Received 11 September 2013
aDepartment of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA,bDepartment of Chemistry, University of Kentucky, Lexington, KY 40506, USA, and cCollege of Medicine, Department of Physiology & Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
Correspondence e-mail: firstname.lastname@example.org
The title compound, C21H25NO3 [systematic name: (3aS,9aR,10aR,10bS,E)-3-[(E)-4-(4-aminobenzylidene)-6,9a-dimethyl-3a,4,5,8,9,9a,10a,10b-octahydrooxireno[2',3':9,10]cyclodeca[1,2-b]furan-2(3H)-one] was obtained from the reaction of parthenolide [synonym: 4,5-epoxygermacra-1(10),11(13)-dieno-12,6-lactone] with 4-iodoaniline under Heck reaction conditions. It was identified as the E-isomer (conformation about the exocyclic methylidene C=C bond; the conformation about the C=C bond in the ten-membered ring is also E). The molecule is built up from fused ten-, five- (lactone) and three-membered (epoxide) rings with a 4-aminophenyl group as a substituent. The ten-membered ring displays an approximate chair-chair conformation, while the lactone ring has an envelope conformation with the C atom bonded to the ring O atom as the flap. The dihedral angle between the benzene ring of the 4-aminophenyl moiety and the lactone ring mean plane is 23.50 (8)°. In the crystal, molecules are linked via N-HO hydrogen bonds, between the amine group and the lactone and epoxide ring O atoms, forming chains propagating along the b-axis direction. Adjacent chains are linked via C-HO interactions, forming an undulating two-dimensional network lying parallel to the plane (001). The absolute structure of the molecule in the crystal was confirmed by resonance scattering [Flack parameter = 0.03 (3)].
For the biological activity of parthenolide, see: Hall et al. (1979). For the biological activity of parthenolide derivatives similar to the title compound, see: Hanson et al. (1970); Hehner et al. (1998); Kupchan et al. (1971); Nasim et al. (2011); Neelakantan et al. (2009); Oka et al. (2007); Ralstin et al. (2006); Rodriguez et al. (1976); Sun et al. (2006). For the synthesis and crystal structures of similar molecules, see: Han et al. (2009).
Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2647 ).
This work was supported by NIH/NCI [grant No. CA158275].
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