Abstract
ABSTRACT A total synthesis of the β-methyl glycoside of lacto-N-fucopentaose III (1) is described. Phenyl 2,3,4,6-tetra-O-benzoyl-β-D-galactopyranosyl-(1→4)-6-O-benzyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (4), a key intermediate prepared by condensation of 2,3,4,6-tetra-O-benzoyl-α-D-galactopyranosyl bromide (2) and phenyl 6-O-benzyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (3), was glycosylated with ethyl 2,3,4-tri-O-benzyl-1-thio-β-L-fucopyranoside (5) to give the trisaccharide donor 6, which, on coupling with methyl 2,6-di-O-benzyl-β-D-galactopyranosyl-(1→4) 2,3,6-tri-O-benzyl-β-D-glucopyranoside (7), afforded the pentasaccharide 8. It was easily transformed into the target pentasaccharide 1 via hydrazinolysis, acetylation, O-deacetylation, and hydrogenolysis.
Published Version
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