Anthradithiophene-based organic semiconductors through regiodirected double annulations

Anthradithiophene (ADT), a thienoacene composed of five fused aromatic rings, is a promising building block for realizing π-conjugated systems for organic electronics, but its use remains rare because of its limited synthetic accessibility. We report here an innovative double annulation protocol combining, in one pot, a direct arylation and cross aldol condensation, for the regiospecific construction of π-extended angularly fused ADT-based scaffolds. The multi-gram scale synthetic protocol does not require lengthy chromatographic purifications, leading to very low values for E factors, warranting scalability and sustainability of the overall process. The ADT-based compounds can be efficiently derivatized on the α-positions of the fused thiophene residues. Two types of π-extended small molecules could be synthesized and characterized. Devices built with the p-type small molecule showed good hole mobilities independently from the applied field.