Two ethyl 2-deoxy-alpha-D-hexo-3,7-pyranoso-3-octulosonate derivatives

In each of the two pyranoid sugars, ethyl 2-deoxy-4,5,6,8-tetra-O-acetyl-alpha-D-gluco-3,7-pyranoso-3-octulosonate, C18H26O12, and ethyl 2-deoxy-4,5,6,8-tetra-O-benzyl-alpha-D-galacto-3,7-pyranoso-3-octulosonate, C38H42O8, the anomeric configuration is alpha. The acetoxymethyl substituent on the hexopyranose ring of the former compound and the ethoxycarbonylmethyl substituents in both sugars all have the gauche-trans conformation, while the benzyloxymethyl substituent of the galactopyranose sugar has the trans-gauche conformation. In each structure, the anomeric hydroxy group forms an intramolecular hydrogen bond with the carbonyl O atom of the ethoxycarbonylmethyl substituent.