A Facile Synthesis of N-Acetylneuraminic Acid Glycal

Abstract

Treatment of the readily available peracetylated N-acetylneuraminic acid glycosyl chloride [methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-2-chloro-2,3,5-trideoxy-β-d-glycero-d-galactononulopyranosonate)] with anhydrous Na₂HPO₄ in refluxing MeCN quantitatively affords the peracetylated N-acetylneuraminic acid glycal [methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2,6-anhydro-d-glycero-d-galacto-non-2-enonate], which can be isolated from the reaction mixture by simple filtration and subsequent evaporation of the solvent. No glycal formation was detected at room temperature even after prolonged treatment with Na₂HPO₄. The method proposed is experimentally simple and allows ready preparation of substantial amounts of the title compound, which is an important intermediate in sialic acid chemistry.

Key words

carbohydrates - halides - eliminations - alkenes - phosphates

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10

Kononov, L. O., unpublished results.