Sodium phenyl tellurolate

The easily available 1-bromo-l-seleno alkene, by treatment with sodium phenyl tellurolate under bis(bipyridine)nickel (11) bromide catalysis, furnishes the corresponding telluro(seleno)ketene acetal. " ... 

Sodium phenyl tellurolate is a milder reducing agent than phenyltellurol. The reduction of nitroarenes is therefore limited at the intermediate azoxy or azo compound stage, depending on the reaction temperature. The reagent is prepared in situ by treatment of diphenyl ditelluride with NaBH4 in ethanol in the presence of sodium hydroxide. Since the... 

Typical procedure Phenylcinnamyl telluride (prepared from sodium phenyl tellurolate, 1 mmol, and cinnamyl bromide, 1 mmol in EtOH, 10 mL) was treated with Phl=NTS (1.5 mmol) and the mixture was stirred at 25°C for 20 h. After removal of the solvent, the product was purified by column chromatography on Si02 (eluent hexane/AcOEt). 

Olefins and allylic alcohols from alkyl or cycloalkyl bromides and from epoxides (general procedures The i-alkyl or cycloalkyl bromide is treated with sodium phenyl tellurolate (1 equiv from diphenyl ditelluride and NaBH, see Section 3.1.3.2). The crude telluride is purified by SiOj chromatography (elution with hexane) and converted into the corresponding dibromide by addition of bromine (1 equiv) in CCI4, at 0°C. Epoxides are converted into j8-hydroxylalkyl and )3-hydroxycycloalkyl phenyl tellurium dibromide by a similar procedure, except that the intermediate tellurides are chromatographed on SiOj using hexane/EtOAc (5 1) as the eluent. 

Treatment of alkali metal alkyl or aryltellurolates (Section 5) with alkyl halides, aryl halides, alkenes, or alkynes have been used to prepare unsymmetrical tellurides, as exemplified by the reaction of sodium phenyl tellurolate or paramethylphenyl tellurolate with PhC=CHCOPh. ... 

Aldehydes and ketones are reduced to the corresponding alcohols by hydrogen telluride89 or phenyl tellurol.90 In addition, aromatic aldehydes can be reduced to the respective alcohols by sodium telluride in A-methyl-2-pyrroli-dinone (NMP)91 (Scheme 17). 

Under appropriate experimental conditions, hydrogen telluride, phenyl tellurol, and sodium hydrogen telluride perform the selective reduction of double bonds of a,/3-unsaturated carbonyl systems.89 90 This reaction with a,j3-unsaturated ketones complements the cerium trichloride/sodium borohydride method, which reduces the carbonyl group, keeping the carbon-carbon double bond intact92 (Scheme 18). 

The [3+2] cycloaddition reaction of sodium phenyl ethynyl tellurolate with di(methoxy-carbonyl)acetylene affords a trisubstituted tellurophene 24 in low yield (1%) (Equation 13) <1981ZOR2064>. 

Dibenzylidene-l, 3-ditelluretane was prepared by reacting tellurium with sodium phenylacetylide and acidifying the resulting mixture, which contains sodium phenylethyne-tellurolate, with hydrogen chloride in diethyl ether The structure of the compound was confirmed by single crystal X-ray analysis . The earlier reported formulation of this compound as 2-benzylidene-4-phenyl-l,3-ditelluracyclopent-4-ene is incorrect. ... 

The extreme sensitivity of tellurols to oxygen make the isolation of these tellurium compounds difficult. Therefore, tellurols are almost always used in situ. In the literature, tellurols are sometimes claimed to be the product of the reduction of diaryl ditelluriums in ethanol as the reaction medium. Tellurols are probably present under these conditions in equilibrium with the tellurolates. Whether the tellurols or the tellurolates are the reactive species, for instance, in addition reactions to carbon-carbon multiple bonds, cannot be decided without additional studies. Benzenetellurol, formed in situ by methanolysis of phenyl trimethylsilyl tellurium, was much less reactive towards acetylenes than the tellurium compound obtained by reduction of diphenyl ditellurium with sodium borohydride in ethanol5. 

Sodium benzenetellurolate is arylated in liquid ammonia via photoinduced reactions with aryl halides3,4. Aryl iodides reacted with sodium benzenetellurolate in the presence of copper(I) iodide in hexamethylphosphoric triamide (but not in DMF or DMSO) to produce aryl phenyl tellurium compounds5- However, lithium benzenetellurate reacted with 1,2-bromoiodobenzene and lithium methane tellurolate with 1,2-dibromobenzene in tetrahydrofuran at 20° to yield l,2-bis[organotelluro]benzenes6. 

Protonation of sodium phenylethynetellurolate by hydrogen chloride in diethyl ether led to 1,3-ditelluretane derivatives2 4 via cyclodimerization of the tellurol. 3,5-Dibenzylidene-1,2,4-tritellurolane was also isolated3. Protonation of sodium phenylethynetellurolate with trifluoroacetic acid affords 2-benzylidene-4-phenyl-l,3-ditellurole5. 

Sodium benzenetellurolate was also obtained by disproportionation of diphenyl ditellurium in strongly basic solution (tetrahydrofuran/50% aqueous sodium hydroxide). The reaction of the tellurolate with phenylselenobromomethane in the presence of dialkyldi-methylammonium chlorides as phase transfer agents yielded phenyl phenylselenomethyl tellurium. ... 

Benzoyl-l-phenyl-l-ethenyI 4-Methoxyphenyl TeUurium A 100-/w/, two-necked flask, fitted with a dropping funnel, a nitrogen inlet tube, and a magnetic stirrer, is charged with a solution of 4.7 g (10 mmol) of bis[4-methoxyphenyl] di tellurium in 10 m/ of absolute ethanol. The apparatus is flushed with nitrogen and 0.84 g (10 mmol) of sodium borohydride are added in small portions to the stirred solution kept at 20°. When the solution has become light yellow, a solution of 3.1 g (15 mmol) of phenyl(benzoyl)ethyne in 10 m/ of ethanol is added over 30 min to the stirred tellurolate solution. The yellow precipitate is filtered off yield 4.9 g (71%) m.p. 151° (from ethanol). 

Methoxyphenyl Phenyl Tellurium (Grignard Method) Phenyl magnesium bromide is prepared from 0.84 g (35 mmol) of magnesium and 5.5 g (35 mmol) of bromobenzene in 15 m/ of absolute diethyl ether under nitrogen and the resultant solution is cooled in an ice/watcr bath. 4.7 g (10 mmol) of bis [4-methoxyphenyl] ditellurium dissolved in 100 ml of absolute diethyl ether are added dropwise to the Grignard solution. Then 250 ml of petroleum ether (b.p. 30- 50°) are added to precipitate the tellurolate and the mixture is allowed to stand for 2 h. The precipitate is filtered off, the filtrate is mixed with aqueous ammonium chloride solution, the organic phase is separated, dried with sodium sulfate, and the solvent is evaporated. Methanol is added to the oily residue to crystallize the product yield 3.1 g (100%) m.p. 61° (from methanol). 

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