Synthesis of ferrocene amides and esters from aminoferrocene and 2-substituted ferrocenecarboxylic acid and properties thereof

Abstract

Different ferrocenecarboxamides were synthesized from aminoferrocene and various acid coupling partners such as N_α-Boc-L-tryptophan and N-protected sugar amino acids (N-Boc-3-amino-3-deoxy-1,2-O-isopropylidene-α-D-ribofuranoic acid, N-Boc-3-amino-3-deoxy-1,2-O-isopropylidene-α-D-xylofuranoic acid and their corresponding homo- and hetero-dimers). Similarly, reactions between 2-aminoethyl ferrocenecarboxylate and N-protected sugar amino acids afforded compounds with a carboxamide functional group remotely positioned from the ferrocene core. The X-ray diffraction structure of one of them showed the presence of an intermolecular hydrogen bond between the amide functional groups. Carbonylamino (or carbonyloxy) and oxycarbonyl 1,2-disubstituted ferrocenes were prepared either as racemic mixtures or in enantiomerically pure (S_P) form. Their electrochemical evaluation revealed distinctive features. Interestingly, the enantiomerically pure ferrocene diester showed a large potential shift (+45 mV) in the presence of L-glutamic acid. Finally, some of the synthesized ferrocenes were evaluated for their antibacterial, antifungal and antiproliferative (MCF-7) activities.