Divinyl ditellurides

In neutral conditions, the reduction of the divinyl ditellurides to the corresponding dialkyl ditellurides occurs preferentially to the hydrotelluration reaction. 

By treating the vinylic magnesium tellurolates with air while stirring, instead of with alkyl bromides, divinylic ditellurides are formed. ... 

Divinylic ditellurides (generalprocedure) Elemental Te (12.7 g, 100 mmol) is added at once to a stirred solution of the vinylic magnesium bromide (0.11 mol) in THE (150 mL) under N2. The mixture is refluxed for 30 min with stirring, allowed to reach room temperature, then stirred for 1 h in the presence of air (by opening the apparatus). Deposition of some Te is observed during the oxidation process. The mixture is treated with brine. 

The divinylic ditellurides, obtained as described, are converted into alkyl vinyl tellurides by reduction with AILiH4 followed by alkylation. ... 

Alkyl vinyl tellurides (general procedure) A solution of the divinylic ditelluride (1.0 mmol) in THF (6 mL) is added dropwise, at room temperature under Nj, to AILiH4 (0.09 g, 2.5 mmol) in THF (3 mL). The dark red colour of the ditelluride disappears. The resulting mixture is treated with butyl bromide (0.3 g, 2.2 mmol) and stirred for 15 min. Then H2O (0.5 mL), 10% aqueous NaOH (0.5 mL) and HjO (0.5 mL) are added in sequence. The product is extracted with ether (3x10 mL). The extract is washed with brine, dried (MgS04) and evaporated, giving the product as a yellow oil. 

Organo Vinyl Tellurium (from Vinyl Tellurium Iodides) A solution of the vinyl tellurium iodide, prepared by addition of 0.25 g (1.0 mmol) iodine in benzene to the divinyl ditelluride (1.0 mmol) in 5 ml tetrahydrofuran at 0° under nitrogen, is added dropwise to a solution of the organo magnesium bromide in 10 m/ tetrahydrofuran at 0°. The mixture is stirred at 20° for 1 h, hydrolyzed with a saturated aqueous solution of ammonium chloride, extracted with diethyl ether, the extract dried with magnesium sulfate and evaporated. The product is chromatographed on silica gel with petroleum ether (30-60°)/ethyl acetate (9 1) as eluent. The following compounds were prepared in this manner (yields in parentheses are for the reactions with vinyl tellurium iodides) ... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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