Epiclusianone [3-benzoyl-4-hydroxy-6,6-dimethyl-1,5,7-tris(3-methyl-2-buten
yl)bicyclo[3.3.1]non-3-ene-2,9-dione] is a new isomeric form of the C33H42O
4 compound identified by X-ray diffraction analysis. Structure comparison w
ith the known clusianone evidences a case of epimerism in one of the chiral
C atoms. A comparison of the melting point and the optical activity of the
two isomers shows them to have different values.