Tellurolate anion

Actually, the method of choice for the preparation of organyl tellurolate anions is the reduction of diorganyl ditellurides with reducing agents. 

The tellurolate anion formed can be alkylated in situ, giving alkyl aryl tellurides, if the above reaction is effected in the presence of a phase transfer catalyst. Otherwise, performing the reaction in the presence of the reducing agent TUDO a telluride yield near to quantitative is generated, owing to the reduction of the aryl tellurinate anion to aryl tellurolate. ... 

From organyl tellurolate (and telluride) anions and vinyl bromides... 

From vinylic tellurolate anions and alkyl halides... 

Organyl tellurolate anions effect 1,4-additions to acetylenes bearing electron-withdrawing groups such as acetylenic ketones, aldehydes, esters, diacetylenic ketones, " as well as acetylenic phosphonates and sulphones giving 2-substituted vinyl tellurides with Z configuration. 

The reduction of acetylenic tellurides to the vinylic ones is achieved by treatment with NaBH4 in EtOH. The formal unusual reduction of the carbon triple bond by NaBH4 can be rationalized involving the attack of a hydride ion to the tellurium atom producing a tellurol and an acetylenic anion followed by the addition of the tellurolate anion to the acetylene, DIBAL-H has later been employed as a reducing agent. ... 

Since the starting tellurides are easily prepared from alkyl hahdes or epoxides by displacement with tellurolate anions (see Section 3.1.3.2), the overall sequence constitutes a mild reduction of these substrates and is advantageous over the analogous reductions of selenides, which require more severe conditions (a temperature of 120°C is necessary). 

Acyl- and aroyllithiums are generated by submitting telluroesters, easily accessible from the corresponding acid chlorides and tellurolate anions (see Section 3.11), to the above-described lithium-tellurium exchange reactions. ... 

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... 

Tellurolate anions possess the highest nucleophilicity in the series of analogous chalcogen derivatives. The same is true for diorganyl tellurides compared to their respective diorganyl sulfides and selenides. 

Based on the extremely high nucleophilicity of the tellurolate anions, a general approach to the synthesis of the 1,3-ditelluroles 50 was developed (82TL1531) that involves the following sequence of reactions. 

A number of methods developed for the preparation of tellurantrene are based on reactions stipulated by the high nucleophilicity of tellurolate and telluride anions. One such method allowing the preparation of tellurantrene in 50-60% yield employs coupling benzene-1,2-ditellurolate (see Section III,H, 1) with 1,2-diiodobenzene (90KGS137 91KGS1203). 

The products present the (Z)-stereochemistry preferentially, in view of the /ra r-addition of the tellurolate to the triple bond. In some cases, mixtures of (Z)- and ( )-olefins are obtained due to equilibration of the intermediate vinyl anion, as a consequence of the nature of the tellurolate or the electrophile.151 By using alkynes 70 bearing an internal electrophile, the cyclic product 71 is formed (Scheme 42). 

The vinylic substitution by tellurolate anions has not been extensively investigated. It is, however, an efficient method for synthesizing vinylic tellurides of defined stereochemistry. (E)-/3-bromostyrene 79 reacts with organo-tellurolate anions to give ( )-vinylic tellurides 80 (Scheme 49).34,144... 

The vinylic substitution was investigated with five different tellurolate anions, "BuTeLi 85a, sBuTeLi 85b,... 

The bis[triphenylphosphoranylidene]ammonium salt of the anionic hydridoundecacar-bonyltriosmate cluster reacted with bis[4-methoxyphenyl] tellurium dichloridc in dichloro-methane to form in 7 percent yield a neutral triosmium cluster with one bridging 4-methoxybenzene tellurolate group2. 

Figure 13 The discrete tellurolate anions in (a) (Ph4P)(TeTh) (Th = 2-thienyl, C4H3S) and (b) [K(18-crown-6)][Te 2,4,6-(Me2CH)3 C6H2 ] ...

Anionic cycloaddition reactions of a,j8-unsaturated selenolates and tellurolates in the synthesis of selenophene, tellurophene, and 1,3,4-sele-nadiazine derivatives 87UK267. 

The analogy between phenyl thiolate (Ph-S ) and ferrocenyl thiolate (Fc-S ) anions leads to the expectation that many compounds containing ferrocenyl thiolate units as either substituents or ligands should exist. This is indeed the case and, although with fewer examples, is also true for ferrocenyl selenolate and tellurolate. Similarly, l,T-ferrocenylene dithiolate compounds (which correspond to o-phenylene dithio-lates) are known, together with the analogous l,r-ferrocenylene diselenolates and ditellurolates. 

Many of these complexes were purified by chromatography. The pure compounds are sensitive towards atmospheric oxygen. The bare tellurium atoms in these complexes can be protonated alkylated with methyl iodide, methyl lithium triethyloxonium tetrafluoroborate or methyl trifluoromethylsulfonate and reacted with diazoalkanes to produce complexes with coordinated telluroformaldehyde or telluroacetone. The anion [O = MoTeJ combined with dimethyl acetylenedicarboxylate to produce a tellurolate-containing molybdenum compound ... 

S-Aryltelluro vinyl aldehydes and ketones have been prepared by treating j -chlorovinyl carbonyl compounds or /(-acylvinyl triethyl ammonium chlorides with arene tellurolate anions. ... 

Carbohydrate anisyl tellurides are easily prepared by treatment of the corresponding mesylates or tosylates with the anisyl tellurolate anion. By irradiation of these tellurocarbohy-drates in the presence of M-acetoxythiopyridone and the electrophilic olefin, the tandem adduct is formed. The oxidative elimination of the thiopyridine moiety leads to the trans-olefins. ... 

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