From 2-R-Phenyl Alkyl Tellurium Compounds

Suitably substituted phenyl alkyl tellurium derivatives are potential starting materials for the preparation of benzotellurophenes. Two examples of these reactions have been reported in the literature 2-R-carbonylbenzotellurophenes were obtained in 80% yield by refluxing 2-formylphenyl R-carbonylmethyl telluriums in a mixture of pyridine/acetic anhydride .  

2-Carboxybenzotellurophench A mixture of 15.5 g (53 mmol) of 2-formylphenyl carboxymethyl tellurium, 50 ml of pyridine, and 50 ml of acetic anhydride is heated under reflux for 2 h, most of the solvent is then evaporated under vacuum, and the residue is extracted with boiling, 1 molar aqueous sodium hydroxide solution. The extract is neutralized, the precipitate is filtered off, and the solid is recrystallized from ethanol/benzene yield 11.6 g (80%) m.p. 206-208°. 

2-Carboxyphenyl carboxymethyl tellurium refluxed in acetic anhydride yielded 3-acet-oxybenzotellurophene, which, upon hydrolysis with potassium hydroxide, gave 3-hydr-oxybenzotellurophene. According to spectroscopic data, 3-hydroxybenzotellurophene exists in the form of 3-oxo-2,3-dihydrobenzotellurophene. This method of preparing 3-oxo-2,3-dihydrobenzotellurophene is laborious and gives low yields.  

This compound was prepared more conveniently in 36% yield by refluxing butyl 2-diazoacetylphenyl tellurium for 1 h in the presence of copper (II) oxide  

---