The main conformer of symmetrical conjugates of ferrocene‐1,1′‐dicarboxylic acid with natural amino acids – Fn(CO–AA1–2–OMe)2 (type I, Fn = ferrocene‐1,1′‐diyl, AA = L‐α‐amino acid) – is supported by two hydrogen bonds between the peptide substituents. To compare intramolecular hydrogen bond patterns of type I conjugates with related asymmetrically substituted derivatives, type II (MeNHCO–Fn–CO–AA–OMe) and type III conjugates (MeNHCO–Fn–CO–AA–NHMe) were prepared in moderate‐to‐good yields in a few steps starting from 1′‐(methoxycarbonyl)ferrocene‐1‐carboxylic acid by using the HOBt/EDC method (AA = Gly, Ala, Val). 1H NMR spectroscopic variation ratio analysis suggests that an increase in the steric demand of the amino acid side chains favours conformations with hydrogen‐bonded FnCONHMe groups. CD spectroscopy of chiral derivatives reveals that (P)‐helical conformations predominate in solution. The experimental findings are in accordance with DFT calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Ferrocene ureidopeptides 3 and 4 and their derivatives 7 and 8 with a methyl ester substituent in 1′ position of the ferrocene have been prepared starting from ferrocenecarboxazide (1) or methyl 1′-azidocarbonylferrocene-1-carboxylate (5) via the corresponding isocyanatoferrocenes (2/6) and their coupling with alanine and alanylalanine methyl esters. Thorough spectroscopic and theoretical analyses revealed that in systems 4, 7, and 8 intramolecular hydrogen bonds play only a minor role, while selfassembly processes prevail in solution and in the solid state with urea NH groups acting as hydrogen donors and alanine amide and alanine ester CO groups acting as hydrogen acceptors. The ester substituent in the 1′ position of the ferrocene in compounds 7 and 8 does not engage in hydrogen bonding.

Novel O-alkylated quinoline and N-alkylated 4-quinolone derivatives attached to the ferrocene moiety through 4,1-(7a-d, 8a-d and 12a-d) and 1,4-disubstituted (9a, 9b, 10a and 10b) 1,2,3-triazole moiety were synthesized. The observed regioselectivity of O-vs. N-alkylation was explored by the use of NMR and computational techniques. Among the N-alkylated derivatives, the quinolone-ferrocene conjugate 9a displayed marked activities against chronic myeloid leukemia in blast crisis (K562) and Burkitt lymphoma (Raji). The 6-chloroquinolone-ferrocene conjugate 12c, with selective inhibitory activity on Raji cells and no cytostatic effect on normal MDCK1 cells was highlighted as the most promising anticancer organometallic complex in a group of O-alkylated quinolines.

The extension of peptide derivatives of ferrocene-1,1Ј-dicarboxylic acid by formal insertion of NH units between ferrocene and peptide strands results in ferrocene-bis(ureido)-peptides. Experimentally, alanine and dialanine methyl esters were attached to the 1-and 1Ј-position of 1,1Ј-diisocyanoferrocene to give the corresponding bis(ureido)peptide derivatives 3 and 4. The conformation of 3 has been deter-