EFFICIENT PALLADIUM-CATALYZED SYNTHESIS OF UNSYMMETRICAL DONOR-ACCEPTOR BIARYLS AND POLYARYLS

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, DC6H4C6H4A, 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 {A figure is presented} (n = 3,4). © 1990.