Nepalensolide A, Novel Sesquiterpene Lactone from the Liverwort Frullania nepalensis. Compound Breaking the Samek Rule. A Study by NOE and X-Ray

Abstract
The structure of a new sesquiterpene lactone, nepalensolide A, from the liverwort Frullania nepalensis has been determined by spectroscopic considerations and X-ray analysis. Since the compound does not obey the Samek rule, the conformation has to be considered when we use this rule.