9β-Hy­droxy-6,9-dimethyl-3-methyl­ene-3a,4,8,9,9a,9b-hexa­hydro­azuleno[4,5-b]furan-2(3H)-one

The title compound, C₁₅H₁₈O₃, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tricyclo­[9.3.0.0^2,4]tetra­dec-7-en-13-one), which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The seven-membered ring of the title compound shows a chair conformation, while the five-membered rings exibit different conformations, viz a twisted one for the lactone ring and an envelope conformation for the other five-membered ring with the C atom closest to the hydroxy group forming the flap. In the crystal, O—H...O hydrogen bonds connect mol­ecules into dimers that are inter­connected by C—H...O inter­actions, producing supramolecular chains along the b axis.

Methyl 2-(1a,4a-dimethyl-2,8-dioxo-2,3,4,4a,5,6,7,8-octa­hydro-1aH-1-oxacyclo­propa[d]naphthalen-7-yl)acrylate

The title compound, C₁₆H₂₀O₅, was synthesized from ilicic acid [2-(8-hy­droxy-4a,8-dimethyl­deca­hydro­naphthalen-2-yl)acrylic acid], which was isolated from the chloro­form extract of the aerial part of Inula viscose (L) Aiton [or Dittrichia viscosa­ (L) Greuter]. The molecule is built up from two fused six-membered rings, the epoxidized six-membered ring adopts a half-chair conformation while the other ring displays a perfect chair conformation. The crystal structure features C—H...O hydrogen bonds.

10α-Hy­droxy-13-{[4-(4-meth­oxy­phen­yl)piperazin-1-yl]meth­yl}-4,9-dimethyl-3,8,15-trioxatetra­cyclo­[10.3.0.0^2,4.0^7,9]penta­decan-14-one

The title compound, C₂₆H₃₆N₂O₆, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tricyclo­[9.3.0.0^2,4]tetra­dec-7-en-13-one), which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The mol­ecule is built up from fused five- and ten-membered rings with two additional ep­oxy ring systems and a meth­oxy­phenyl­piperazine group as a substituent. The ten-membered ring adopts an approximate chair–chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring shows an envelope conformation with the C atom closest to the hy­droxy group forming the flap. The mol­ecular conformation is determined by an O—H...N hydrogen bond between the hy­droxy group and a piperazine N atom. The crystal structure is built up by weak C—H...O inter­actions.

12-{[4-(2-Fluoro­phen­yl)piperazin-1-yl]­meth­yl}-9α-hy­droxy-4,8-dimethyl-3,14-dioxatricyclo­[9.3.0.0^2,4]tetra­dec-7-en-13-one

The title compound, C₂₅H₃₃FN₂O₄, was synthesized 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 Anvillea radiata. The asymmetric unit contains two independent mol­ecules. In each mol­ecule, the ten-membered ring displays an approximative chair–chair conformation. Each of the piperazine rings adopts a perfect chair conformation, while both lactone rings show an envelope conformation, one with the C atom bearing the piperazin-1-ylmethyl group as the flap, the other with the junction C atom not attached to the ring O atom as the flap. The dihedral angles between the least-squares planes through the ten- and five-membered rings in the two mol­ecules are similar [19.1 (3) and 16.2 (3)°]. An intra­molecular O—H...N hydrogen bond stabilizes the mol­ecular conformation. The crystal packing is stabilized by C—H...O hydrogen bonds.