Synthesis and Redox Behavior of 1,3‐Bismethylthio‐) 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

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 Tf 2 O, followed by treatment with triethylamine 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 voltammetry and differential pulse voltammetry, which revealed amphoteric redox behavior. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)