Sodium ethynyl tellurolates

Methyl phenylethynyl telluride (typical procedure). To NaNH2 (from 6.0 g, 0.26 mol Na) in liquid NHj (250 mL) is added phenylacetylene (25 g, 0.25 mol) dropwise, and then Te powder (30 g, 0.24 mol) in small portions, stirring well for 30 min. Methyl iodide (36 g, 0.25 mol) is added over 20 min to the tellurolate solution. The NHj is then evaporated, the residue extracted with ether and the ether solntion washed with HjO and dried (MgS04). The residue is distilled under vacnum, giving the product (28 g (46%) b.p. 122-124°C/2 torr). 

Lithium butyl tellurolate reacts with phenylbromoethyne to give butyl phenylethynyl telluride  

Otherwise a variety of acetylene tellnrides have been prepared by the reaction of lithinm ethynyl tellnrolates with alkyl halides. 

Phenyl(alkyltelluro)acetylenes (general procedure) n-BuLi (1.35 M in hexane, 22.2 mL, 30 mmol) is added dropwise to phenylacetylene (3.10 g, 30.0 mmol) in THF (15 mL) at 0°C nnder N2. After stirring for 5 min at 0°C, elemental Te (3.90 g, 30.0 mmol) is added and the mixtnre reflnxed nntil the Te disappears ( 30 min). The heat source is removed and the alkyl halide (30 mmol) is added. The mixtnre is stirred for 40 min at room temperatnre, then dilnted with ether (60 mL), washed with brine and the layers separated. The organic phase is dried (MgS04), evaporated and the residne purified by Si02 flash chromatography (elution with hexane). 

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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>. 

Sodium borohydride cleaved the Te—ethynyl bond in alkyl and aryl phenylethynyl telluriums with formation of phenylacetylene and sodium alkano tellurolates ... 

The addition of sodium or lithium tellurolates to carbon-carbon triple bonds can occur intramolecularly when an ethynyl group is suitably located within the molecule to allow the formation of a tellurium-containing heterocyclic compound3,4. 

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