Bis-phenylethynyl telluride

On the basis that bis-organyl tellurides undergo Te/Li exchange by treatment with an organolithium reagent, if a thermodynamically more stable organolithium moiety is released,bis-(phenylethynyl) telluride has been employed as starting material for the synthesis of diaryl tellurides. ... 

Bis-phenylethynyl telluride (typical procedure To LDA (8 mmol) in THF is added a solution of TeCl4 (0.28 g, 2 mmol) in THF at -78°C, and the mixture stirred at that temperature for 2 h. Phenylacetylene is injected into the resulting orange solution, the mixture is stirred at -78°C for 2 h and then allowed to rise to 0-18°C for an additional 16 h. The mixture is poured into brine, and the organic layer extracted with ether and dried (NaS04). The crude material is purified by SiOj column chromatography (elution with n-hexane/CHjCy, giving bis-phenylethynyl telluride and 1,4-diphenylbutadiyne in yields of 40 and 4%, respectively. 

Diphenyl telluropyran-4-one (typicalprocedure)7° 120 mL (0.12 mol) of a 1.0 M solution of lithium triethylborohydride in tetrahydrofuran are added to 7.65 g (60 mmol) of powdered tellurium under nitrogen, and the mixture stirred at 20°C for 4 h. A solution of sodium ethoxide (prepared from 5.52 g (0.24 mol) of sodium and 240 mL of absolute alcohol) is added to the dilithium telluride, 13.8 g (60 mmol) of bis(phenylethynyl) ketone are dissolved in a mixture of 150 mL of tetrahydrofuran and 150 mL of 1 M sodium ethoxide in ethanol this solution is poured as quickly as possible into the deep-purple-coloured dilithium telluride soluhon. The flask containing the reaction mixture is immediately placed in a water bath at 50°C and the temperature slowly increased over 30 min until ethanol begins to condense on the side of the flask. The water bath is removed and the mixture is stirred overnight at 20°C. Dichloromethane (400 mL) is then added, the resultant mixture is washed with 800 mL of water, and the organic phase is separated and concentrated to an oil. The oil is dissolved in 600 mL of dichloromethane, and the solution is filtered through a pad of sand. The filtrate is washed with 200 mL of 2% aqueous sodium chloride soluhon, dried with anhydrous sodium sulphate, filtered and evaporated. The brownish solid residue is triturated with 20 mL of butanenitrile and the fine yellow solid is collected by filtration yield 10.9 g (51%) m.p. 126-129°C (from acetonitrile). 

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