Induced helix of 2-(2-aminophenoxy)alkanoic acid oligomers as a δ-peptidomimetic foldamer
摘要:
Peptidomimetic foldamers were synthesized by oligomerizing derivatives of the delta-amino acid analogue, 2-(2-aminophenoxy)alkanoic acid. Single-crystal analysis of the tetramer reveals a 2(1)-helical secondary structure stabilized by hydrogen bonding and the coiled stacking of aromatic rings. The M-helicity of 2-aminoplienoxyacetic acid oligomers was induced by the incorporation of only a single chiral carbon of the N-terminal (R)-2-(2-nitrophenoxy)propionamide moiety. The solution state CD spectra demonstrated that the resulting helix induced a substantial Cotton effect. The secondary structure was further characterized by IR and NMR spectroscopy. (c) 2008 Elsevier Ltd. All rights reserved.
A cyclic trimer of (R)-2-(2-aminophenoxy)propanoic acid, a delta-amino acid analogue, was synthesized. Molecular mechanics calculations on the cyclic trimer predicted that a concave network of sequential hydrogen bonds forms a C(3)-symmetric bowl-shaped structure. Evidence for this conformation was found in the NMR spectra of the trimer in D-chloroform. Although the single-crystal structure of the cyclic trimer indicates that chloroform could be included in the bowl-shaped structure, the conformation was not C(3)-symmetric and the hydrogen bonding network was of a different mode. These different conformations between solid and Solution were reasonably clear from IR spectra. (C) 2009 Elsevier Ltd. All Fights reserved.