2-アセトアミド-2-デオキシグリコシルホスファイトを糖供与体とする直接的グリコシル化反応

抄録

A direct method for the construction of 2-acetamido-2-deoxy-β-D-glycosidic linkages has been developed. The 3,4,6-tri-O-benzyl- or 3,4,6-tri-O-acetyl-protected 2-acetamido-2-deoxy-α-D-glucosyl and galactosyl diethyl phosphites each reacted with a range of acceptor alcohols in the presence of a stoichiometric amount of bis(trifluoromethanesulfon)imide in CH₂Cl₂ at –78 °C to afford 1,2-trans-β-linked disaccharides in good to high yields. It is worthy of note that the alcohols bearing acid-sensitive acetal or epoxy groups were safely glycosylated under these conditions. Mechanistic investigations suggest that this protocol represents the first successful example of the direct glycosidation using 2-acetamido-2-deoxyglycosyl donors that does not proceed via an oxazolinium ion intermediate. A plausible reaction mechanism is proposed.

Scheme 1