Arylthallium trifluoroacetates preparation

The 1,1-dimetallic compounds, R2C(SnMe3)ZnBr, were oxidized by dry air at —10 to 0°C in the presence of Me3SiCl to give aldehydes or ketones, R2C=0. In a related indirect method, arylthallium bis(trifluoroacetates) (prepared by 12-21) can be converted to phenols by treatment with lead tetraacetate followed by triphenylphosphine, and then dilute NaOH. Diarylthallium trifluoroacetates undergo the same reaction. ... 

Aryl iodides and fluorides can be prepared from arylthallium bis(trifluor-oacetates) (see 12-21), indirectly achieving the conversions ArH —> Arl and ArH ArF. The bis(trifluoroacetates) react with KI to give Arl in high yields. Aryllead triacetates, ArPb(OAc)3, can be converted to aryl fluorides by treatment with BFs-etherate. ... 

Thallium(III), particularly as the trifluoroacetate salt, is also a reactive electrophilic metallating species, and a variety of synthetic schemes based on arylthallium intermediates have been devised.75 Arylthallium compounds are converted to chlorides or bromides by reaction with the appropriate cupric halide.76 Reaction with potassium iodide gives aryl iodides.77 Fluorides are prepared by successive treatment with potassium fluoride and boron trifluoride.78 Procedures for converting arylthallium compounds to nitriles and phenols have also been described.79... 

The formation of iodobenzene by treatment of phenylthallium(III) compounds with potassium iodide was reported, without experimental details, by Challenger et al in the 1930 s. 2,113 jhe potential and synthetic interest of this iododethallation reaction was extensively studied by McKillop and Taylor in the early 1970 s.8 7-89 Although arylthallium(III) compounds prepared by reaction of the arenes with thallium tris(trifluoroacetate) (84) can be isolated, they can also be directly converted into aryl iodides by addition of aqueous potassium iodide to the thallation reaction mixture. An intermediate arylthallium(III) diiodide (91) was suggested to be formed and to decompose intramolecularly to lead to the aryl iodide. ... 

The aryl chlorides and aryl bromides are easily prepared by treatment of the arylthallium(III) bis(trifluoroacetates) with the corresponding copper(I) or copper(II) halides. The best yields were obtained with the copper(II) halides in dioxane under reflux. 2 These reactions have been successfully applied by Somei et al to the synthesis of indole derivatives by reaction of the arylthallium compounds with copper(II) salts in DMF. 127,133,134... 

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