Isopropyl 6‐amino‐2,5‐anhydro‐6‐ N ‐(2,5‐anhydro‐6‐azido‐3,6‐dideoxy‐ l ‐ lyxo ‐hexonyl)‐3,6‐dideoxy‐ l ‐ lyxo ‐hexonate 2.5‐hydrate

The title compound, C 15 H 24 N 4 O 7 ·2.5H 2 O, was crystallized with great difficulty from an aqueous solution after several months at 278 K. The crystal structure contains two independent molecules in the asymmetric unit, together with five molecules of water. The independent molecules, which have a very similar geometry, are related by a non‐crystallographic pseudo‐twofold rotation axis approximately perpendicular to the bc plane. Some intramolecular hydrogen bonds are present in both of the independent molecules. Moreover, the water molecules play a key role in the formation of a hydrogen‐bond network.