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

Org Biomol Chem. 2003 Nov 21;1(22):4039-46. doi: 10.1039/b307378e.

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-glycosylmethyl 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon / chemistry
  • Cyanides / chemistry*
  • Dioxanes / chemistry
  • Glycosides / chemistry*
  • Hot Temperature
  • Hydrazines / chemistry
  • Hydrocarbons
  • Hydrogen / chemistry
  • Methane / analogs & derivatives*
  • Methane / chemistry*
  • Models, Chemical
  • Models, Molecular
  • Nitrogen / chemistry
  • Sodium / chemistry

Substances

  • Cyanides
  • Dioxanes
  • Glycosides
  • Hydrazines
  • Hydrocarbons
  • carbene
  • Carbon
  • Hydrogen
  • Sodium
  • 1,4-dioxane
  • Nitrogen
  • Methane