SYNTHETIC STUDIES ON CELL-SURFACE GLYCANS .70. A REGIO-CONTROLLED AND STEREO-CONTROLLED SYNTHESIS OF BETA-D-GLCP NAC6SO3-(1-]3)-BETA-D-GALP6SO3-(1-]4)-BETA-D-GLCPNAC6SO3-(1-]3)-D-GALP, A LINEAR ACIDIC GLYCAN FRAGMENT OF KERATAN SULFATE-I

A stereocontrolled synthesis of β-d-GlcpNAc6SO3-(1→3)-β-d-Galp6SO3-(1→4)-β-d-GlcpNAc6SO3 -(1→3)-d-Galp, was achieved by use of benzyl O-(2-acetamido-3,4 di-O-benzyl-2-deoxy-6-O-p-methoxyphenyl- β-d-glucopyranosyl)-(1→3)-O-(2,4-di-O-tert-butyldiphenylsilyl-β-d-galactopyranosyl-(1→4) -O-(2-acetamido-3-O-benzyl-2-deoxy-6-O-p-methoxyphenyl-β-d-glucopyranosyl)-(1→3)-2,4,6-tri-O-benzyl- β-d-galactopyranoside as a key intermediate, which was in turn prepared by employing two glycosyl donors, 3,4-di-O-acetyl-2,4-di-O-benzyl-β-d-galactopyranosyl)-(1→4)-3-O-benzyl-2-deoxy-6-O-p- methoxyphenyl-2-phthalimido-β-d-glucopyranosyl trichloroacetimidate, and a glycosyl acceptor, benzyl 2,4,6-tri-O-benzyl-β-d-galactopyranoside. © 1990.