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NMR study of methyl 3,4,6‐tri‐ O ‐acetyl‐2‐deoxy‐2‐(alkylureido)‐β‐ D ‐glucopyranosides
Author(s) -
Wawer Iwona,
Weychert Małgorzata,
Klimkiewicz Jan,
PiekarskaBartoszewicz Bogusława,
Temeriusz Andrzej
Publication year - 1999
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/(sici)1097-458x(199903)37:3<189::aid-mrc432>3.0.co;2-b
Subject(s) - chemistry , substituent , chemical shift , carbon 13 nmr , steric effects , stereochemistry , nuclear magnetic resonance spectroscopy , ring (chemistry) , proton nmr , organic chemistry
Five derivatives of methyl3,4,6‐triacetyl‐2‐deoxy‐(3′‐dialkylureido)‐β‐ D ‐glucopyranoside were studied by 1 H and 13 C, NMR spectroscopy in CDCl 3 solutions and by 13 C NMR spectroscopy in the solid state. Sterically crowded substituents such as n ‐hexyl and cylcohexyl change the chemical shifts of H‐1, H‐2 and H‐3 and also the chemical shifts of C‐2 and C‐3 of the glucopyranose ring. The low‐temperature 1 H and 13 C spectra showed separate signals of the two alkyl groups, located E and Z with respect to C‐2′O. The barrier to rotation of the N‐3′—R 2 fragment (Δ G ) is 40.4 kJ mol −1 for the diethyl and 39.2 kJ mol −1 for the di‐ n ‐hexyl substituent. The solid‐state 13 C NMR spectra indicated that both of the above compounds are polymorphic, exhibiting two to four different forms. Copyright © 1999 John Wiley & Sons. Ltd.