N-(2-Carboxyethyl)-2,5-dideoxy-2,5-imino-d-mannonic acid [(3R,4R,5R)-1-(2-carboxyethyl)-3,4-dihydroxy-5-hydroxymethyl-l-proline]

The absolute stereochemistry of the title compound, C9H15NO7, was determined from the use of d-glucuronolactone as the starting material. The compound crystallizes as the zwitterion. The five-membered ring adopts an envelope conformation with the –CH2OH-substituted C atom forming the flap. An intramolecular N—H...O hydrogen-bond occurs. In the crystal, the compound exists as a three-dimensional O—H...O intermolecular hydrogen-bonded network with each molecule acting as a donor and acceptor for four hydrogen bonds.