5,9-Dihy­droxy-9-methyl-3,6-dimethyl­ene-3a,4,5,6,6a,7,8,9,9a,9b-deca­hydro­azuleno[4,5-b]furan-2(3H)-one

The title compound, C15H20O4, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methyl­ene-3,14-dioxatricyclo­[9.3.0.02,4]tetra­dec-7-en-13-one), which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The seven-membered ring has a chair conformation, while the five-membered rings display twisted conformations. The dihedral angle between the seven-membered ring and the lactone ring is 21.69 (10)°. In the crystal, mol­ecules are linked into chains propagating along the c axis by inter­molecular O—H⋯O hydrogen bonds; an intra­molecular O—H⋯O link also occurs

Methyl 2-(3a,8a-dimethyl-4-oxodeca­hydro­azulen-6-yl)acrylate

The title compound, C16H24O3, was synthesized from ilicic acid, which was isolated from the aerial part of Inula viscosa­ (L) Aiton [or Dittrichia viscosa­ (L) Greuter]. The asymmetric unit contains two independent mol­ecules, in each of which the seven-membered ring shows a chair conformation, whereas the five-membered ring presents disorder. In the two molecules, three C atoms in the five-membered ring are disordered over two positions with site-occupancy factors of 0.53/0.47 and 0.83/0.17. The dihedral angle between the two rings is different in the two mol­ecules [31.7 (3) and 47.7 (7)°]. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen-bond inter­actions

2-Isopropyl-4-meth­oxy-5-methyl­phenyl benzoate

The title compound, C18H20O3, a hemisynthetic product, was obtained by the reaction of benzoyl chloride and p-methoxy­thymol. The structure comprises two benzene rings bridged by a carboxyl group; the dihedral angle between the rings is 73.54 (8)°

9-Hy­droxy-4,8-dimethyl-12-(piperidin-1-ylmeth­yl)-3,14-dioxatricyclo­[9.3.0.02,4]tetra­dec-7-en-13-one

The title compound, C20H31NO4, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tricyclo­[9.3.0.02,4]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 the pipyridin-1-yl-methyl group as a substituent. The ten-membered ring adopts an approximate chair–chair conformation, while the six-membered ring display a chair conformation and the five-membered ring an envelope conformation with the C(H)–C–C(H) atom at the flap. The dihedral angle between the ten-membered ring and the lactone ring is 21.7 (4)°. The mol­ecular conformation is stabilized by an O—H⋯N hydrogen bond and the crystal structure is stabilized by weak inter­molecular C—H⋯O inter­actions

3-[4-(Dimethyl­amino)­phen­yl]-1-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octa­hydro­naphthalen-2-yl)prop-2-en-1-one

The title compound, C23H31NO, was semisynthesized from isocostic acid, isolated from the aerial part of Inula Viscosa­ (L) Aiton [or Dittrichia Viscosa­ (L) Greuter]. The cyclo­hexene ring has a half-chair conformation, whereas the cyclo­hexane ring displays a chair conformation. The dihedral angle between the latter ring and its substituent is 83.6 (7)°

1-(4a,8-Dimethyl-1,2,3,4,4a,5,6,8a-octa­hydro­naphthalen-2-yl)-3-phenyl­prop-2-en-1-one

The title compound, C21H26O, was semisynthesized from isocostic acid, isolated from the aerial part of Inula Viscosa­ (L) Aiton [or Dittrichia Viscosa­ (L) Greuter]. The cyclo­hexene ring has a half-chair conformation, whereas the cyclo­hexane ring displays a chair conformation

(Z)-6-Hy­droxy-1a,5-dimethyl-8-[(morpholin-4-yl)meth­yl]-2,3,6,7,7a,8,10a,10b-octa­hydro­oxireno[2′,3′:9,10]cyclo­deca­[1,2-b]furan-9(1aH)-one

The title compound, C19H29NO5, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methylen-3,14-dioxatricyclo­[9.3.0.02,4]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 two fused five- and ten-membered rings with the (morpholin-4-yl)methyl group as a substituent. The five-membered lactone ring has an envelope conformation, whereas the ten-membered and the morpholine rings display approximate chair–chair and chair conformations, respectively. The dihedral angle between the ten-membered ring and the lactone ring is 27.93 (6)°. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen-bond inter­actions. An intra­molecular O—H⋯N hydrogen bond also occurs

10α-Hy­droxy-4,9-dimethyl-13-[(4-phenyl­piperazin-1-yl)meth­yl]-3,8,15-trioxatetra­cyclo­[10.3.0.02,4.07,9]tetra­decan-14-one

The title compound, C25H34N2O5, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methyl­ene-3,14-dioxatricyclo­[9.3.0.02,4]tetra­dec-7-en-13-one), which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The mol­ecule contains a fused five- and ten-membered ring system. The ten-membered ring adopts an approximate chair–chair conformation, while the five-membered ring is in an envelope conformation, with the C atom closest to the hy­droxy group forming the flap. The piperazine ring is in a chair conformation. In the crystal, O—H⋯O hydrogen bonds connect mol­ecules into chains along [100]. Weak inter­molecular C—H⋯O hydrogen bonds are also present

5,8-Dimethyl-3-methyl­ene-2-oxo-3,3a,4,5,5a,6,8a,8b-octa­hydro-2H-1-oxa-s-indacene-5-carbaldehyde

The title compound, C15H18O3, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methyl­ene-3,14-dioxatricyclo­[9.3.0.02,4]tetra­dec-7-en-13-one), which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The five-membered lactone ring has a twisted conformation, while the six- and five-membered rings display chair and envelope conformations, respectively. The dihedral angle between the two five-membered rings is 50.57 (11)°

10α-Hy­droxy-4,9-dimethyl-13-(pipyridin-1-ylmethyl)-3,8,15-trioxatetra­cyclo­[10.3.0.02,4.07,9]tetra­decan-14-one

The title compound, C20H31NO5, was synthesized from 9α-hy­droxy­parthenolide (9α-hy­droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tricyclo­[9.3.0.02,4]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 the pipyridin-1-yl-methyl group as a substituent. The ten-membered ring adopts an approximate chair–chair conformation, while the six- and five-membered rings display chair and envelope conformations, respectively. The dihedral angle between the mean planes of the ten-membered ring and the lactone ring is 20.8 (3)°. An intra­molecular O—H⋯N hydrogen-bond occurs. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds