The synthesis of oligosaccharide- l-asparagine compounds. Part IV. 2-acetamido- N-( l-aspart-4-oyl)-2-deoxy-6- O-α- d-mannopyranosyl-β- d-glucopyranosylamine

Abstract

The title compound, used for the chemical and biochemical synthesis of glycopeptides and as a reference substance in the structure elucidation of glycoproteins, was synthesized via two different routes. In one of these syntheses, condensation of 2,3,4,6-tetra- O-acetyl-α- d-mannopyranosyl bromide ( 1) with 2-acetamido-3,4-di- O-acetyl-2-deoxy-β- d-glucopyranosyl azide, or with the 3- O-acetyl azide analog, followed by acetylation, gave 2-acetamido-3,4-di- O-acetyl-2-deoxy-6- O-(2,3,4,6-tetra- O-acetyl-α- d-mannopyranosyl)-β- d-glucopyranosyl azide ( 4) in 76 and 74% yields, respectively. Catalytic reduction of 4 with Adams' catalyst, and condensation of the resulting amine with 1-benzyl N-(benzyloxycarbonyl)- l-aspartate, gave the protected derivative 10 of the title compound in 67% yield. In the other synthesis, 10 was obtained in 66% yield by condensation of 1 with 2-acetamido-3,4-di- O-acetyl- N-[1-benzyl N-(benzyloxycarbonyl)- l-aspart-4-oyl]-2-deoxy-β- d-glucopyranosylamine. Removal of the protective O-acetyl, N-(benzyloxycarbonyl), and benzyl groups gave the title compound.