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

The title compound, C(19)H(29)O(4), was synthesized from 9α-hy-droxy-parthenolide (9α-hy-droxy-4,8-dimethyl-12-methylen-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 mol-ecule is built up from two fused five- and ten-membered rings with the pyrrolidin-1-ylmethyl group as a substituent. The five-membered lactone ring has an envelope conformation, whereas the ten-membered and pyrrolidine rings display approximate chair-chair and twisted conformations, respectively. The dihedral angle between the ten-membered ring and the lactone ring is 18.01 (19)°. An intra-molecular O-H⋯N hydrogen bond occurs. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen-bonding inter-actions.