Intramolecular hydrogen abstraction reaction promoted by N-radicals in carbohydrates. Synthesis of chiral 7-oxa-2-azabicyclo[2.2.1]heptane and 8-oxa-6-azabicyclo[3.2.1]octane ring systems

J Org Chem. 2003 Feb 7;68(3):1012-7. doi: 10.1021/jo026314h.

Abstract

The reaction of phenyl and benzyl amidophosphates and alkyl and benzyl carbamate derivatives of aminoalditols with (diacetoxyiodo)benzene or iodosylbenzene and iodine is a mild and selective procedure for the synthesis of chiral 7-oxa-2-azabicyclo[2.2.1]heptane and 8-oxa-6-azabicyclo[3.2.1]octane ring systems under neutral conditions. This reaction can be considered to be an intramolecular N-glycosidation that goes through an intramolecular 1,5-hydrogen abstraction promoted by an N-amido radical followed by oxidation of the transient C-radical intermediate to an oxycarbenium ion. This methodology proved to be useful not only as a suitable strategy for the preparation of these bicyclic arrays but also for the selective oxidation of specific carbons of the carbohydrate skeleton, constituting a good procedure for the synthesis of protected N,O-uloses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbohydrates / chemical synthesis
  • Carbohydrates / chemistry*
  • Heptanes / chemical synthesis*
  • Heptanes / chemistry
  • Hydrogen / chemistry
  • Indicators and Reagents
  • Models, Molecular
  • Molecular Structure
  • Octanes / chemical synthesis*
  • Octanes / chemistry
  • Oxidation-Reduction
  • Stereoisomerism

Substances

  • Carbohydrates
  • Heptanes
  • Indicators and Reagents
  • Octanes
  • Hydrogen