Synthesis of the pentasaccharide repeating unit of latosillan

A pentasaccharide, β-d-Man-(1→2)-[β-d-GlcNAc-(1→4)]-α-l-Rha-(1→4)-α-l-Rha-(1→4)-α-l-Rha-1-OC8H17, representing the repeating unit of latosillan, was convergently synthesized from the building blocks, ethyl 2,3-O-isopropylidene-1-thio-α-l-rhamnopyranoside, 2-O-acetyl-3,4,6-tri-O-benzyl-β-d-glucopyranosyl trichloroacetimidate, and 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl trichloroacetimidate under standard glycosylation conditions. The target pentasaccharide showed acceptable differentiation-inducing activity on HL-60 cell lines at the dosages of 10–50 μg/mL.

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