9-Hy-droxy-4,8-dimethyl-12-(piperidin-1-ylmeth-yl)-3,14-dioxatricyclo-[9.3.0.0]tetra-dec-7-en-13-one.

The title compound, C(20)H(31)NO(4), was synthesized from 9α-hy-droxy-parthenolide (9α-hy-droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tricyclo-[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 mol-ecule is built up from fused five-and ten-membered rings with the pipyridin-1-yl-methyl group as a substituent. The ten-membered ring adopts an approximate chair-chair conformation, while the six-membered ring display a chair conformation and the five-membered ring an envelope conformation with the C(H)-C-C(H) atom at the flap. The dihedral angle between the ten-membered ring and the lactone ring is 21.7 (4)°. The mol-ecular conformation is stabilized by an O-H⋯N hydrogen bond and the crystal structure is stabilized by weak inter-molecular C-H⋯O inter-actions.