Synthesis of O-beta-D-galactopyranosyl-(1 linked to 4)-O-(2acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 linked to 2)-D-mannose and its interaction with various lectins.

2-Methyl-[3,6-di-O-acetyl-2-deoxy-4-O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-alpha D-glucopyrano]-[2,1-d]-2oxazoline (4) was prepared from 2-acetamido-3,6-di-O-acetyl-2-deoxy-4-O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-alpha-D-glucopyranosyl chloride. Condensation of 3,4:5,6-di-O-isopropylidene-D-mannose dimethyl acetal with 4 in the presence of a catalytic amount of p-toluenesulfonic acid afforded O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-(1 linked to 4)-O-(2-acetamido-3,6-di-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-(1 linked to 2)-3,4:5,6-di-O-ispropylidene-D-mannose dimethyl acetal (6) in 8.6% yield. Catalytic deacetylation of 6 with sodium methoxide, followed by hydrolysis with dilute sulfuric acid, gave O-beta-D-galactopyranosyl-(1 linked to 4)-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 linked to 2)-D-mannose (7). The inhibitory activities of 7 and related sugars against the henagglutinating activities of various lectins were assayed, and 7 was found to be a good inhibitor against Phaseolus vulgaris hemagglutinin.