Mechanistic studies on the stereoselective formation of glycosyl iodides: First characterization of β-D-glycosyliodides

Jacquelyn Gervay-Hague, Truc N. Nguyen, Michael J. Hadd

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Abstract

Treatment of glycosyl acetates with one equivalent of iodotrimethylsilane at low temperature results in the quantitative formation of glycosyl iodides. Carbohydrates that possess a participating group at the C-2 position initially form β-D-glycosyl iodides, which quickly equilibrate to the α-iodo anomers. The β anomer of peracetylated glucose reacts faster than the α anomer, presumably because the C-2 acetate can assist in displacing the silylated anomeric acetate. In contrast, the α anomer reacts faster than the β anomer in substrates lacking a participating group at C-2. For example, activation of 1-O-acetyl-2,3,4,6-tetra-O-benzyl-α-D-glucopyranose leads to formation of the β iodide, while the corresponding β acetate produces the α iodide. Although the β iodides quickly equilibrate to the α anomers, they can be prepared in sizable quantities at low temperatures where equilibration is slow. This report describes the first stereoselective formation and characterization of β-D-glycosyl iodides.

Original languageEnglish (US)
Pages (from-to)119-125
Number of pages7
JournalCarbohydrate Research
Volume300
Issue number2
DOIs
StatePublished - May 12 1997
Externally publishedYes

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Keywords

  • β-D-Glycosyl iodides
  • Glycosyl iodides
  • NMR characterization

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Organic Chemistry

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