(8R,14S)-8-angeloyloxythapsan-14-ol,a sesquiterpene with a novel carbon skeleton,from Thapsia villosa

The roots of Thapsia villosa afforded in addition to other terpenoids, a sesquiterpene, with a new carbon skeleton. The structure, including the relative configuration, was elucidated by spectroscopic methods, a few chemical transformations and by X-ray analysis. The absolute configuration was determined by means of the method of Horeau. The trivial name thapsan is suggested for the parent structure [2aR,2bR,6aS,7aS]-2b,3,3,6a-tetramethylperhydroindeno[2,3-c]-furan.