Synthesis and study of the anodic behavior of 1,3,4,6-tetraaryl-2ℷ4δ2-thieno[3,4-c]thiophenes

Two heterocyclic compounds based on the thieno[3,4-c]thiophene structure with four aryl substituents were prepared and their behavior in electrooxidation studied. These tetraarylthieno[3,4-c]thiophenes were synthesized in three steps starting from 1,3-dibenzoylmethane. in the case of 1,3,4,6-tetraphenyl-2lambda(4)delta(2) -thieno[3,4-c]thiophene 1a and from 1,3-bis(4'-methoxyphenyl)propane-1,3-dione in the case of 1,3,4,6-tetrakis(4'-methoxyphenyl)-2lambda(4)delta(2)-thieno[3,4-c]thiophene 1b, a new compound. Both cyclic and hydrodynamic voltamperometric analyses indicate two reversible one-electron oxidation stages for compound 1b, while for compound 1a only the first stage is reversible. The preparative electrooxidation of the two compounds results in the opening of one thiophene ring giving rise to gamma-keto-thioketones.