Microwave assisted synthesis of functional oligothiophenes

The increasing use of oligothiophenes in nano(bio)technology requires the preparation of large amounts of compounds with high and reproducible levels of purity. Therefore, the demand for practical, mild and efficient synthetic routes to oligothiophenes is continuously growing. This chapter describes two promising 'enabling techniques', namely microwave irradiation and solid phase catalysis and their combination, for the preparation of oligothiophenes with improved (opto)electronic functionalities. An innovative procedure, based on microwave assisted heterogeneous Pd catalysis is described. Such new, efficient and clean methodology smoothly afforded the preparation of oligothiophenes in high yields (up to 87% isolated yield, 30-100 minutes). The approach combining a very efficient reaction, i.e. the Suzuki Miyaura cross coupling, with improved catalyst separation, results more convenient and greener than any of the existing methodologies. Thienyl iodides or activated bromides can be employed as starting materials and KF as the base. The microwave reaction can be carried out in aqueous ethanol and the heterogeneous catalyst can be easily removed from the reaction mixture by filtration and reused in consecutive reactions (up to 4 times).