Synthesis and Redox Behavior of 1,3-Bis(methylthio-) and 1,3-Bis(phenylthio)azulenes Bearing 2- and 3-Thienyl Substituents by Palladium-Catalyzed Cross-Coupling Reaction of 2- and 6-Haloazulenes with Thienylmagnesium Ate Complexes

摘要

Preparation of thienylazulenes 3-6 was established by the palladium-catalyzed cross-coupling reaction of the corresponding haloazulenes with thienylmagnesium ate complexes, which were readily prepared from the corresponding bromothiophenes. The reaction of 3-6 with several sulfoxides in the presence of Tf2O, followed by treatment with triethylarmine afforded the corresponding 1,3-bis(methylthio)- and 1,3-bis(phenylthio)-2- and 6-thienylazulenes 7-12 in good yields. Redox behavior of the novel azulene derivatives with 2- and 3-thienyl-substituted 3-12 was examined by cyclic voltarnmetry and differential pulse voltammetry, which revealed amphoteric redox behavior.