Homo-coupling reactions of miscellaneous arylmetallic reagents to biaryls

Homo-coupling reactions of miscellaneous arylmetallic reagents to biaryls 

However, practical synthetic method for performing the homo-coupling of arylboronic acids to the respective symmetrical biaryls is accomplished with copperfll) nitrate as an ultimate oxidant in good to high yields, Table 8. 

Diaryldialkylstannanes also smoothly react with Cu(N03)2 to give the homo-coupled products in good to excellent yields. Table 9. Atempts to carry out the cross-coupling reactions of two different diarylstannanes resulted in the formation of all three possible biaryls in practically statistic ratio [30]. 

The reaction is facilitated by the polar solvents, e.g. DMF [33], DMSO [33], or acetonitrile [32], and tetraalkylammonium fluorides as organic solvent-soluble sources of fluoride anion, which convert the aryldimethylsilicon chlorides to the respective fluorides. The latter smoothly undergo the transmetallation reaction from silicon to copper, what finally resulted in the formation of biaryls in high yields. Beside copper(I) iodide, other Cu(I) salts such as CuCl, CuBr and CuOTf have been employed, however, Cul works the most efficiently with ArSiMe2X [32], whereas copper(I) chloride and triflate are suitable in the reactions with ArSiEtF2, and ArSiFj 

The electrophilic aromatic substitution reaction of less reactive arenes such as benzene with tellurium(IV) chloride can be accelerated by adding the Lewis acid, e.g. aluminum chloride. Namely, refluxing the mixture of TeCU and AICI3 (3 eq.) in 

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