The synthesis and structural characterization of N-para-ferrocenyl benzoyl dipeptide esters: The X-ray crystal structure of N-{para-(ferrocenyl)benzoyl}-l-alanine-glycine ethyl ester

A series ofN-para-ferrocenyl benzoyl dipeptide esters 2–5 were prepared by coupling para-ferrocenyl benzoic acid (1) to the dipeptide ethyl esters using the conventional 1,3-dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBt) protocol. The dipeptides employed in the synthesis were Ala-Gly(OEt) (2), Ala-Ala(OEt) (3), Ala-Leu(OEt) (4) and Ala-Phe(OEt) (5). The compounds were fully characterized by a range of NMR spectroscopic techniques, electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). In addition the X-ray crystal structure of the l-alanine-glycine derivative 2 has been determined.