Dendritic and hyperbranched polyphenylenes via a simple Diels-Alder route

Article abstract of DOI:10.1016/S0040-4020(97)00967-8

A Diels-Alder route to dendritic and hyperbranched polyphenylenes, based on hexa(penta)phenylbenzene units, is described. Using ethynyl-, propynyl- and phenylethynyl-substituted tetraphenylcyclopentadienones 1c-e, hyperbranched polymers with molecular weights M(w) as high as 107,000 g mol^{- 1} are obtained. The new dendritic polyphenylene 5c is synthesized starting from 3,3',5,5'-tetraethynylbiphenyl (2c) via a repetitive Diels-Alder- deprotection sequence, employing tetraphenylcyclopentadienones 1a and 1b.