Electrosynthesis of Dissymmetric Biaryls

4-phenylquinoline derivatives are obtained in moderate to good yields. It should be pointed out that the choice of an iron rod anode was of crucial importance for the efficiency of this electrochemical process. The electrolysis is conducted until complete disappearance of the starting 4-chloroamine. 

Under the same conditions, the use of an iron anode is also necessary for the reductive dimerization of aryl halides (p-MeOPhBr, p-EtOCOPhBr, etc.). With a Mg or A1 sacrificial anode, or if electrolysis is conducted in a divided cell, aryl bromide (ArBr) is principally converted to the reduction product (ArH) [22]. 

This very versatile process compares favorably with the procedure described by Lemaire [24] since the excess of the more reactive aromatic halide does not bring additional difficulties in the separation steps. Obviously, the large excess of the more reactive aryl halide induces the formation of the large amount of the corresponding homocoupling biaryl. In most cases, this corresponding symmetric biaryl, even as the major product in the medium, does not influence the extraction and the purification of the unsymmetrical biaryl Ari-At2. The symmetric biaryl stemming from the less reactive halide only occurs as traces. 

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