Ferrocene and benzene are regarded as analogous compounds due to their similarity in stability and aromatic reactivity. The homologation of benzene results in the formation of linearly-fused polycyclic aromatic hydrocarbons, commonly known as polyacenes. The polyacenes show good potentials as semiconducting materials for organic opto-electronic applications. Our research explores the possibility of extending π-conjugation of cyclopentadienyl rings of ferrocene with carbocyclic aromatic rings starting with ferrocene itself. We perform Friedel-Crafts acylation of ferrocene with succinic anhydride to give 1-(3-carboxypropionyl)ferrocene. Our attempts to perform direct ring-closing in the presence of trifluoroacetic anhydride (TFAA) results in formation of deep purple product whose full characterization is still underway. However, when we reduce the keto carbonyl to methylene in the presence of Zn(Cu), the resultant carboxylic acid undergoes facile ring-closing in the presence of TFAA to give α-keto-1,2-tetramethyleneferrocene. The previously reduced keto group is oxidized in the presence of MnO2 to give ferrocene-fused quinone. We are now focused on reductive aromatization of quinone by incorporating electron-withdrawing cyano (CN) groups on peri positions of ferrocenyl moiety. Synthesis and structural analysis of various products will be discussed.

Methodologies of extending π-conjugation in ferrocene

255th National Meeting (2018)

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