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Anomeric Effect of the Nitrogen Atom in the Isocyano and Urea Groups
Author(s) -
Ichikawa Yoshiyasu,
Watanabe Hitomi,
Kotsuki Hiyoshizo,
Nakano Keiji
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201000944
Subject(s) - chemistry , anomer , anomeric effect , pyranose , steric effects , nitrogen atom , urea , stereochemistry , nitrogen , crystallography , group (periodic table) , atom (system on chip) , organic chemistry , computer science , embedded system
The anomeric effect associated with the nitrogen atom in the isocyano group was investigated by using 1 H NMR spectroscopic analysis of an anomeric pair of xylopyranosyl isocyanides 8 and 7 . We found that β‐anomer 7 prefers to exist in the 1 C 4 conformation in which the nitrogen atom in the isocyano group adopts an axial orientation. This observation, coupled with the results of X‐ray crystallographic analysis establishes that the nitrogen atom in the isocyano group displays the anomeric effect. Furthermore, xylopyranosyl isocyanides 8 and 7 were transformed into the corresponding xylopyranosyl ureas 10 and 11 . In the case of the urea group, a normal sterically determined preference is observed in which the bulky urea substituents at the pyranose anomeric position occupy the equatorial position.