4a-Hydroxy-9-(4-hydroxyphenyl)-4,4a,5,6,9,9a-hexahydro-3H-xanthene-1,8(2H,7H)-dione.

The title compound, C(19)H(20)O(5), was synthesized by the reaction of 1,3-cyclo-hexa-nedione and 4-hy-droxy-benzaldehyde in the presence of PdCl(2) and thio-urea. The tetra-hydro-pyran ring and the six-membered cyclo-hexene ring adopt envelope conformations, and the six-membered cyclo-hexane ring is in a chair conformation. The crystal packing is stabilized by classical inter-molecular O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions.