Thallium-carbon bonds reactions with

For example, photolysis of a suspension of an arylthallium ditrifluoro-acetate in benzene results in the formation of unsymmetrical biphenyls in high yield (80-90%) and in a high state of purity 152). The results are in full agreement with a free radical pathway which, as suggested above, is initiated by a photochemically induced homolysis of the aryl carbon-thallium bond. Capture of the resulting aryl radical by benzene would lead to the observed unsymmetrical biphenyl, while spontaneous disproportionation of the initially formed Tl(II) species to thallium(I) trifluoroacetate and trifluoroacetoxy radicals, followed by reaction of the latter with aryl radicals, accounts for the very small amounts of aryl trifluoroacetates formed as by-products. This route to unsymmetrical biphenyls thus complements the well-known Wolf and Kharasch procedure involving photolysis of aromatic iodides 171). Since the most versatile route to the latter compounds involves again the intermediacy of arylthallium ditrifluoroacetates (treatment with aqueous potassium iodide) 91), these latter compounds now occupy a central role in controlled biphenyl synthesis. 

Treatment of arylthallium(III) compounds with metal nitrites in trifluoroacetic acid affords the corresponding nitrosoarenes, which are oxidised to the nitroarenes. The reaction was suggested to occur by electrophilic attack of NO+ on the carbon-thallium bond. l ... 

The conversion of a carbon-thallium bond into a carbon-carbon bond has been performed directly only in a relatively limited number of cases formation of aiylcyanides, reaction with nitroalkane salts as well as the reaction with copper acetylides. Other carbon-carbon bond formation reactions have been reported with a carbon-thallium substrate. However, they all involve palladium catalysis, and this is beyond the scope of this book. 147... 

The formation of a carbon-carbon bond by reaction of alkylthallium(III) compounds has been described in the a-nitroalkylation of alkanes. The reaction of alkylthallium (129) with nitroalkane anions leads to the nitroalkyl derivatives (130). In this case, radical intermediates generated by electron transfer activation of the carbon-thallium bond are involved in a non-chain substitution process. 

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