Tellurium trifluoroacetate

The diaryl tellurium carboximides may exist in syn- and anti-forms if the N —C bond has double-bond character. The syrt-forms are stabilized by the proximity of opposite charges on the tellurium atom and the oxygen atom. Most of the diaryl tellurium trifluoroacet-imides only exist in the sy -form2. However, bis[4-methoxyphenyl] tellurium trifluoroacetimide was isolated in both forms. When the crude reaction product was dissolved in hot benzene and the resulting solution was cooled to and kept at 10°, cubic crystals of the antiform (m.p. 169°) precipitated. Addition of hexane to the hot filtrate precipitated the syn-form as an oil that crystallized on trituration with diethyl ether. The jy -form melted at 81°2. 

The 1,3-ditelluretane 88 is obtained as a minor product along with the 1,3-ditellurafulvene 89 by the reaction of phenylacetylide with tellurium followed by acidification with trifluoroacetic acid (Scheme 27) <2003TL2397>. In the reaction of trimethylsilylethynyl tellurolate, use of tifluoroacetic acid in /-butyl alcohol at — 20°C leads to the formation of the 1,3-ditelluretane 90, presumably via the telluraketene 91. Vilsmeier-Haack reaction on the crude ditelluretane 90 furnishes dialdehydes 27 and 92 in 10% yield. 1,3-Ditelluretanes 27 and 92 can be transformed into other derivatives, as shown in Scheme 28. An /. // mixture of 27 and 92 condenses smoothly with phosphorane to give diester product 93. The reaction with diesterdithiole phosphonate or dithiole phosphonate affords 1,3-ditelluretane derivative 94 or 95, respectively. 

Generation of the first tellurium-containing diheteropentalene has been reported <02OL1193>. Treatment of dibromide 131 with tellurium followed by silver trifluoroacetate gave intermediate 132 which upon treatment with base gave telluro[3,4-c]thiophene 133. Finally, benzo[b]tellurophene derivatives were synthesized and evaluated as selective dopamine D3 receptor antagonists <02JMC4594>. 

Treatment of bis[triethylsilyl]tellurium with trifluoroacetic acid at 20° gave triethylsilanetel-lurol in 73% yield1. 

Triethylsilanetellurol1 2.21 g (6.1 mmol) of bis[triethylsilyl] tellurium and 0.70 g (6.1 mmol) of trifluoroacetic acid are mixed under an inert atmosphere and kept at 20° for 1 h. The reaction mixture is then fractionated under reduced pressure in a stream of argon yield 0.70 g (73%) b.p. 90°/ 25 torr. 

Bis[fluoroalkoxy] Tellurium Oxides3 A solution of 7 mmol of acetic or trifluoroacetic anhydride was dropped to a stirred solution of 7 mmol of the tetrakis[fluoroalkoxy] tellurium compound in 25 ml of diethyl ether. When the exothermic reaction has subsided, the mixture is refluxed for 2 h and then kept at 20° for 12 h. The... 

Benzenetellurinyl trifluoroacetate and allyltrimethylsilanes reacted in 1,2-dichloroethane at 20° in the presence of boron trifluoride diethyl etherate to produce allyl phenyl telluroxides. The unstable telluroxides were not isolated but detected in solution by NMR spectroscopy. They were reduced to allyl phenyl tellurium derivatives with hydrazine hydrate. 

Diorgano tellurium oxides are reduced by hydrazine hydrate to diorgano tellurium compounds. The diorgano tellurium oxides are obtained as the primary products of the reactions of arenetellurinyl acetate or trifluoroacetates with olefins in chloroform, 1,2-dichloroethane, or acetonitrile as reaction media. When the olefin has a hydroxyl group in a f -, y-, or fi-position to the double bond, the addition of the tellurium compound to the double bond is followed by cyclization forming oxacycloalkane derivatives1. 

Reactions between benzenetellurinyl trifluoroacetate and cycloalkenes, terminal olefins, or internal olefins in acetonitrile with boron trifluoride-etherate as catalyst produced fi-acetamidoalkyl or -cycloalkyl phenyl tellurium oxides. These oxides were reduced with hydrazine hydrate in ethanol2. 

Benzenetellurinyl trifluoroacetate converts olefins in the presence of acetonitrile, propionit-rile, or benzonitrile, in a reaction catalyzed by boron trifluoride-diethyl etherate to 2-acylamino-1-ethyl phenyl tellurium oxides. The mixture was then heated at 75° for 3 h to effect elimination of the phenyltelluro group and cyclization to the dihydrooxazole5. 

Bis[trifluoromethyl] lellurium difluoride and excess trifluoroacetic anhydride reacted at 20° to liberate gaseous trifluoroacetyl fluoride and produce bis[trifluoromethyl tellurium bis[trifluoroacetate]. In acetonitrile as reaction medium the exchange of fluoride for trifluoroacctale did not go to completion2. 

Diorgano tellurium bis[trifluoroacetate] and l,2-bis[diphenylphosphano]ethane diselenide formed 1 1 complexes in refluxing dichloromethane2. 

Diphenyl tellurium bis[trifluoroacetate] reacted under the same conditions with tetrame-thylurea, sulfoxides, triphenylphosphane oxide and sulfide, triphenylarsane oxide, pyridine 1-oxides, tetramethylpiperidine, benzimidazole, morpholine, and 7V,Ar-diphenylthiourea to give 1 1 complexes as sharp-melting, colorless solids that are soluble in common organic solvents3. 

Diphenyl Tellurium Trifluoroacctate 2-Formylphenoxidel A solution of 2.28 g (20 mmol) trifluoroacetic acid in 50 ml diethyl etheris added to a solution of 5.23 g (10 mmol) of diphenyl tellurium bis[2-formylphenoxide] in 50 ml diethyl ether. The mixture is stirred for 2 hand then kept overnight in a deep-freezer. The crystals are collected by filtration and washed with petroleum ether (40-60°) m.p. 110°. 

Diphenyl Tellurium Trifluoracetate 8-Quinolinoxide2 A mixture of 1.14 g (10 mmol) trifluoroacetic acid, 5.45 g (10 mmol) diphenyl tellurium dioxinate, and 20 m/ dry benzene is refluxed for 4h. The mixture is concentrated and the concentrate mixed with an excess of diethyl ether to precipitate the product m.p. 170°. 

Bis[diphenyl tellurium acetate oxide was obtained in 64% yield when equimolar amounts of diphenyl tellurium oxide and diphenyl tellurium diacetate were refluxed in benzene2. The corresponding trifluoroacetate was prepared with methanol as the reaction medium3 at 20°. 

The trifluoroacetate was obtained as the hemihydrate upon slow evaporation of the methanol from a methanolic solution containing diphenyl tellurium oxide (2.5 mmol) and trilluoroacetic acid (5 inmol)3. 

When the reactions between benzcnetellurinyl trifluoroacetate and the olefins were carried out with acetonitrile as the solvent in the presence of some trifluoroacetic acid, 2-acetylaminoalkyl phenyl tellurium oxides were formed2. 

Benzenetellurinyl trifluoroacetate and 1-trimethylsily 1-2-propenes reacted at 20° in 1,2-dichloroethane in the presence of boron trifluoride etherate to give allyl phenyl tellurium oxides in almost quantiative yields. These compounds were not isolated but reduced to allyl phenyl telluriums with hydrazine hydrate or converted to allylamines2. 

Olefins react with benzenetellurinyl trifluoroacetate in acetonitrile in the presense of boron trifluoride etherate to give 2-acetaminoalkyl phenyl tellurium oxides that are converted, upon treatment with triethylamine in tetrahydrofuran at 30° for 4 h, to 4,5-dihydro-l,3-oxazoles4. These highly regio- and stereoselective reactions allow the one-pot, high-yield conversion of olefins to 1,3-oxazoles. Ethyl cyanide and phenyl cyanide can be used instead of acetonitrile. 

Allylsilanes react with benzenetellurinyl trifluoroacetate in 1,2-dichloroethane to give allyl phenyl tellurium oxides. Addition of amines to the reaction mixtures results in the formation of allylamines1. 

Heating bis[9-metacarboranyl] mercury with tellurium at 300° produced bi 9-metacar-boranyl] tellurium. The same compound was formed when 9-metacarboranyl thallium bis[trifluoroacetate] was made to react with tellurium in dimethylformamide in the presence of tetrabutyl ammonium iodide. ... 

Triethylsilanetellurol, prepared from bis[triethylsilyl] tellurium and trifluoroacetic acid (s.p. 18), and bis[triethylgermyl] mercury yielded, depending on reaction conditions, mercury bis[triethylsilanetellurolate or triethylgermylmercury triethylsilanetellurolate. ... 

Diorgano tellurium dichlorides and dibromides react with silver carboxylates " " or sodium carboxylates with formation of diorgano tellurium dicarboxylates. The same conversion was accomplished by shaking diaryl tellurium dichlorides with an Amberlite IR 45 resin in the carboxylate form or by treating bis[trifluoromethyl] tellurium dihalides with trifluoroacetic anhydride. ... 

The diorgano tellurium dicarboxylates are white, crystalline materials that are soluble in organic solvents and stable towards atmospheric agents. Diaryl tellurium diacetates can be boiled in water without decomposition. However, bis[trifluoromethyl] tellurium bis trifluoroacetate] was reported to be moisture-sensitive. Aqueous sodium hydroxide converts diaryl tellurium dicarboxylates to diaryl tellurium oxides or dihydroxides . Thermal gravimetric analysis of diaryl tellurium dicarboxylates indicated that these compounds lose carbon dioxide at 240-260° and form the tetraaryl tellurium derivatives. The tetraorgano tellurium compounds decompose slowly to the diaryl tellurium compounds and hydrocarbons. ... 

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