C-Glycosylmethylene carbenes: Synthesis of anhydro-aldose tosylhydrazones as precursors; generation and a new synthetic route to exo-glycals

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Abstract

Acylated anhydro-aldononitriles (glycosyl cyanides) were transformed into anhydro-aldose tosylhydrazones by Raney-nickel reduction in the presence of tosylhydrazine in a one-pot reaction. The configuration of the C=N double bond in these hydrazones was E as proven by 15N-1H coupling constants as well as X-ray crystallography. Thermolysis in refluxing 1,4-dioxane of the sodium salts of the tosylhydrazones obtained by sodium hydride (generally 10 eq.) resulted in the formation of anhydro-1-deoxy-ald-1-enitols (exo-glycals). "Dimeric" N-glycosyl-methyl anhydro-aldose tosylhydrazones could also be isolated when the use of less base caused incomplete deprotonation of the starting compounds. This two-step procedure constitutes a novel, reasonably short synthetic pathway to acylated exo-glycals from the readily available glycosyl cyanides.

Original languageEnglish
Pages (from-to)4039-4046
Number of pages8
JournalOrganic and Biomolecular Chemistry
Volume1
Issue number22
DOIs
Publication statusPublished - Nov 21 2003

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ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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