From organyl tellurolates and arylating agents

The arylation of organyl tellurolates, restricted first to aryl halides activated by electron-withdrawing groups,2 or requiring special conditions such as heating in HMPA in the presence of Cul, or photostimulation in liquid ammonia,ijggjj achieved successfully with non-activated aryl halides under normal conditions.  

Methyl o-methoxyphenyl telluride (typical procedure). To a frozen solution of MeTeLi (50 mmol) is added o-bromoanisole (9.3 g, 50 mmol). The mixture is allowed to warm at room temperature, stirred for 1.5 h and then quenched with deoxygenated H2O (100 mL). The organic product is extracted with ether (3X50 mL), the organic extracts dried (MgS04) for 16 h and evaporated, and the residue is distilled under vacuum, giving the telluride as a pale yellow oil (9.3 g (74%)). 

Arenediazonium salts - as well as arenesulphonylazo compounds have also found a use as arylating agents for arene tellurolates. 

Reaction of diarylditellurides with arenediazonium salts (typical procedure). p-Methoxy phenyl p-tolyl telluride. With heating and stirring in an atmosphere of nitrogen, sodium tetrahydroborate was added in small portions to a solution of 9.4 g of bis(p-methoxyphenyl) ditelluride in a mixture of 50 mL of ethanol and 15 mL of benzene until the solution was decolourized completely (1.5 g was required). Then 8.24 g of p-toluenediazonium fluo-roborate was added rapidly and the mixture was stirred for 1 h and poured into dilute HCl. The oil formed was extracted with ether, and the extract was washed with water and dried over CaCl2. Ether was evaporated, and the residue was dissolved in benzene and chromatographed on alumina (eluent hexane). After the evaporation of hexane, 4.8 g (36%) of the telluride was isolated, m.p. 64-64.5°C (hexane). 

Trimethylsylilmethyl telluride generated in situ from methyllithium and trimethyl-chlorosilane can be used instead of the tellurolate in the latter reaction.  

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