A commercially available 0.1 M solution of HClO(4) in dioxane has been shown to catalyze the glycosidation of glycosyl diphenyl phosphates. The per-O-benzyl-protected glucosyl and galactosyl donors and the 3,4,6-tri-O-acetyl-2-azido-2-deoxygalactosyl donor each react with a range of acceptor alcohols in the presence of 0.05-0.2 equiv of HClO(4) in dioxane/Et(2)O (1:1) to afford glycosides in good yields with good to excellent alpha selectivities. The synthetic utility of this glycosidation method was demonstrated by a stereoselective synthesis of the alpha-galactosylceramide KRN7000, an activator of natural killer (NK) T cells through CD1d molecules.

Leave this area blank for abstract info. Abstract-A direct and practical method for the construction of β-mannosidic linkages is described. While β-selectivities in the TMSOTfpromoted glycosidation of 2,3,4,6-tetra-O-benzyl-D-mannosyl diethyl phosphite are found to be highly dependent on the reactivity of acceptor alcohols, 2,3-di-O-benzyl-4,6-O-benzylidene-D-mannosyl diethyl phosphite reacts with a wide range of acceptor alcohols in the presence of TMSOTf in CH 2 Cl 2 at -45 °C to give β-mannosides in high yields with good to high β-selectivities.

Leave this area blank for abstract info. Abstract-A direct and practical method for the construction of β-mannosidic linkages is described. While β-selectivities in the TMSOTfpromoted glycosidation of 2,3,4,6-tetra-O-benzyl-D-mannosyl diethyl phosphite are found to be highly dependent on the reactivity of acceptor alcohols, 2,3-di-O-benzyl-4,6-O-benzylidene-D-mannosyl diethyl phosphite reacts with a wide range of acceptor alcohols in the presence of TMSOTf in CH 2 Cl 2 at -45 °C to give β-mannosides in high yields with good to high β-selectivities.

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