Structure and Absolute Configuration of Kobusone and Isokobusone

Two norsesquiterpenoids, kobusone and isokobusone, have been newly isolated from nutgrass, Cyperus rotundus (Cyperaceae), and shown to have the stereostructures I and VII, respectively, by the spectral properties of them and their derivatives and by transformation of caryophyllene oxide (VI) to the oxido-ketone (I) which has further been converted into the keto-alcohol (VII).