Synthesis and characterization of novel N-para-ferrocenyl benzoyl dipeptide esters

N-para-ferrocenyl benzoyl dipeptide esters 2–5 were prepared by coupling para-ferrocenyl benzoic acid 1 to the dipeptide ethyl esters GlyGly(OEt) 2, GlyAla(OEt) 3, GlyLeu(OEt) 4 and GlyPhe(OEt) 5. The compounds were fully characterized by a range of NMR spectroscopic techniques, mass spectrometry (ESI-MS, FABMS, MS/MS) and cyclic voltammetry (CV). The a1 and b1 ions appeared at one mass unit less than the expected mass in the tandem mass spectra. The CV curves of compounds 2–5 exhibited quasi-reversible redox behavior similar to the Fc/Fc+ redox couple and displayed oxidation potential values in the 50–55 mV range, against the Fc/Fc+ redox couple.