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Analysis of the 1H and 13C NMR spectra of the novel macrolide antibiotic roxithromycin. Structure and conformation in solution

✍ Scribed by Josyane Gharbi-Benarous; Marcel Delaforge; Isabelle Artaud; Jean-Pierre Girault

Publisher
John Wiley and Sons
Year
1990
Tongue
English
Weight
930 KB
Volume
28
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

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.

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