2,4,6-Trimethylpyridine → Methyl 6-O-(4-O-acetyl-2,3,6-tri-O-benzyl-alpha-D-galactopyranosyl)-2,3,4-tri-O-benzyl-alpha-D-glucopyranoside

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Ethereal silver perchlorate (0.08 M, 76.9 mL, 6.15 mmol) is added with stirring at -30° C. to a solution of methyl 2,3,4-tri-O-benzyl-α-D-glucopyranoside (2.078 g, 4.48 mmol), 4-O-acetyl-2,3,6-tri-O-benzyl-α-D-galactopyranosyl chloride (2.859 g, 5.6 mmol) and 2,4,6-trimethylpyridine (0.81 mL, 6.15 mmol) in ether (20 mL). The mixture is stirred 15 min at -30° C. and silver chloride precipitated. The mixture is filtered through a celite pad, the solids are washed with ether, the filtrate is concentrated under reduced pressure. The residue is dissolved in methylene chloride and the organic layer is washed successively with aqueous sodium thiosulfate and water. The organic layer is dried over sodium sulfate, filtered and concentrated under reduced pressure so as to afford a foam. Flash chromatography on silica gel and elution with a graded mixture of hexane and ethyl acetate will afford methyl 6-O-(4-O-acetyl-2,3,6-tri-O-benzyl-α-D-galactopyranosyl)-2,3,4-tri-O-benzyl-α-D-glucopyranoside as a foam.

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