Helically Chiral Ferrocene Peptides Containing 1′-Aminoferrocene-1-Carboxylic Acid Subunits as Turn Inducers (pages 4965–4980)
Lidija Barišić, Mojca Čakić, Khaled A. Mahmoud, You-nian Liu, Heinz-Bernhard Kraatz, Hans Pritzkow, Srećko I. Kirin, Nils Metzler-Nolte and Vladimir Rapić
Article first published online: 24 MAY 2006 | DOI: 10.1002/chem.200600156
Turning point: Ferrocene amino acid (Fca) was incorporated into peptides with D- and L-alanine residues on the carboxy or amino group, or both. The helical chirality of ferrocene depends on the chirality of the amino acid at the N terminus of Fca (CD spectra, center). The degree of substitution of both Cp rings determines the H-bonding patterns. In dipeptides with one intramolecular H-bond (1), H-bonded and open forms are in equilibrium. Higher peptides, such as tetrapeptide 2, form two intramolecular H-bonds stabilizing a single conformation.