Diarylzinc species

Bolm s in situ generation of diarylzinc species from boronic acids and its application in asymmetric arylations of aldehydes [15]... 

In conclusion, the electrosynthesis of diarylzinc or diheteroaryl zinc species can be achieved with good yields to the reaction conditions described above to the presence of 10 or 20% of catalyst and using the corresponding dibromides or sometimes dichloride reagents. 

Arylzincs are converted to symmetrical biaryls by copper(II) halides [16], as well as by iV-chlorosuccinimide [17]. The method is more important than the homo-coupling of aryllithiums since, in a number of cases, higher yields were obtained, presumably because of more effective transmetallation of intermediate diarylzincs to copper(Il). In this maimer, tetra-ort/zo-bromobiphenyl (434) was lithiated with n-BuLi, and subsequently converted to the zinc species 435, stable at low temperatures. The latter is reacted with copper(ll) chloride to biphenylene 436 in 72% yield, accompanied with formation of intermolecular coupling product 437 in very small amount [16], Scheme 8. In contrast, the direct homo-coupling of bis-lithiated compound 434 with copper(Il) chloride furnished the compound 436 in only 15% yield, with predominant formation of intermolecular coupling product 437 in 61% yield [16],... 

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