From 4-Thioxo-4-tellurines

Refluxing solutions of 2,6-diorgano-4-thioxo-4//-tellurins in toluene in the presence of copper yielded 4-(2,6-diorgano-4/f-tellurin-4-ylidene)-2,6-diorgano-4 f-tellurins  

6-Diplienyl-4/r-telluriii-4-ylidene)-2,6- iiphenyl-4A-telluriii Equal amounts (w/w) of 2,6-diphenyl-4-thioxo-4//-tellurin and copper powder are added to toluene (5 m//mmol thione) and the mixture is heated under reflux for 1.5 h. The hot reaction mixture is filtered through a 5 cm pad of Celite, the pad is washed with dichloromethane, and the combined filtrate and washings are concentrated. The resultant precipitate is collected and the product (which is much less soluble in hot acetonitrile than the thione) is purified by fractional recrystallization from acetonitrile yield 66% m.p. 274°. 

When the reaction was carried out in refluxing xylene in the absence of copper, a mixture (45 55) of the S. S-compound and the S. re-compound was obtained.  

6- Diphenyl-4-ethoxy-l-tellurinium fluorosulfate reacted with 2,2-dimethyl-4,6-dioxo-1,3-dioxane (Meldrum s acid) to give 4-(2,2-dimethyl-4,6-dioxo-l,3-dioxane-5-ylidene)- 

2-Dlmethyl-4,6-dioxo-l,3-dioxane-5-ylidene)-2,6-diphenyl-4//-tellurin 1.44 g (10 mmol) of Meldrum s acid are dissolved in 25 ml of pyridine, 5.0 g (10 mmol) of powdered 2,6-diphenyl-4-ethoxytellurinium fluorosulfate are added, and the dark red solution is immediately concentrated under vacuum. TTie residue is chromatographed on 100/200 mesh Florisil with dichloromethane as the mobile phase yield 4.0 g (80%) m.p. 199-201°. 

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