Rhodium(II)-catalyzed decomposition of 3-O-(2-diazo-2-phenylacetyl)-1,2;5,6-di-O-isopropylidene-alpha-D-allofuranose: diastereoselective ether formation

Carbohydr Res. 2008 Jul 21;343(10-11):1819-23. doi: 10.1016/j.carres.2008.04.005. Epub 2008 Apr 7.

Abstract

Standard diazo transfer to 3-O-(2-phenylacetyl)-1,2;5,6-di-O-isopropylidene-alpha-d-allofuranose (2), using p-acetamidobenzenesulfonyl azide (p-ABSA, 3) and DBU as base, provides the expected 3-O-(2-diazo-2-phenylacetyl)-1,2;5,6-di-O-isopropylidene-alpha-D-allofuranose (4) as an orange syrup in 49% isolated yield. Subsequent decomposition of 4 using Rh(2)(OAc)(4) yields ether 5 in a highly diastereoselective manner and in 58% isolated yield. The X-ray crystal structure of 5 proves that both newly produced stereocenters have the (S) configuration; the conformation of the ester group at O-3 of the furanose ring of 5 is used to discuss the possible cause of the observed stereoselectivity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Azo Compounds / chemistry*
  • Catalysis
  • Crystallography, X-Ray
  • Ethers / chemical synthesis*
  • Glycosides / chemistry*
  • Molecular Conformation
  • Rhodium / chemistry*
  • Stereoisomerism

Substances

  • 3-O-(2-diazo-2-phenylacetyl)-1,2-5,6-di-O-isopropylideneallofuranose
  • Azo Compounds
  • Ethers
  • Glycosides
  • Rhodium