4-Oxo-D-arabino-3-azaoctano-1,5-lactone 1, synthesized by an unambiguo
us route, decomposes in neutral aqueous media to the corresponding ope
n-chain acid 5 which shows no activity against viral neuraminidase und
er conditions where N-acetyl-2,3-dehydro-2-deoxyneuraminic acid 2 prov
es active.