This molecule features a five-membered ring with four carbons and one oxygen, with a double bond between carbons 1 and 2. The ring oxygen is at position 5. At ring carbon 4, there are two substituents: (1) a hydroxyl group, and (2) an O-C(=O)-N=[N+]=[N-] unit (i.e., an oxygen bonded to a carbonyl that is further bonded to an azide, N=[N+]=[N-]). No other positions carry substituents or stereochemical designations.