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Paper | Special issue | Vol 82, No. 1, 2010, pp.505-529
Published online, 2nd June, 2010
DOI: 10.3987/COM-10-S(E)23
Iterative Extension of Thiophene Ring Leading to Head-to-Tail-Type Oligothiophenes via Stepwise CH Arylation and Halogen Exchange Sequence

Shunsuke Tanba, Atsushi Sugie, Naoyuki Masuda, Daiki Monguchi, Nagatoshi Koumura, Kohjiro Hara, and Atsunori Mori*

*Department of Chemical Science and Engineering, Faculty of Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

Iterative extension of the thiophene ring unit leads to oligothiophenes. The coupling reaction at the CH bond of thiophene with halo-thiophene occurs at the 5-position of 2-bromothiophene with 2-iodothiophene in the presence of a palladium catalyst and AgNO3/KF as an activator to give the corresponding bithiophene, whose carbon-bromine bond remains. Halogen exchange converts the bromine atom to iodide, which also allows further reaction to form thiophene-thiophene bond. Oligothiophenes are obtained by repeating such sequense.