The Synthesis of a Di-N-acetylchitobiose Asparagine Derivative, 2-Acetamido-4-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-1-N-(4-l-aspartyl)-2-deoxy-β-d-glucopyranosylamine

The crystalline glycosyl chloride obtained by treatment of α-chitobiose octaacetate with dry hydrogen chloride in acetyl chloride solution was treated with silver azide to give the crystalline β-1-azido derivative of peracetylated chitobiose. This compound was hydrogenated in the presence of platinum oxide into the crystalline β-1-amino derivative, which was condensed with 1-benzyl N-(benzyloxycarbonyl)-l-aspartate to give the crystalline benzyl ester, N-(benzyloxycarbonyl), penta-O-acetyl derivative of 2-acetamido-4-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-1-N-(4-l-aspartyl)-2-deoxy-β-d-glucopyranosylamine. The latter compound was obtained in crystalline form by catalytic hydrogenation in the presence of palladium on charcoal, followed by saponification of the resulting crystalline amino acid derivative with lithium hydroxide. It was characterized by its melting point and optical rotation, by thin layer chromatography, and by mass spectrometry of the per(trimethylsilyl) derivative.