Benzenetellurinyl acetate

Mixed anhydrides such as benzenetellurinyl acetate (PhTe(O)OAc), benzenetellurinyl trifluoroacetate (PhTe(0)OCOCF3) and benzenetellurinyl trifluoromethanesulphonate (PhTe(0)0S02CF3), prepared by reacting benzenetellurinic anhydride with acetic anhydride, trifluoroacetic anhydride and trifluoromethane-sulphonic anhydride, respectively, have been recognized as valuable oxidizing reagents, in some cases superior to the parent benzenetellurinic anhydrides. ... 

When acetic acid was used to prepare benzenetellurinyl acetate, the crystallization of the product was difficult because of its hygroscopicity2. 

When the reactions of benzenetellurinyl acetate or trifluoroacetate to olefins were carried out with nitriles as solvents and boron trifluoride diethyl etherate as catalyst, 2-acylamino-1-alkyl phenyl telluroxides were obtained. Telluroxide elimination produces 4,5-dihydrooxazoles2. 

Hydroxyethyl)cyclopent-l-ene and benzenetellurinyl acetate formed an addition product containing a cyclie-ether functionality. This intermediate was reduced to the telluride, the telluride converted to the tellurium dibromide, and the dibromide heated in dimethylformamide with sodium bromide to give the brominated cyclic ether5. 

Benzenetellurinyl acetate and trifluoroacetate in chloroform add to terminal olefins and cycloalkenes at 20 or at the reflux temperature of the solvent in the presence of equimolar amounts of boron trifluoride etherate3. 

Benzenetellurinyl acetate (or trifluoioacetate) reacts with alkenes and carbamates under BF3 catalysis to give tt"ons, predominantly Maikovnikov, adducts, conveniently worked up via hydrazine reduction to give tellurides (Scheme 74) The trans nature of (63) was confirmed by indqiendent synthesis from PhTeNa and die rqipropriate aziridine. Alkenic carbamates undergo a much faster intramolecular telluro-lactamization (Sdieme 75) yields are 49-97% over IS varied examples. 

Benzenetellurinyl Acetate To a suspension of 0.457 g (1.0 mmol) of benzenetellurinic anhydride in 10 m/ chloroform are added 0.112 g (1.1 mmol) of acetic anhydride under an atmosphere of nitrogen. The mixture is refluxed for 30 min. When all the solid has disappeared, the solution is concentrated under reduced pressure. The residue is recrystallized from benzene/hexane. The colorless, hygroscopic crystals melted at 150-152° in a sealed tube yield 100%. 

Only a few examples of arenetellurinyl carboxylates, the mixed anhydrides of tellurinic acids and carboxylic acids, are known. These eompounds were prepared by refluxing mixtures of arenetellurinic acid anhydrides with acetic or trifluoroacetic acid or their anhydrides in chloroform . Acetonitrile and 1,2-dichloroethane were also used as solvents. Benzenetellurinyl trifluoroacetate is described as a very hygroscopic, intractable oil. The arenetellurinyl acetates are solids with melting points of approximately 150°. 

Better yields were obtained when benzenetellurinyl trifluoroacetate was used in place of the acetate. ... 

Alkenes are converted into 4,5-dihydrooxazoles by reaction with benzenetellurinyl trifluoro-acetate, boron trifluoride etherate, and acetonitrile (Equation (26)) <88TLI049>. 

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