Intramolecular hydrogen bonding in depsipeptides containing endo-3,6-tricyclo[6.2.1.0(2,7)]undeca-4,9-diene-3,6-endo-diol.
A variety of endo-3,6-tricyclo[6.2.1.0(2,7)]undeca-4,9-diene-3,6-endo-diol depsipeptide or bis-amino acid derivatives containing the same parallel strands were synthesised and examined for conformational preferences by NMR. The study indicates that this novel class of constrained peptides displays beta-turn-like and beta-sheet-like conformations. Evidences are supported by observation of the rates of proton-deuterium exchange, nuclear Overhauser effects and further by dynamic simulations, semi-empirical and ab initio calculations. The chemical shifts were measured in CDCl3 and CDCl3 with 15% DMSO-d6 solutions. It was carried out a van't Hoff analysis, which is in agreement with the theoretical studies. In chloroform-d, for the derivatives 3-6 the hydrogen-bonded species are enthalpically preferred but entropically disfavoured.
Instituto de Química, Universidade Federal do Rio Grande do Sul. CP 15003. Av. Bento Gonçalves, 9500 - Porto Alegre 91.501-970--RS-Brasil.
Mariane
M
Axt
Hassan
H
Oulyadi
Xavier
X
Pannecoucke
Jean-Charles
JC
Quirion
Adriana Raffin
AR
Pohlmann
Valentim Emilio Uberti
VE
Costa
D002855:Chromatography, Thin Layer; D047630:Depsipeptides / Q000737:chemistry*; D003903:Deuterium; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D006860:Hydrogen Bonding; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D012997:Solvents; D013055:Spectrophotometry, Infrared; D013696:Temperature; D013816:Thermodynamics
D047630:Depsipeptides; D006575:Heterocyclic Compounds, 3-Ring; D007202:Indicators and Reagents; D012997:Solvents; C508892:endo-3,6-tricyclo(6.2.1.0(2,7))undeca-4,9-diene-3,6-endo-diol; D003903:Deuterium