Palladiumkatalysierte Dominoarylierung substituierter und anellierter Cyclopentadiene
Cyclopentadiene and metallocenes, typically zirconocene dichloride, are suitable substrates for multiple arylations with aryl bromides in palladium-catalyzed reactions. Thus various aryl bromides bearing either an electron-donating or an electron-withdrawing substituent can react with these substrates to afford the corresponding 1,2,3,4,5-pentaarylcyclopenta-1,3-dienes in a single preparative step. Derivatives of cyclopentadiene, including di- and tri- substituted cyclopentadienes, and azulene are arylated in a similar fashion. Transformations at the functional groups of the pentaarylcyclopentadienes result in pentapodal dendrimer-like systems and sterically demanding stilbenes. The synthesis of conjugated organic oligomers containing pentaarylcyclopentadien units with molecular weights up to 4500 g/mol and electrical conductivities from about 9.6·10E-8 S/cm were achieved by intermolecular McMurry-coupling.