10- - -perchlorate telluraxanthene

Treatment of telluraxanthene with phenyllithium in benzene gives 9-lithiotelluraxanthene in 60% yield (80KGS1342). Reaction with trityl perchlorate converts 82 into 10-telluroniaanthracene perchlorate (Section... 

A less common approach to the tellurachromylium and telluraxanthyl-ium cations is based on dehydrogenation of 2//-tellurachromene 53 (86KGS1570) and telluraxanthenes 82 (81KGS343) with trityl perchlorate. 

A telluronium salt could not be obtained from telluraxanthene and methyl iodide. However, the telluronium perchlorate was formed in high yields when silver perchlorate was added to the reaction mixture3. 

MethylteIluraxanthylium Perchlorate1 A solution of 2.08 g (10 mmol) of silver perchlorate in 50 ml of acetonitrile is added dropwise to a solution containing 2.94 g (10 mmol) of telluraxanthene and 11.4 g (5 ml 80 mmol) of methyl iodide. The mixture is stirred and heated under reflux for 30 min, cooled, the precipitated silver iodide is removed by filtration, and the filtrate is evaporated to leave colorless crystals that melt and explode at 183°. 

Refluxing telluraxanthenes with triphenylcarbenium perchlorate in trifluoroacetic acid produced telluraxanthylium perchlorates3. 

Methoxyphenyl)-tclluraxanthylium Perchlorate1 7 ml (70 mmol) of 70% perchloric acid are added dropwise to a stirred solution of 4.16 g (10 mmol) of 9-hydroxy-9-(4-methoxyphenyI)-telluraxanthene in 60 ml of absolute diethyl ether. The precipitate is filtered, washed with absolute diethyl ether, and the black-violet crystals are dried at 20° in air. The substance decomposes explosively when melted in a capillary at 207°. 

The telluraxanthylium perchlorates are soluble in trifluoroacetic acid. They react with acetic acid, acetone, and nitromethane1. For the reduction of telluraxanthylium perchlorates to telluraxanthenes see p. 833. 

The methylation of phenoazatellurin and telluraxanthene succeeded only when silver perchlorate was present in the reaction mixture. 

Methylphenyl)-telluraxanthylium perchlorate was reduced by lithium aluminum hydride to 9-(4-methylphenyl)-telluraxanthene. ... 

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