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

The title compound, C(19)H(29)NO(4)S, was synthesised from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methyl­ene-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.