Evidence for Endocyclic Cleavage of Conformationally Restricted Glycopyranosides |
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| Authors: | Shino Manabe Dr. Kazuyuki Ishii Dr. Daisuke Hashizume Dr. Hiroyuki Koshino Dr. Yukishige Ito Dr. |
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| Affiliation: | 1. RIKEN Advanced Science Institute, Wako, Hirosawa, Saitama 351‐0198 (Japan), Fax: (+81)?48‐462‐4680;2. PRESTO (Japan) Science and Technology Agency, Honcho, Kawaguchi, Saitama, 332‐0012 (Japan);3. Advanced Technology Support Division, RIKEN Advanced Science Institute, Wako, Hirosawa, Saitama 351‐0198 (Japan) |
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| Abstract: | 2,3‐trans‐carbamate‐ and ‐carbonate‐carrying pyranosides were very easily anomerised from the β to the α 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. |
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| Keywords: | carbohydrates cations cleavage reactions Friedel– Crafts reaction reduction |
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