Evidence for endocyclic cleavage of conformationally restricted glycopyranosides.
2,3-trans-Carbamate- and -carbonate-carrying pyranosides were very easily anomerised from the beta to the alpha direction in the presence of a Lewis acid compared to other pyranosides. This reaction is caused by endocyclic cleavage of the pyranosides. Evidence for endocyclic cleavage of conformationally restricted pyranosides in the chair form was obtained by intra- and intermolecular Friedel-Crafts reactions, chloride addition, and reduction of the generated cation. On the other hand, pyranosides with the distorted conformation were never cleaved in an endocyclic manner.
Manabe
Shino
S
RIKEN Advanced Science Institute, Wako, Hirosawa, Saitama 351-0198, Japan. smanabe@riken.jp
Ishii
Kazuyuki
K
Hashizume
Daisuke
D
Koshino
Hiroyuki
H
Ito
Yukishige
Y
D002412:Cations / Q000737:chemistry; D018360:Crystallography, X-Ray; D006027:Glycosides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D013237:Stereoisomerism
D002412:Cations; D006027:Glycosides