Synthesis and structure of some (E)-ferrocenemethylenecycloalkanones andtheir benzylidene analogues

Abstract

E-2-ferrocenemethylene- and E,E-diferrocenemethylenecycloalkanones as well as partial benzylidene analogues of the latter were synthesized by base-catalyzed Claisen-Schmidt condensation of ferrocenecarboxaldehyde with cyclopentanone, cyclohexanone, cycloheptanone and E-2-(4′-X-benzylidene) cycloalkanones. The stereostructure (configuration and conformation) and the electronic properties (conjugation of the enone moiety and the aromatic rings) of the compounds were studied by IR, 1H and 13C NMR methods. The spectroscopic properties of the ferrocene derivatives were compared with those of the respective benzylidene analogues.