Zirconium-Mediated Biphenylation of Dihalobenzenes

Significance

Organozirconium complex 1 reacts with o-dihaloaryl compounds to yield triphenyl­enes, without the requirement for a transition-metal catalyst. Although triphenylene is obtained from the reaction of 1 with o-difluoro- and o-dichloro­benzene, the yields of these reactions are low (2% and 14%, respectively): dibromo- and diiodo­arenes are the optimal reaction substrates. The reaction of 1 with tetrabromoarenes delivers strained tetrabenz[a,c,h,j]anthracene products in moderate yields. Attempts to trap a putative benzyne intermediate with furan did not result in the formation of a cycloaddition product.