(1R,4R,5aS,7S,9aS)-7,9a-Dimethyl-6-methyl-ene-3-oxo-1,3,4,5,5a,6,7,8,9,9a-deca-hydro-naphtho-[1,2-c]furan-1,4-diyl diacetate.

The title compound, C(19)H(24)O(6), is a sesquiterpene lactone isolated from the Kenyan plant Warburgia ugandensis. Ring A adopts a chair conformation, ring B is in a C(2) twist conformation and the lactone ring is nearly planar with maximum deviation 0.007 (1) Å. The reported absolute configuration is based on that of the similar compound bromo-parasiticolide A and is supported by analysis of Bijvoet differences from light atoms in Mo Kα radiation.