| Summary: | The title compound, C21H27NO4, was synthesized from 9α-hydroxyparthenolide, which was isolated from the chloroform extract of the aerial parts of Anvillea radiata. The asymmetric unit contains two independent molecules. In each, the ten-membered ring displays an approximative chair-chair conformation. Each of the five-membered rings adopts 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 0.443 (2) and 0.553 (2) Å. The dihedral angle between the least-squares planes through the ten- and five-membered rings in the two molecules are similar [22.54 (17) and 23.39 (14)°]. In the crystal, molecules are linked by O—H...O, O—H...N and N—H...O hydrogen bonds.
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