Palladium-Catalyzed C−H Homocoupling of Bromothiophene Derivatives and Synthetic Application to Well-Defined Oligothiophenes

Synthesis of oligothiophenes of well-defined structures that possess 2−8 thiophene units is performed with a new synthetic strategy involving C−H homocoupling of bromothiophenes and cross-coupling with organostannanes. Tolerance of the carbon−bromine bond to the palladium-catalyzed C−H homocoupling results in oligothiophenes bearing C−Br bonds at the terminal thiophene rings, which allow further transformation by the catalysis of a transition-metal complex.