Trifluoroacetic acid ethyl ester

The same method was also used for the synthesis of the anti-malarial compound mefloquine. Heterocyclization of 2-trifluoromethylaniline with trifluoroacetic acid ethyl ester provides 2,8-6w-(trifluoromethyl)-4-hydroxyquinoline. Bromination with phosphorous tribromide, followed a carbon monoxide introduction, affords 2,7-trifluoromethyl-4-carboxylic acid quinoline. Amide formation and pyridine reduction completes the synthesis providing mefloquine in high yields. ... 

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... 

Removal of the f-butyloxycarbonyl groups was obtained by treatment of 34a with a solution of trifluoroacetic acid in dichloromethane (1 1,0°C, 3 h). N-N-Hydroge-nolysis was achieved under H2 (75 psi, rt, 15 h) in the presence of a catalytic amount of Pt02 in ethanol to afford crystalline a-amino esters 36. Finally, the chiral auxiliary was cleaved and regenerated by nondestructive transesterification in the presence of Ti(OEt)4. The a-amino acid hydrochlorides (5)-37 were obtained by heating the crude amino acid ethyl esters in 6 N aqueous HC1 and after evaporation of the solution (Scheme 16). 

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. 

Chen et al. reported a more environmentally friendly version of the Pictet-Spengler reaction <06H1651>. In this report, a series of 2-phenylsulfonyl-l,2,3,4-tetrahydroisoquinoline-1-carboxylic acid ethyl ester derivatives 114 were synthesized in good yields through the cyclization of A-phenylsulfonyl-P-phenethylamines 115 with a-acyl sulfide 116 using phenyliodine(III) bis(trifluoroacetate) (PIFA) in ionic liquid ([bminjPFJ. The use of the ionic liquid allows for a simple purification and [bmin]PF can conveniently be recycled. 

Then, 1-(3-acetylthio-2-methylpropanoyl)-L-proline is produced. The 1-(3-acetylthio-3-methyl-propanoyl)-L-proline tert-butyl ester (7.8 g) is dissolved in a mixture of anisole (55 ml) and trifluoroacetic acid (110 ml). After one hour storage at room temperature the solvent Is removed in vacuo and the residue is precipitated several times from ether-hexane. The residue (6.8 g) is dissolved in acetonitrile (40 ml) and dicyclohexylamine (4.5 ml) is added. The crystalline salt is boiled with fresh acetonitrile (100 ml), chilled to room temperature and filtered, yield 3 g, MP 187°C to 188°C. This material is recrystallized from isopropanol [ttlo -67° (C 1.4, EtOH). The crystalline dicyclohexylamine salt is suspended in a mixture of 5% aqueous potassium bisulfate and ethyl acetate. The organic phase is washed with water and concentrated to dryness. The residue is crystallized from ethyl acetate-hexane to yield the 1-(3-acetylthio-2-D-methylpropanoyl-L-proline, MP83°Cto 85°C. 

Surprisingly, a-cyanoacrylic acid is reported to react spontaneously with triethylsilane in the absence of any additional acid to give a quantitative yield of the triethylsilyl ester of a-cyanopropionic acid.236 Ethyl a-cyanoacrylate requires the presence of trifluoroacetic acid to undergo reduction to ethyl 2-cyanopropionate.236 Many of these reductions are highly stereoselective. For example, treatment of... 

Ethyl trifluoroacetate Acetic acid, trifluoro-, ethyl ester (8,9) (383-63-1) m-Chloroperoxybenzoic acid Peroxybenzoic acid, m-chloro- (8) Benzocarboperoxoic acid, 3-chloro- (9) (937-14-4)... 

The initial 6,ll-dihydrodibenz[b,e]oxepin-ll-one (7.1.9) is synthesized from the ethyl ester of 2-phenoxymethyl benzoic acid (7.1.7), which is easily synthesized by reacting ethyl 2-bromomethylbenzoate with phenol in the presence of a base. The resulting ester (7.1.5) is hydrolyzed into 2-phenoxymethylbenzoic acid (7.1.8), which is cyclized to 6,11-dihydrodibenz[b,e]oxepin-ll-one (7.1.9) by trifluoroacetic acid anhydride. 

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>. 

Azotomycin is anticancer antibiotic produced by Streptomyces ambofaciens. Total sythesis of it from y-benzyl-N-tert-butyloxycarbonyl-L-glutamic acid (y-OBzi-N-Boc-L-Glu) has been accomplished in nine steps. The mixed carbonic anhydride method was chosen for peptide bond formation. Commerically available y-OBzi-N-Boc-L-Glu was esterified with ethereal diazomethane, deprotected with trifluoroacetic acid-methylene chloride (1 1), and converted to hydrochloride y-benzyl-L-glutamic acid a-methyl ester (y-OBzi-L-Glu-a-OMe HCI) by treatment with dry hydrogen chloride in ethyl ether, MP 129°-135°C (dec.) [a]D25= + 13.3° (CHCI3). 

A solution of 143.7 g of this t-butyl ester in 630 ml of trifluoroacetic acid was stirred at room temperature for one hour. The solvent was removed at reduced pressure and the residue was dissolved in ethyl ether and again evaporated. This operation was repeated. Then the ether solution was treated dropwise with a solution of hydrogen chloride gas in ethyl ether until precipitation ceased. The solid, collected by filtration, was a mixture of diastereoisomers of ethyl-a-[(l-carboxyethyl)amino]benzenebutanoate hydrochloride, melting point 153-165°C [a]D23 = +3.6° (1% MeOH). 

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