title: Polymer-supported synthesis of regioregular head-to-tail-coupled Oligo(3-arylthiophene)s utilizing a traceless silyl linker
abstract: The solid-phase synthesis of regioregular head-to-tail-coupled oligo(3-arylthiophene)s has been achieved in high yield and purity by using a traceless silyl ether linkage. In the first step, the solution-phase synthesis of this class of conjugated oligomers was investigated. Benzyl alcohol was chosen to serve as a mimic for the anchoring group of the hydroxymethyl-substituted polystyrene matrix. The development of a novel regioselective iodination process for silyl-protected thiophenes faciliates the successful application of the solution-phase protocol to the solid phase. Satisfactory loading was obtained by reaction of chlorosilyl-functionalized 3-arylthiophene with hydroxymethyl polystyrene in the presence of imidazole. The suitability of the following iterative halogenation and Suzuki cross-coupling sequence is illustrated by the preparation of a quater(3-arylthiophene), the first regioregular head-to-tail-coupled oligothiophene that is synthesized on solid support. Removal of the conjugated oligomers from the solid support could be effectively achieved by treatment with tetrabutylammonium fluoride.
authors.affiliation: Abteilung Organische Chemie II (Organic Materials and Combinatorial Chemistry), Universitat Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany.
authors.initials: CA
authors.lastname: Briehn
authors.initials: T
authors.lastname: Kirschbaum
authors.initials: P
authors.lastname: Bauerle