Telluraxanthene oxidation

The second method employed for the synthesis of telluraxanthene is similar to that widely used for the preparation of various tricyclic heterocycles containing one or two heteroatoms. It is based on the interaction of 2,2 -dilithiodiphenylmethane with powdered tellurium, by which reaction telluraxanthene 82 has been prepared in 50% yield [81JOM(205)167]. The reaction apparently proceeds through the intermediate bis(telluro-phenolate) 86 which is oxidized to the heterocyclic ditelluride 87. The latter compound eliminates tellurium from its stericaily strained seven-membered ring and converts to telluraxanthene. This mechanistic scheme seems to be corroborated by the observation that the treatment of lithi-oarenes ArLi usually ends in the formation of diarylditellurides Ar2Te2 (74MI1 83MI2). 

II,H,1). The methylene group of telluraxanthene can be easily oxidized to a carbonyl group, telluraxanthone being the product. 

In fact, the only known method of synthesis of telluraxanthone 94 is that based on the oxidation of telluraxanthene (80KGS1342) or 10,10-dichlorotelluraxanthene [80KGS1342 81JOM(205)167] with potassium dichromate (80KGS1342) or chromic anhydride [81JOM(205)167] in acetic... 

Telluraxanthene was oxidized to telluraxanthone with chromium trioxide or potassium dichromatc1 3 in glacial acetic acid. 

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