Monodisperse Aromatic Oligomers of Defined Structure and Large Size through Selective and Sequential Suzuki Palladium-Catalyzed Cross-Coupling Reactions

Abstract

Several monodisperse aromatic oligomers of defined structure have been prepared through selective and sequential palladium-catalyzed cross-coupling reactions. The scope of the synthesis was evaluated in terms of (i) molecular size with materials ranging from relatively small sizes (5 and 6 aromatic rings) through to intermediate sizes (9 and 10 aromatic rings), right up to a monodisperse oligomer with 21 aromatic rings, and (ii) variety of molecular structure, with materials including benzene and thiophene core units, and peripheral substituents, including octyloxy, fluoro, and cyano to aid solubility and enhance polarity. The synthetic strategy involved the preparation of Grignard reagents and organolithium derivatives to generate arylboronic acids, which were then involved in selective Suzuki palladium-catalyzed cross-couplings to generate intermediate bromides. These intermediates were either converted into boronic acids and then used in further couplings or used directly in further couplings. The scop...