Tris telluronium

Figure 36 Anion bridging in (a) solid tris(pentafluorophenyl) telluronium chloride and (b) dimesityl(pentafluorophenylseleno) telluronium hexafluoroantimonate...

Refluxing a mixture of tellurium tetrachloride and 1,3-dihydroxybenzene under an atmosphere of nitrogen produced tris[2,-4-dihydroxyphenyl] telluronium chloride (m.p. 129-131°) in 33% yield1. 

Bis[pentafluorophenyl] tellurium and pentafluorophenyl xenon fluorotrisfpentafluorophe-nyljborate reacted in acetonitrile to give the tris[pentafluorophenyl] telluronium salt1. 

Tris[2-thienyl] Telluronium Bromide3 2.2 g (4.8 mmol) of bis[2-thienyl] tellurium dibromide are added to a Grignard solution prepared from 1.7 g (10 mmol) of 2-bromothiophene in 50 ml of diethyl ether. The mixture is heated under reflux for 2 h, cooled, added to 15 ml of water, and filtered. The filter cake is washed with water and dried in a vacuum dessicator. The dry product is extracted with a large volume of methanol and the product precipitated by concentration of the extract m.p. 244° (253° corrected). 

The cleavage of Te-C (phenyl) bonds was observed in reactions between diphenyl tellurium dichloride and 2-phenylethyl magnesium bromide in a diethyl ether/benzene medium at room temperature. Tris[2-phenylethyl telluronium bromide (m.p. 127°) and chloride (m.p. 135°) were isolated in approximately 40% yield4. 

Tris[2-thienyl] telluronium iodide5 and 4-bromobutyl tetramethylene telluronium iodide [m.p. 176° (dec)]6 were prepared in this manner. This reaction was employed to isolate telluronium salts as telluronium iodides from reaction mixtures obtained by combining tellurium tetrachloride and aryl magnesium bromides (Vol. IX, p. 1080). 

Tris[4-methylphenyl] Telluronium Bromide1 2.0 g (3.5 mmol) of tris[4-methylphenyl] telluronium iodide are dissolvedin 10 ml of methanol, 400 ml of water are added to form a milky suspension, excess silver bromide is added, and the mixture is stirred and heated under reflux for 0.5 h. The hot mixture is filtered, the filtrate is cooled, filtered, and the solid is recrystallized from water m.p. 266° (dec.). 

Dimethyl and methyl phenyl 4,4-dimethyl-2,6-dioxocyclohexylidene tellurium compounds transferred a methyl group to triethylamine, triphenylphosphane, tris[di-methylamino]phosphane, and triphenylarsane. The methyl onium cations were isolated as lelraphenylborates. The alkylidene organo telluronium intermediate was identified by 31P-NMR spectroscopy in the reaction of the ylide with tris[dimethylamino]phosphanc . 

Telluronium Tris-2-thienyl-(Bromide) E12b, 690 (Ar2TeBr2 + Ar —MgBr)... 

Tris[4-hydroxy-2-metfaylphenyl] Telluronium Chloride A mixture of 4.0 g (37 mmol) of 3-melhylphenol and 5.0 g (18 mmol) of tellurium tetrachloride in carbon tetrachloride is heated under reflux in an inert atmosphere for 30 h, and then allowed to cool. The mixture is filtered, the filter cake is washed thoroughly with carbon tetrachloride and benzene, the solid is extracted with acetone, and the residue is dissolved in methanol. The methanol solution is concentrated, the precipitate is collected, dissolved in methanol, and the product reprecipitated by the addition of acetone yield 2.2 g (25%) m.p. 188-192°. 

The reaction of tellurium tetrachloride (9.3 mmol) with pentafluorophenyl lithium (24 mmol) in diethyl ether/hexane solution gave tris pentqfluorophenyl] telluronium chloride (m.p. 188-190°). ... 

Tris[4-hydroxy-2-methylphenyl] Telluronium Bromide An excess of a solution of potassium bromide in methanol is added to a saturated methanolic solution of the telluronium chloride and mixed thoroughly. Diethyl ether is added to the mixture to complete precipitation of potassium chloride and excess potassium bromide. The mixture is filtered, the filtrate is concentrated under vacuum, and the residue is recrystallized from diethyl ether or acetone yield 90%, m.p. 180 183°. 

Di-, tri-, and tetra-substituted 2-azadienes (64) carrying electron-withdrawing groups have been synthesised by the aza-Wittig reaction. A one-pot synthesis of olefins from diorganyltelluride, diazo compounds, and carbonyl compounds in the presence of a Cu(I) catalyst is suggested to involve a Wittig-type reaction of an intermediate telluronium ylide. ... 

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