Studies on Sialic Acids. XXV. Synthesis of the α- and β-N-Glycosides of 3-Deoxy-D-glycero-D-galacto-2-nonulosonic Acid (KDN)

Several α- and β-N-glycosides of 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (1, KDN) were synthesized under Vorbruggen and Williamson reaction conditions. Two hexa-O-acetyl derivatives of 1 were treated with trimethylsilyl deriatives of pyrimidine, 5-fluoropyrimidine and 5-methylpyrimidine, and azidotrimethylsilane so give mixtures of α- and -β-N-glycoside derivatives of 1. Two penta-O-acetyl-2-chloro derivatives of 1 were treated with the sodium salts of 2, 4(1H, 3H)-pyrimidinedione, 5-fluoro-2, 4(1H, 3H)-pyrimidinedione and 5-methyl-2, 4(1H, 3H)-pyimidinedione to give only the α-N-glycosides. THe anomeric configurations of these compounds could be elucidated on the basis of the coupling pattern of C-1 in 13C-nuclear magnetic resonance spectral analysis.