Significant Substituent Effect on the Anomerization of Pyranosides: Mechanism of Anomerization and Synthesis of a 1,2‐cis Glucosamine Oligomer from the 1,2‐trans Anomer |
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| Authors: | Dr Shino Manabe Prof Hiroko Satoh Prof Jürg Hutter Dr Hans Peter Lüthi Dr Teodoro Laino Dr Yukishige Ito |
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| Affiliation: | 1. RIKEN, Synthetic Cellular Chemistry Laboratory, Hirosawa, Wako, Saitama 351‐0198 (Japan), Fax: (+81)?48‐462‐9430;2. National Institute of Informatics (NII), Hitotsubashi, Chiyoda‐ku, Tokyo 101‐8430 (Japan), Fax: (+81)?3‐4212‐2120;3. Institute of Physical Chemistry, University of Zurich, 8057 Zurich (Switzerland);4. Swiss Federal Institute of Technology (ETH), Laboratory of Physical Chemistry, 8093 Zurich (Switzerland);5. IBM Research Zurich, 8803 Rüschlikon (Switzerland) |
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| Abstract: | Aminoglycosides containing a 2,3‐trans carbamate group easily undergo anomerization from the 1,2‐trans glycoside to the 1,2‐cis isomer under mild acidic conditions. The N‐substituent of the carbamate has a significant effect on the anomerization reaction; in particular, an N‐acetyl group facilitated rapid and complete α‐anomerization. The differences in reactivity due to the various N‐substituents were supported by the results of DFT calculations; the orientation of the acetyl carbonyl group close to the anomeric position was found to contribute significantly to the directing of the anomerization reaction. By exploiting this reaction, oligoaminoglycosides with multiple 1,2‐cis glycosidic bonds were generated from 1,2‐trans glycosides in a one‐step process. |
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| Keywords: | carbohydrates cleavage reactions density functional calculations glycosides isomers |
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