9α-Hy-droxy-12-{[4-(4-meth-oxy-phen-yl)piperazin-1-yl]meth-yl}-4,8-dimethyl-3,14-dioxatricyclo-[9.3.0.0]tetra-dec-7-en-13-one.

The title compound, C(26)H(36)N(2)O(5), was synthesized from 9α-hy-droxy-parthenolide (9α-hy-droxy-4,8-dimethyl-12-methyl-ene-3,14-dioxatricyclo-[9.3.0.0(2,4)]tetra-dec-7-en-13-one), wich was isolated from the chloro-form extract of the aerial parts of Anvillea radiata. The mol-ecule is built up from fused five- and ten-membered rings with the meth-oxy-phenyl-piperazine group as a substituent. The ten-membered ring adopts an approximate chair-chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring a flattened envelope conformation; the C(H)-C-C(H) atoms representing the flap lie out of the mean plane through the remaining four atoms by 0.343 (3) Å. The dihedral angle between the mean planes of the ten-membered ring and the lactone ring is 18.12 (14)°. An intra-molecular O-H⋯N hydrogen bond occurs. The crystal structure features weak C-H⋯O inter-actions.