Structure of (+)-kjellmanianone, a highly oxygenated cyclopentenone from the marin alga, Sargassum kjellmanianum.
The structure and absolute configuration of a new cyclopentenone derivative, (+)-kjellmanianone, isolated from the brown alga Sargassum kjellmanianum has been determined as 5-carbomethoxy-5-hydroxy-3-methoxy-2-cyclopenten-1-one on the basis of the chemical and spectroscopic evidence and the X-ray analysis.