O-Glycosidation reactions promoted by in situ generated silver N-heterocyclic carbenes in ionic liquids

Ian Jamie Talisman, Vineet Kumar, Jacqueline Razzaghy, Sanjay V. Malhotra

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

We herein report O-glycosidation reactions promoted via silver N-heterocyclic carbene complexes formed in situ in ionic liquids. Seven different room temperature ionic liquids were screened for the glycosidation reaction of 4-nitrophenol with tetra-O-acetyl-α-d-galactopyranosyl bromide. Good to excellent yields were obtained using Ag-NHC complexes derived from imidazolium halide salts to promote the glycosidation reaction, whereas yields considered moderate to low were obtained without use of the silver carbene complex. Anion metathesis of the ionic liquids with inexpensive alkylammonium halides also resulted in silver N-heterocyclic carbene formation and subsequent O-glycosidation in the presence of silver carbonate. Effective utility of this methodology has been demonstrated with biologically relevant acceptors (including flavones and steroids) where O-β-glycoside products were obtained selectively in moderate to good yields. We have also demonstrated that the Ag-NHC complex is a superior promoter to traditionally used silver carbonate for the glycosidation of polyphenolic acceptors. The ionic liquids used in the study could be recycled three times without apparent loss in activity.

Original languageEnglish (US)
Pages (from-to)883-890
Number of pages8
JournalCarbohydrate Research
Volume346
Issue number7
DOIs
StatePublished - May 15 2011
Externally publishedYes

Keywords

  • Ag-NHC complexes
  • Anion metathesis
  • Carbohydrates
  • Ionic liquids
  • O-Glycosidation

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

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