Synthesis and glycosylation of a series of 6-mono-, di-, and trifluoro S-phenyl 2,3,4-tri-O-benzyl-thiorhamnopyranosides. Effect of the fluorine substituents on glycosylation stereoselectivity

J Am Chem Soc. 2007 Sep 26;129(38):11756-65. doi: 10.1021/ja0730258. Epub 2007 Aug 29.

Abstract

A series of 6-mono-, di-, and trifluoro analogs of S-phenyl 2,3,4-tri-O-benzyl-D- or L-thiorhamnopyranoside has been synthesized and used as donors in glycosylation reactions, with activation by the 1-benzenesulfinyl piperidine/triflic anhydride system. The stereochemical outcome of the glycosylation reactions was found to depend on the electron-withdrawing capability of the disarming substituent at the 6-position, i.e., on the number of fluorine atoms present. The results are explained with regard to the increased stability of the glycosyl triflates, shown to be intermediates in the reaction by low-temperature 1H NMR experiments, with increased fluorine content.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Benzylidene Compounds / chemistry*
  • Carbohydrate Conformation
  • Carbohydrate Sequence
  • Fluorine / chemistry*
  • Furans / chemistry*
  • Glycosylation
  • Magnetic Resonance Spectroscopy
  • Models, Chemical
  • Molecular Sequence Data
  • Piperidines / chemistry*
  • Rhamnose / analogs & derivatives
  • Rhamnose / chemical synthesis*
  • Stereoisomerism
  • Sulfonamides / chemistry*
  • Thioglycosides / chemical synthesis*

Substances

  • Benzylidene Compounds
  • Furans
  • Piperidines
  • Sulfonamides
  • Thioglycosides
  • Fluorine
  • piperidine
  • triflic anhydride
  • Rhamnose