SYNTHESIS OF DISACCHARIDE GLYCOSYL DONORS SUITABLE FOR INTRODUCTION OF THE BETA-D-GAL P-(1-]3)-ALPHA- AND -BETA-D-GAL PNAC GROUPS

摘要

2-(Trimethylsilyl)ethyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside (4) was glycosylated with phenyl 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-galactopyranoside to give 2-(trimethylsilyl)ethyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-galac topyranosyl)-beta-D-galactopyranoside (6) in 99% yield. Removal of the benzylidene group and acetylation gave the key intermediate 2-(trimethylsilyl)ethyl 4,6-di-O-acetyl-2-azido-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-galacto pyranosyl)-beta-D-galactopyranoside (7), which was transformed into methyl 4,6-di-O-acetyl-2-deoxy-2-phthalimido-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-g alactopyranosyl)-1-thio-beta-D-galactopyranoside (9) in two steps in an overall yield of 69%. Similarly, 7 was transformed in two steps into 4,6-di-O-acetyl-2-azido-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-galacto pyranosyl)-alpha-D-galactopyranosyl bromide (11) in an over-all yield of 86%. Compounds 9 and 11 are suitable glycosyl donors for introduction of the beta-D-Gal p-(1 --> 3)-beta- and -alpha-D-Gal pNAc groups. [References: 19]