Polymer-Supported Synthesis of Regioregular Head-to-Tail-Coupled Oligo(3-arylthiophene)s Utilizing a Traceless Silyl Linker

• Published in: Journal of organic chemistry Vol. 65; no. 2; pp. 352 - 359
• Main Authors: Briehn, Christoph A, Kirschbaum, Thomas, Bäuerle, Peter
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 28.01.2000; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Science & Technology; LIBRARIES; UV-VISIBLE PROPERTIES; ORGANIC-SYNTHESIS; SOLID-PHASE SYNTHESIS; POLYTHIOPHENES; CHEMISTRY; OLIGOTHIOPHENES; IDENTIFICATION; PHENYLACETYLENE OLIGOMERS; DISCOVERY
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo991188b

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.