Aryl bromides can efficiently react with some metallocenes, typically zirconocene dichloride, in the presence of a palladium/phosphine catalyst system and an appropriate base to produce the corresponding pentaarylated cyclopentadienes.
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-pentaaryl-13-cyclopentadienes in a single preparative step. Derivatives of cyclopentadiene. including di- and trisubstituted cyclopentadienes. and indene are arylated in a similar fashion.
New Aspects of Synthesis and Properties of Arylated Cyclopentadienes
作者:Gerald Dyker、Jörg Heiermann、Masahiro Miura
DOI:10.1002/adsc.200303079
日期:2003.9
method for the synthesis of sterically crowded cyclopentadienes bearing up to five ortho-substituted aryl groups. A maximum of four mesitylene groups can be introduced. While penta(para-xylyl)cyclopentadiene and pentakis(2-chlorophenyl)cyclopentadiene exhibit at least six rotamers in the proton NMR spectrum, only two rotamers are registered for the tetra(2-chlorophenyl)cyclopentadiene; the all-trans