Abstract--On the basis of degradation studies, jatamansone is shown to have the structure and stereochemistry depicted in formula I, representing a new fundamental type. ... THE isolation of a sesquiterpene ketone, jatamansone from ~ardu~~ac~y~ a~urn~~s~ was reported earlier .I On the basis of degradation studies reported in the present co~unication, jatamansone can unequivocally be assigned the structure and stereochemistry depicted in formula I. ...