Diphenyl ditellurides

Recently, Kondo and coworkers reported on the polymerization of St with diphenyl diselenides (37) as the photoiniferters (Eq. 39) [ 162]. In the photopolymerization of St in the presence of 37a and 37b, the polymer yield and the molecular weight of the polymers increased with reaction time. The chain-end structure of the resulting polymer 38 was characterized. Polymer 38 underwent the reductive elimination of terminal seleno groups by reaction with tri-n-butyltin hydride in the presence of AIBN (Eq. 40). It also afforded the poly(St) with double bonds at both chain ends when it was treated with hydrogen peroxide (Eq. 41). They also reported the polymerization of St with diphenyl ditelluride to afford well-controlled molecular weight and its distribution [163]. 

Diphenyl ditelluride adds to alkynes upon irradiation with a tungsten lamp in the absence of solvent to give 1,2-bis(phenyltelluro)alkenes (Equation (67)).191 The ( )-isomers are obtained as the major product through a radical chain mechanism. Functionalized internal alkynes such as dimethyl acetylenedicarboxylate and dihaloalkynes XCCX (X = C1 or Br) are able to participate in the reaction.192... 

Alkyl phenyl tellurides (general procedure) Li metal (1.4 g, 0.2 mol) in small pieces is added under N2 to a solution of diphenyl ditelluride (4.1 g, 10 mmol) in dry THF (100 mL). The mixture is stirred at room temperature for 6 h, unreacted lithium is removed using a spatula and the aUcyl halide (20 mmol) neat or in THF is added dropwise to the stirred yellowish-brown solution. The solution is stirred at room temperature for 30 min, and under reflux for an additional 30 min. The solvent is evaporated, and HjO (10 mL) and ether (25 mL) are added to the residue, mixing thoroughly. The ethereal phase is separated and evaporated. The residue is fractionally distilled under vacuum (yields 62-79%). 

Diisobutylaluminium benzeneteUurolate, generated in situ from diphenyl ditelluride and diisobutylaluminium (DIBAL), reacts with acetals, alkyl sulphonates and oxiranes, giving the expected tellurides in high yields. ... 

Diphenyl ditelluride (typical procedure) To a suspension of powdered Te (25.5 g, 0.2 mol) in anhydrous THF (300 mL), 2.0 M phenyllithium (100 mL, 0.2 mol) is added dropwise, with stirring and under argon. The resultant mixture is stirred at room temperature for 2 h and under reflux for 1 h. The reaction mixture, which should contain only a small amount of unreacted Te, is allowed to cool to 20°C, and is poured into 1 L of H2O. Oxygen (or air) is bubbled for 1 h through the mixture, which is then extracted with benzene (100 mL). The benzene solution is washed three times with H2O, dried (Na2S04) and evaporated. The residue is recrystallized from EtOH (77% m.p. 63.8-65.0°C). 

Diphenyl ditelluride (typical procedure) lodobenzene (130 mg, 0.64 mmol) is added dropwise to a stirred solution of Na2Te (1.3 mmol) in NMP (4 luL) and the mixture is heated at 120°C for 5 h. After cooling, the mixture is diluted with benzene (5 luL), and a stream of air is bubbled into the dark solution. Free Te which separates is removed by filtration and the filtrate is worked up as usual to give the crude ditelluride, which is purified by recrystallization from a mixture of hexane and EtOAc (3 1) to give the pure product (90 mg (66%)). 

Methoxycyclohexyl)phenyltellurium dibromide (typical procedure) To a solution of phenyltellurium tribromide (from diphenyl ditelluride (1.02 g, 2.5 mmol) and Br2 (1.20 g, 7.5 mmol) in MeOH (5 mL) is added cyclohexene (0.49 g, 6.0 mmol) and the mixture is heated under reflux for 1 h. By cooling the yellow solution at room temperature, the dibromide precipitates (1.45 g (61%) m.p. 169-171°C). 

Diphenyl ditelluride, on irradiation with visible UghL effects the v/c-phenyltelluration of acetylenes, giving the corresponding bis-phenyltelluroalkenes in good yields. ... 

The same ketene acetal, as well as telluro(thio)ketene acetals has been obtained with retention of configuration by subsequent treatment of ( )-l-bromo-l-seleno(or thio) alkenes with n-BuLi and diphenyl ditelluride, resulting from the preferential Br/Li exchange over chalcogeno exchange. ... 

Method B A mixture of diphenyl ditelluride (2.05 g, 5 mmol), NaBH4 (0.397 g, 10.5 mmol) and dry EtOH (20 mL) is heated with stirring under Ng atmosphere for 15 min, when most of the ditelluride had produced an almost colourless solution. The solution is then cooled to 20°C and TEA (0.81 g, 10.5 mmol) in EtOH (5 mL) is added, followed by a solution of acenaphthylene (0.305 g, 2 mmol) in EtOAc (20 mL). The mixture is refluxed for 4 h, then diluted with cold HgO (500 mL) and worked up in the usual manner, including SiOg chromatography, to give diphenyl ditelluride (1.93 g (94%)) and acenaphthene (0.300 g (98%)). 

The reagent is easily generated in situ by the previously described methods (methods A and B ), or by the reduction of diphenyl ditelluride with NaBH4 (method C). In the last... 

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... 

Phenyl tellurium pentafluoride, easily prepared from diphenyl ditelluride and xenon difluoride (Xep2), reacts smoothly with olefins affording the corresponding 1,2-difluorides. ... 

Indeed, aliphatic olefins treated with equivalent amounts of diphenyl ditelluride and f-BuOOH in methanol in the presence of sulphuric acid give methoxytellurenylated adducts. ... 

If the two described aminoteUurinylation procedures are performed at a higher temperature, tellurium-free products are obtained in high yields 2-oxazolidinones and 2-oxa-zolines, respectively. Diphenyl ditelluride is formed as by-product. These heterocycles constitute an important class of compounds with wide applications. 

Diphenyl ditelluride reacts withp-nitrobenzenesulphonyl peroxide (NBSP), generating the title compound. This efficient electrophilic reagent reacts in situ with 4-pentenoic acid, allowing the formation of the corresponding tellurobutyrolactone. ... 

Tellurolactonization of 4-pentenoic acid (typical procedure) f To a solution of diphenyl ditelluride (0.102 g, 0.5 mmol) in freshly distilled MeCN (20 mL) is added solid NBSP (0.170 g, 0.5 mmol), in small portions at 0°C, and the solution is stirred for 10 min. 4-Pentenoic acid (0.130 g, 1.1 mmol) is added, the solution is stirred for 2 h at 0°C, then... 

In the thermal procedure C the substrate is heated at 230-250°C under reduced pressure (in a Kugelrohr distillation apparatus) (method C ) ° or heated in DMF at 70-100°C in the presence of an additional alkali metal halide (method The tellurium moiety is isolated as diphenyl ditelluride, despite the formal formation of phenylteUurenyl halide. 

The by-product of the elimination, phenyltellurenic acid, is detected, at least partly, as diphenyl ditelluride, and is probably formed by disproportionation and oxidation reactions. 

Method a + c. The tellurium dibromide (1.0 mmol) in THF (20 mL) is treated with 0.5 N NaOH (10 mL) at room temperature with stirring, and the resnlting solntion is stirred for 1 h, the colour of the solution turning to orange. The mixtnre is dilnted with brine and extracted with ether. The extracts are dried (MgS04), evaporated nnder vacnnm and the residue purified from diphenyl ditelluride by Si02 chromatography (elntion with hexane). The pure olefin is isolated by distillation of the residne. 

Thiotelluration of 1-styrylcyclopropane In a Pyrex glass tube were placed 1-styrylcy-clopropane (0.2 mmol, 28.8 mg, 0.4 M), diphenyl disulphide (0.2 mmol, 43.7 mg, 0.4 M), diphenyl ditelluride (0.2 mmol, 81.9 mg, 0.4 M) and CDCI3 (0.5 mL). The tube was filled with Ar, and the mixture was irradiated at 40°C for 7 h through a filter (hv >400 nm) with a tungsten lamp (500 W). The solvent was evaporated in vacuo. Purification by a recycling preparative HPLC (CDCI3) yielded 77 mg (84%, E/Z= 14 86) of 2-phenyl-l-(phenylthio)-5-(phenyltelluro)-2-pentene as a pale yellow oil. 

The inhibitory effect of diphenyl ditelluride (compared to diphenyl diselenide) on [ H]glutamate, [ H]MK-801 and total [ H]GMP-PNP binding ex vivo and in vitro to synaptic membrane preparations of rat brain has been studied. This shows that diorganyldi-tellurides are more reactive than structurally related selenium compounds, because the dose of diphenyl diselenide used was about eight times higher than that of diphenyl ditelluride to cause similar effect. 

However, the reactivity in vitro towards biological systems is not always in agreement with this role, because [ H]glutamate binding was more sensitive to diphenyl ditelluride than diphenyl diselenide, and other bindings were similarly affected by both compounds. ... 

It was also demonstrated that acute exposure to diphenyl ditelluride did not change [ H]glutamate release and uptake by rat brain synaptosomes. In contrast, in vitro experiments indicate that 100 am of diphenyl ditelluride clearly inhibit [ H]glutamate uptake by brain synaptosomes and synaptic vesicles. These results also suggested that the inhibitory effect on glutamate uptake may be related, at least in part, to the ability of this compound to oxidize thiol groups. ... 

Another line of investigations has been devoted towards the effect of diphenyl ditelluride on Ca influx into rat brain synaptosomes. Since changes in Ca movements can interfere in a variety of neurophysiologic processes, the high neurotoxicity of diphenylditelluride can be linked to its effect on Ca fluxes at the presynapse. In addition to neurotoxic effects, diphenyl ditelluride has been reported as a strong toxic compound. 

Diisobutylaluminium phenyl tellurolate, a highly air- and moisture-sensitive reagent, prepared by reaction of diisobutylaluminium hydride with diphenyl ditelluride, undergoes an in situ addition to a,jS-unsaturated carbonyl compounds, leading to the corresponding jS-phenyltelluroaluminium enolate. This intermediate is hydrolysed by aqueous HCl into jS-phenyltelluro compounds or smoothly affords an aldol reaction with aldehydes to give a-hydroxyalkyl-jS-phenyltellurocarbonyl compounds. 

At present there are few examples of isolable, well-characterized sources of tellurolate anions (RTe-).1 Although insertion of elemental tellurium into reactive metal-carbon bonds has been known for many years, the resulting solutions contain a mixture of compounds in addition to the RTe- species of interest.2 Alkali metal phenyltellurolate salts, prepared via metal reduction of diphenyl ditelluride in liquid ammonia, were first isolated by Klar and co-workers.3 More recently Lange and Du Mont reported the synthesis of the bulky aryl tellurolate (THF)3Li[Te(2,4,6-f-Bu3C6H2)],4 and Sladky described the in situ formation of a bulky alkyl tellurolate via reaction of tellurium with LiC(SiMe3)3.5 Acidification of aryltellurolate anions affords thermally sensitive tellurols (RTeH) that are stable only below room temperature.6... 

Phenyl trimethylsilyl telluride. C6H5TeSi(CH3)3 (1). The tellurosilane is accessible by cleavage of diphenyl ditelluride with sodium followed by reaction with ClSi(CH3)3 (74% yield). It is sensitive to 02 and HzO. 

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