organic compounds
The title compounds, dimethyl 2-methoxy-6-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl)amino-3,4- pyridinedicarboxylate, C21H26N2O12, (III), and dimethyl 2-methylthio-6-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl)amino-3,4-pyridinedicarboxylate, C21H26N2O11S, (IV), are isomorphous. Molecules are linked by N—HO hydrogen bonds [NO 2.891 (4) for (III) and 2.913 (5)Å for (IV)], which generate chains in the a direction.