Crystal structure of (1S,2R,4R,9S,11S,-12R)-9α-hydroxy-4,8-dimethyl-12-[(thio-morpholin-4-yl)methyl]-3,14-dioxatri-cyclo[9.3.0.0^2,4]tetradec-7-en-13-one

The title compound, C₁₉H₂₉NO₄S, was synthesised from 9a-hydroxyparthenolide (9α-hydroxy-4, 8-dimethyl-12-methyl-ene-3, 14-dioxatricyclo[9.3.0.0^2.4]tetradec-7-en-13-one), which was isolated from the chloroform extract of the aerial parts of the plant Anvillea radiata. The molecule is built up from two fused five- and ten-membered rings, with an additional epoxy ring system and a thiomorpholine group as a substituent. The ten-membered ring adopts an approximate chair-chair conformation, while the thiomorpholine ring displays a chair conformation and the five-membered ring has an envelope conformation, with the C atom closest to the hydroxy group forming the flap. An intramolecular O - H⋯N hydrogen bond closes an S(8) ring. The crystal structure features weak C - H⋯O hydrogen-bonding interactions, which link the molecules into [010] chains.