The molecule is a monocarboxylic acid anion that is the conjugate base of pentalenolactone E, obtained by deprotonation of the carboxy group; major species at pH 7.3. It is a conjugate base of a pentalenolactone E.
(4aR,6aS,9aR)-8,8-dimethyl-1-methylidene-2-oxo-4a,6a,7,9-tetrahydro-4H-pentaleno[1,6a-c]pyran-5-carboxylate