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Analysis of the 1 H and 13 C NMR spectra of the novel macrolide antibiotic roxithromycin. Structure and conformation in solution
Author(s) -
GharbiBenarous Josyane,
Delaforge Marcel,
Artaud Isabelle,
Girault JeanPierre
Publication year - 1990
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260281003
Subject(s) - roxithromycin , chemistry , intramolecular force , hydrogen bond , crystallography , nmr spectra database , nuclear magnetic resonance spectroscopy , stereochemistry , carbon 13 nmr , molecule , methanol , proton nmr , spectral line , organic chemistry , antibiotics , physics , biochemistry , erythromycin , astronomy
A complete assignment of the 1 H and 13 C NMR spectra of roxithromycin in deuteriochloroform, methanol‐ d 4 and D 2 O was made using different two‐dimensional (2D) chemical shift correlation methods. The coupling constants observed by 1 H NMR and the NOEs show that the predominant conformation of roxithromycin in CDCl 3 solution is very similar to that in the crystalline state. However, variable‐temperature and variable‐solvent NMR experiments show that the major conformation of roxithromycin presents a conformational flexibility in the C‐2–C‐8 region and, particularly, in the C‐4–C‐5 bond of the molecule. The NOE data indicate that the 9‐[ O ‐(2,5‐dioxahexyl)oxime] chain is directed towards the 6‐OH, certainly involving an intramolecular hydrogen bond. This results in a globular structure for roxithromycin with less freedom for the macrolactone ring and the sugar units.