Institution: | Ecole Normale Supérieure, Laboratoire de Chimie, UA CNRS 1110, 24, Rue Lhomond, 75231 Paris Cedex 05 France Laboratoire de Marcoussis, Route de Nozay, 91460 Marcoussis France |
Abstract: | 4,4′-Unsymmetrically substituted biphenyls can be synthesized by cross-coupling reactions of substituted aromatic organometallic reagents and aromatic halides catalyzed by palladium complexes. This two-step method from commercially available aromatic halides has been used for the synthesis of a series of donor/acceptor para-substituted biphenyls, D---C6H4---C6H4---A, where D is an electron donor group and A an electron acceptor group, which are of interest as liquid crystal precursors and as having potential in non-linear optics. Biaryls in which the donor-phenyl moiety is replaced by a 2-furyl or 2-thienyl can be synthesized similarly. The method can also be used for the convergent synthesis of previously unreported unsymmetrically substituted polyparaphenylenes
(n = 3,4). |