The Gatterman synthesis of biaryls

The yields in the classical variant are rarely as high as that for diphenic acid. However, tetrakis(acetonitrile)copper(l) perchlorate and similar organic solvent soluble copper(l) 

Cu(MeCN)4CI04 4eq. CuCI04-4H20. 75 % MeCN in acetone r. t. /1 h 

Although the copper-catalysed homo-coupling reaction of aryldiazonium salts is still unemployed, the Cohen s work is a good basis for further achievements of this perspective approach. 

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Closely related arylation to Pschorr reaction is the Gatterman synthesis of biaryls (II) which involves the coupling reaction of two aryldiazonium salts (III) by the influence of copper or copper(I) salts [97,98], Scheme 24. 

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