Synthesis of derivatives of 4-acetamido-4-deoxy-D- and L-arabinose

Abstract

4-Acetamido-4-deoxy-D- and L-arabinose have been synthesized from methyl 4-azido-4-deoxy-D- and L-arabinopyranoside, respectively. In contrast to other 4-acetamido-4-deoxypentoses, the arabinose derivatives in aqueous solution at tautomeric equilibrium exist both in the pyranose and in the furanose forms. The presence of the furanose form (containing nitrogen as the hetero atom in the ring) has been demonstrated by paper chromatography and infrared and nuclear magnetic resonance (n.m.r.) spectroscopy. Acetolysis of methyl 4-amino-4-deoxy-α-D-arabinopyranoside hydrochloride and of the N-acetyl derivative gave 4-acetamido-4-deoxy-D-arabinofuranose tetraacetates whose anomeric configurations were assigned by n.m.r. spectroscopy. Treatment of the 4-acetamido-4-deoxy-D-arabinofuranose tetraacetates with a cation exchange resin in methanol solution and subsequent de-O-acetylation, gave the anomeric methyl 4-acetamido-4-deoxy-D-arabinofuranosides, whose n.m.r. spectra in D2O exhibited the phenomenon of hindered internal rotation.