Synthesis of β-d-Glcp-(1→3)-[β-d-Glcp-(1→6)]-β-d-Glcp-(1→3)-β-d-Glcp-(1→6)-[β-d-Galp-(1→4)-β-d-Glcp-(1→3)]-β-d-GlcpOLauryl, an oligosaccharide with anti-tumor activity

A concise and effective synthesis of lauryl heptasaccharide 17 was achieved from the key intermediates lauryl 2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl-(1→4)-2,3,6-tri-O-benzoyl-β-d-glucopyranosyl-(1→3)-2,4-di-O-benzoyl-β-d-glucopyranoside (10) and isopropyl 2,4,6-tri-O-acetyl-3-O-allyl-β-d-glucopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→6)]-2,4-di-O-acetyl-β-d-glucopyranosyl-(1→3)-2,4,6-tri-O-acetyl-1-thio-β-d-glucopyranoside (15). The key trisaccharide glycosyl acceptor 10 was constructed by coupling 2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl-(1→4)-2,3,6-tri-O-benzoyl-α-d-glucopyranosyl trichloroacetimidate (3) with lauryl 6-O-acetyl-2,4-di-O-benzoyl-β-d-glucopyranoside (9), followed by deacetylation. The thioglycoside donor 15 was obtained by condensation of 2,4,6-tri-O-acetyl-3-O-allyl-β-d-glucopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→6)]-2,4-di-O-acetyl-α-d-glucopyranosyl trichloroacetimidate (11) with isopropyl 4,6-O-benzylidene-1-thio-β-d-glucopyranoside (12), followed by debenzylidenation and acetylation. A bioassay of the inhibition of S180 noumenal tumors showed that lauryl heptasaccharide 17 could be employed as a potential agent for cancer treatment.

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