The structure proposed previously for this unexpected oxidation product of
cr-santonin was verified by X-ray diffraction to be [3S-(3a,3a alpha,5a bet
a,9a alpha,9b beta)]-9a-acetyl-3a,4,5,5a,9a,9b-hexahydro-3,5a-dimethyl-2H-f
uro[3,2-h]- [1]benzopyran-2,8(3H)-dione, C15H18O5.