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An Unusual C-1C-2 Ring-Splitting of Pyranosides by a Retro-Aldol Reaction - a Route to New Chiral Building Blocks

✍ Scribed by Peseke, Klaus ;Aldinger, Stephan ;Reinke, Helmut

Publisher: John Wiley and Sons
Year: 2006
Tongue: English
Weight: 492 KB
Volume: 1996
Category: Article
ISSN: 0947-3440
DOI: 10.1002/jlac.199619960614

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✦ Synopsis

Abstract

The treatment of the α‐oxoketene dithioacetal sugar derivatives 2 and 7 with concentrated hydrochloric acid in THF leads to the open‐chain uloses 3 and 8. The reaction mechanism can be rationalized as a retro‐aldol reaction. This rationalization was supported by reacting 2 and 7 with DCl/D^2^O. Compound 3 was converted into the chiral pyrazoles 12 and 13. The branched‐chain ulose 2 forms the thiopyranosidulose 15 when treated with diluted aqueous sulfuric acid in THF. The mechanism of this reaction was investigated by ^13^C‐labelling of the starting compound 2.

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