Abstract

Conjugated thiophene-based material are highly desired materials in various fields of organic electronic materials. Poly/oligothiophene are among the most common substrate used in many different organic electronic materials. The general synthesis involves cross-coupling reactions such as Migita-Stille, Corriu-Kumada, Negishi, and Suzuki-Miyaura. These reactions are robust methodologies, but often involves organometallic reagents and produce metallic waste. Direct (hetero)arylation has been proposed as a greener approach for constructing conjugate-polymeric materials. However, for the many thiophene-based materials they suffer from regioselectivity issues and unwanted side-reactions. Alternatively, decarboxylative cross- coupling provides excellent regioselectivity through the carboxylic acid functional group, that has been demonstrated as an excellent synthetic tool for bi-aryl and/or tri-aryl targets. We envisioned utilizing this method as an efficient strategy for constructing a library of oligothiophenes, where it would be complementary to existing methodologies, and provides a greener approach for green energy applications. Herein, we developed improved reaction conditions without the need of base to prepare a library of poly/oligothiophene. The modularity of our new approach is demonstrated with a scope of 25 different type of symmetric oligothiophenes with highlights in synthesizing symmetrical oligothiophenes with up to 10 thiophene units. Furthermore, this method was also applied towards the synthesis of regioregular oligothiophene and polythiophene. Decarboxylative cross-coupling has demonstrated complete chemoselectivity for thiophene-based oligomers through this work and proven as a comprehensive greener approach compared to the existing synthetic methodologies.