A Convenient Preparative Method of Dibromoterphenyl and Bis(bromophenyl)diene Monomers Using Zirconacyclopentadienes

Zirconacyclopentadienes prepared from 4,4ʹ-dibromodiphenyldiynes or 1-(4ʹ-bromophenyl)-1-alkynes reacted with dimethylacetylene dicarboxylate in the presence of CuCl afforded polyphenylene monomers which contain three benzene rings. Hydrolysis, chlorination with NCS, or allylation of the zirconacyclopentadienes gave a variety of polyphenylenedienylene monomers. Polymerization of these monomers using the system NiCl2(PPh3)2 (cat.)/Zn produced the corresponding polymers.