12-{[4-(2-Fluoro-phen-yl)piperazin-1-yl]-meth-yl}-9α-hy-droxy-4,8-dimethyl-3,14-dioxatricyclo-[9.3.0.0]tetra-dec-7-en-13-one.

The title compound, C(25)H(33)FN(2)O(4), 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), which was isolated from the chloro-form extract of the aerial parts of Anvillea radiata. The asymmetric unit contains two independent mol-ecules. In each mol-ecule, the ten-membered ring displays an approximative chair-chair conformation. Each of the piperazine rings adopts a perfect chair conformation, while both lactone rings show an envelope conformation, one with the C atom bearing the piperazin-1-ylmethyl group as the flap, the other with the junction C atom not attached to the ring O atom as the flap. The dihedral angles between the least-squares planes through the ten- and five-membered rings in the two mol-ecules are similar [19.1†(3) and 16.2†(3)°]. An intra-molecular O-H⋯N hydrogen bond stabilizes the mol-ecular conformation. The crystal packing is stabilized by C-H⋯O hydrogen bonds.