Tellurides reactions with

Diol cyclic sulfates on reaction with telluride ion (prepared by reduction of elemental tellurium) afford alkenes as products. Thus D-ribofuranoside derivative 33 gives 34 in 72% yield. ... 

Recently, a one-pot method for preparation of 2-aryl-1,5-benzotelluroazepines 60 has been developed based on the reaction of sodium 2-aminophenyltellurolate [from di(o-aminophenyl) ditelluride) with arylpropargyl aldehydes (99MI1). Considering the high affinity of supemucleophilic aryltellurolate anions to a triple bond, one may assume that at the first stage of this reaction arylvinyl tellurides 61 are formed. Cyclization of 61 spontaneously or on silica gel in a chromatographic column forms the heterocycles 60. 

The same reaction can be performed under even milder conditions with tellurides, i.e. they react at 80 °C without a catalyst107 (equation 81). 

The catalytic cycle for the thiolperoxidase and haloperoxidase-like activity of diorganoselenides and tellurides is summarized in Fig. 25. Stopped-flow spectroscopy has been used to elicit mechanistic details of the cycle. " " Following oxidation to the selenoxide or telluroxide, the catalytic cycle for thiolperoxidase-like activity is shown in Fig. 21. The details of the haloperoxidase-like cycle are not as well defined. Using dihydroxytellurane 52 as a substrate, the addition of 0.5 M sodium iodide in pH 6.8 buffer gave a fast reaction with a second-... 

The use of sodium dithionite (Na2S204) and thiourea dioxide (TUDO HN=C(NH2)S(0)0H) has been introduced later as a reducing agent for the preparation of sodium telluride in an aqueous medium, followed by reaction with n-alkyl halides to give dialkyl teUiirides. - ... 

The normal low reactivity of aryl halides towards nucleophilic reagents is not generally observed in their reaction with alkali tellurides. The observed reactivity seems to be... 

Another method that uses arenediazonium fluoroborates to prepare diaryl tellurides is the reaction with potassium tellurocyanate. Aryl teUurocyanides are postulated as intermediates. 

The low reactivity of aryl halides towards nucleophilic reagents makes their reaction with sodium ditelluride unattractive for the preparation of diaryl ditellurides. Low yields are obtained, like the similar reaction with sodium telluride (see Section 3.1.2.1). 

The reaction with ethyl- and cyclohexytmercury chlorides requires heating for 24 h. 3.9.4 By addition of halogens to diorganyl tellurides... 

Sodium telluride, obtained by heating elemental tellurium with sodium hydride in DMF, reacts similarly, leading to symmetrical divinylic tellurides (compare the similar reaction with aryl iodides, see Section 3.1.2.1). 

Treatment with water gives the corresponding Z tellurides. Reaction with BuSeBr, iodine and A -bromosuccinimide (NBS) gives respectively Te-Se ketene acetals, a-iodo- and a-bromo vinyl tellurides as mixtures of Z and E stereoisomers (in contrast with the total retention of configuration of the above-discussed Zr/Te exchange reactions). The acylation was effected with acylchlorides in the presence of Cul. ... 

Allenyl tellurides can be submitted to Te/Li exchange and subsequent reaction with aldehydes, giving homopropargylic alcohols. ... 

Method B - with NafTe. A mixture of Te (0.64 g, 5 mmol) and NaBH4 (0.45 g 12 mmol) in DME (20 mL) is heated at 80-90°C under N2 for 30 min, giving an almost colourless suspension (which has been proved to be Na2Te by reaction with 1-bromobntane to give dibntyl telluride). Methyl benzoate is added, and after heating at 80-90°C for 20 min the mixtnre is worked up as for method A, giving pnre benzoic acid (0.99 g (90%) m.p. 121-122°C). 

Similar reactions with vinyl tellurides will be discussed in Section 4.9.3.5. 

In the case of symmetrical divinyl tellurides, the displacement of both vinyl groups is achieved by employing 2 equiv of n-butyllithium. Aryl vinyl tellurides give a mixture of products, since both Ar-Te and vinyl-Te bonds are transmetallated on reaction with n-BuLi, leading to vinyl- and aryllithiums. The butyl vinyl tellurides give only the desired vinyl-lithiums. The reactions are stereospecific with retention of the C=C bond geometry. °... 

The first reported radical reaction promoted by tellurium reagent was probably the conversion of allylic halides into the coupled 1,5-dienes by treatment with telluride anions. The reaction, which gives the best results when employing the reagent prepared in situ from elemental tellurium and lithium triethylborohydride, proceeds through the intermediacy of the thermally unstable bis-allylic telluride followed by extrusion of tellurium and coupling of the formed allylic radicals. 

The reductive chemoselective bis-silylation of quinones was afforded by thermal reaction with silyl tellurides. ... 

The procedure is based on the reaction of lithinm ethynyltellurolates (generated by the successive treatment of acetylenes with n-BuLi and elemental tellnrinm) with iodochloromethane giving ethynylchloromethyl tellurides. Subseqnent reaction with lithinm tellnride forms lithinm(ethynyltelluro) methane tellurolates which cycUze via an intramolecnlar addition of the tellnrolate to the ethynyltelluro moiety. ... 

Reaction with tellurium powder in alkaline solution yields red crystalline zinc telluride, ZnTe. 

Telturoxide elimination.2 Tellurides are converted to alkenes by reaction with chloramine-T, presumably via the adduct a (equation I). This elimination proceeds In low yield with r-butyl hydroperoxide. 

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. 

When the allylic alcohol is the desired product of the kinetic resolution process, the accompanying epoxy alcohol also may be converted to the desired allylic alcohol by the two-step sequence shown in Scheme 6A. 1. The epoxy alcohol, after separation from the allyl alcohol, is mesylated and then subjected to reaction with sodium telluride, which effects the transformation of epoxy mesylate to the allylic alcohol with inversion at the asymmetric carbinol center [ 115e]. Preliminary results suggest that the rearrangement follows this pathway only when the epoxy alcohol is unsubstituted at the 3-position. 

The addition of telluride anion to l-(trimethylsilyl)penta-l, 4-diyn-3-ones apparently represents a general method for the preparation of 2-substituted l-telluracyclohexa-2,5-dien-4-ones 22 (92MI3). In actual fact, the reaction of l-(trimethylsilyl)-5-phenylpenta-l,4-diyn-3-one with telluride anion affords 22 (R1 = Ph, R2 = H) in 38% yield, whereas only 12% of this compound is attained in the reaction with l-phenylpenta-l,4-diyn-3-one (87JOC3662). 

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