C-Branched pyrrolidines from 2-C-acetylmethyl-glycosylazides. Reduction of imines formed by monosaccharide ring opening

Carbohydr Res. 2006 Oct 16;341(14):2434-8. doi: 10.1016/j.carres.2006.07.005. Epub 2006 Aug 1.

Abstract

Reduction of the protected 2-C-acetylmethyl-beta-glucopyranosyl azide derivative 1 produced the corresponding beta-glucosylamine 3. Rather than forming a conformationally strained 1,2-trans-fused bicyclic imine, we propose that the beta-glycosylamine underwent anomerization to an acyclic imine (4) followed by an intramolecular ring closure by the 5-hydroxy group. The resultant 2-C-acetylmethyl-alpha-glucopyranosylamine 5, which possesses the 1,2-cis-configuration was immediately converted to a bicyclic imine (2) in excellent yield. Attempts to selectively reduce the C=N double bond of 2 using sodium borohydride and cyanoborohydride failed to produce bicyclic amine 6. Instead, compound 6 underwent another ring-opening elimination and further reduction to produce a C-branched pyrrolidine (8) in good yield. Catalytic hydrogenation of 1 and 2 also provided the C-branched pyrrolidine (10).

MeSH terms

  • Azides / chemistry*
  • Carbohydrate Conformation
  • Cyclization
  • Imines / chemistry*
  • Magnetic Resonance Spectroscopy
  • Monosaccharides
  • Oxidation-Reduction
  • Pyrrolidines / chemical synthesis*
  • Pyrrolidines / chemistry
  • Stereoisomerism

Substances

  • Azides
  • Imines
  • Monosaccharides
  • Pyrrolidines
  • pyrrolidine