9-[(E)-2-(4-Chloro-phen-yl)ethen-yl]-3,3,6,6-tetra-methyl-2,3,4,5,6,7,8,9-octa-hydro-1H-xanthene-1,8-dione.

In the title compound, C25H27ClO3, each of the cyclo-hexenone rings adopts an envelope conformation, whereas the six-membered pyran ring adopts a flattened boat conformation, with the O and methine C atoms deviating from the plane of the other four atoms. The C=C double bond is in the trans conformation. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into chains running parallel to the b axis.