Polymer-supported synthesis of regioregular head-to-tail-coupled Oligo(3-arylthiophene)s utilizing a traceless silyl linker
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.
Briehn
CA
Abteilung Organische Chemie II (Organic Materials and Combinatorial Chemistry), Universitat Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany.
Kirschbaum
T
Bauerle
P