SYNTHESES OF THE METHYL GLYCOSIDES OF THE REPEATING UNITS OF CHONDROITIN 4-SULFATE AND 6-SULFATE

3,4,6-Tri-O-acetyl-d-galactal was transformed into methyl 6-O-acetyl-2-azido-4-O-benzyl-2-deoxy- β-d-galactopyranoside and its 4-O-acetyl-6-O-benzyl analogue, each of which was glycosylated with activated, O-acetylated derivatives of methyl d-glucopyranosyluronate. The resulting β-(1→3)-linked disaccharide derivatives were each reductively N-acetylated, hydrogenolysed, O-sulfated, and saponified to afford the disodium salts of methyl 2-acetamido-2-deoxy-3-O-(β-d-glucopyranosyluronic acid)-4-O-sulfo-β-d-galactopyranoside and the 6-O-sulfo analogue. d-Galactal was also transformed into activated derivatives of 2-azido-3,6-di-O-benzyl-2-deoxy-d-galactopyranose and their 3,4-di-O-benzyl analogues with various substituents at O-4 and O-6. These glycosyl donors were condensed with 6-O-protected derivatives of methyl 2,3-di-O-benzyl-β-d-glucopyranoside to give the β-(1→4)-linked disaccharide derivatives, which were selectively deprotected, then oxidised at C-6 of the gluco unit, reductively N-acetylated, selectively deprotected, O-sulfated at C-4 or C-6 of the galacto unit, and hydrogenolysed to give the disodium salts of methyl 4-O-(2-acetamido-2-deoxy-4-O-sulfo-β-d-galactopyranosyl)-β-d-glucopyranosiduronic acid and the 6-O-sulfo analogue. © 1990.