Condensation with 1, 2-O-ethylidene-4, 6-O-benzylidene-β- D-mannopyranose (2) as the acceptor and 2, 3, 4, 6-tetra-O-benzoyl- α-D-mannopyranosyl trichloroacetimidate (3) as the donor gave 3-O-linked disaccharide (4), subsequent debenzylidenation afforded the disaccharide acceptor5. Coupling of 5 with 3 selectively furnished 6-O-linked trisaccharide 6, then deethylidenation, acetylation, selective 1-O-deacetylation, and trichloroacetimidation yielded the trisaccharide donor 10. Condensation of 10 with 5 afforded 6-O-linked pentasaccharide 11, its deethylidenation followed by acetylation gave the required pentasaccharide 13. Coupling of 10 with 2 gave the tetrasaccharide 14, its debenzylidenation afforded the tetrasaccharide acceptor 15. Condensation of 15 with 3 gave the pentasaccharide isomer.

Key words: GLYCOPROTEIN, REGIOSELECTIVITY, STEREOSELECTIVITY, OLIGOSACCHARIDE, MANNOSE, ISOMER, SYNTHESIS