Abstract
Condensation of 1, 6 : 2, 3-dianhydro-β-D-mannopyranose with 2-methyl-(3, 4, 6-tri-O-acetyl-1, 2-dideoxy-α-D-glucopyrano)-[2', 1' : 4, 5]-2-oxazoline (2) in the presence of a catalytic amount of anhydrous p-toluenesulfonic acid in boiling 1, 2-dichloroethane afforded crystalline 4-O-(2-acetamido-3, 4, 6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-1, 6 : 2, 3-dianhydro-β-D-mannopyranose (3) in 42% yield. Azidolysis of the oxirane ring of 3, reduction of the azido to an amino group, and N-acetylation afforded 2-acetamido-4-O-(2-acetamido-3, 4, 6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-3-O-acetyl-1, 6-anhydro-2-deoxy-β-D-glucopyranose (6) in 50% yield. Compound 6 was indistinguishable from the product prepared in 52.2% yield by direct condensation of 2-acetamido-3-O-acetyl-1, 6-anhydro-2-deoxy-β-D-glucopyranose with 2. Acetolysis of 6 provided the title disaccharide.
