 solution, and brine, dried with Na2S04, and filtered. The material was concentrated and 12.2 g product isolated as a pale yellow solid, mp = 136-137°C. 

Summary TNTC is prepared by treating NIHT.HC1 with nitromethane and ammonium nitrate in the presence of trifluoroacetic anhydride. After the reaction, the TNTC is contaminated with a by-product and hence needs to be purified. To do this, the contaminated TNTC is treated with ethyl acetate, and reciystallized. Commercial Industrial note For related, or similar information, see Application No. 471,906, January 29, 1990, by Gencorp Aerojet, to Der-Shing Hunag, Folsom, CA. Part or parts of this laboratory process may be protected by international, and/or commercial/industrial processes. Before using this process to legally manufacture the mentioned explosive, with intent to sell, consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

Selective trifluoroacetylation of primary amines in the presence of secondary amines can be accomplished by reaction with a stoichiometric amount of ethyl trifluoroacetate (bp 60-62 °C) in THF, acetonitrile or dioxane at 0 °C. The product is simply isolated by evaporation of the solvent and liberated ethanol,45-47 Perhaps the most common method entails acylation of the amine with trifluoro-acetic anhydride in the presence of a suitable base such as trie thy lamine or pyridine in dichloromethane [Scheme 8.26],40 New reagents for the N-trifluoro-acetylation of amines include Af-ftrifluoroacetyOsuccinimide,48 a solid and storable reagent, W-(trifluoroacetoxy)succinimide,49 which must be stored in a frozen benzene matrix, and l-(trifluoroacetyl)-l,2,3-benzotriazole.50 The latter reagent is a stable, crystalline reagent (mp 89-91 °C) prepared in quantitative... 

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