RESUMO
Precise NMR structural determination of distinct hydrogen-bonded secondary folds in unnatural peptides is demonstrated by using residual dipolar couplings (RDCs), measured in organic solvent media. The results show that the conventional constraints, (3)J(HH) and NOE-derived distances alone do not allow the accurate structural elucidation even for rigid foldamers and emphasize the need of RDC-based structure validation and refinement for unnatural peptides in particular and small organic molecules in general.
Assuntos
Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética/métodos , Compostos Orgânicos/química , Solventes/química , Estrutura MolecularRESUMO
The oligomers of constrained cis-exo-beta-norbornene amino acid were synthesised and characterised by extensive NMR, CD, IR and MD studies. The results showed the formation of both right and left handed consecutive 6-membered hydrogen-bonded strands for [2S,3R] and [2R,3S] enantiomers, respectively.
Assuntos
Aminoácidos/química , Biomimética , Norbornanos/química , Oligopeptídeos/química , Ligação de Hidrogênio , Oligopeptídeos/síntese química , Estrutura Secundária de Proteína , Análise Espectral , EstereoisomerismoRESUMO
The divergent and enantioselective total synthesis of the powerful antifungal marine natural product bengazole A has been achieved.