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Synthesis and Conformational Analysis of Methyl N ‐Alanyl‐1′‐aminoferrocene‐1‐carboxylate
Author(s) -
Barišić Lidija,
Kovačević Monika,
Mamić Marija,
Kodrin Ivan,
Mihalić Zlatko,
Rapić Vladimir
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201101270
Subject(s) - chemistry , stereochemistry , steric effects , carboxylate , ferrocene , hydrogen bond , conformational isomerism , amino acid , proton nmr , molecule , organic chemistry , biochemistry , electrode , electrochemistry
Structurally different ferrocene peptides I – VI exhibit considerable conformational differences. This study has explored the structural properties of VII [Y‐AA‐Fca‐OMe; Y = di‐ tert ‐butyl dicarbonate (Boc), acetyl (Ac); AA = L ‐Ala, D ‐Ala; Fca = 1′‐aminoferrocene‐1‐carboxylic acid] with an exchanged sequence of constituent amino acids relative to VI (Y‐Fca‐AA‐OMe; Y = Boc, Ac; AA = L ‐Ala, D ‐Ala). The ferrocene peptides VII were obtained by coupling C ‐protected Fca with Boc‐ L ‐Ala‐OH and Boc‐ D ‐Ala‐OH, respectively. The Boc protecting groups of the obtained conjugates Boc‐AA‐Fca‐OMe ( 2a , AA = L ‐Ala; 2b , AA = D ‐Ala) were converted to sterically less demanding Ac groups to give Ac‐AA‐Fca‐OMe ( 3a , AA = L ‐Ala; 3b , AA = D ‐Ala). In order to examine their conformational properties, peptides VII were subjected to spectroscopic analysis (IR, 1 H NMR, CD) and molecular modeling (DFT). The alteration of peptides VI into VII significantly influenced their conformational properties. Conjugates VI were stabilized through interchain hydrogen bonding, whereas inter‐ and intrachain hydrogen bonds were established in their constitutional isomers VII . The replacement of the bulky Boc group with an Ac group did not cause major conformational changes, and the absolute configuration of the alanine chiral centers did not affect the conformational properties.