organic compounds
(1S,2R,3R,8R,10S)-3-Chloro-2,8-dihydroxy-3,7-dimethyl-11-methylidene-13-oxabicyclo[8.3.0]tridec-6-en-12-one
aLaboratoire de Chimie Biomoleculaire, Substances Naturelles et Réactivité, URAC16, Faculté des Sciences Semlalia, BP 2390 Bd My Abdellah, 40000 Marrakech, Morocco, bLaboratoire de Chimie de Coordination, 205 route de Narbonne, 31077 Toulouse Cedex 04, France, and cLaboratoire de Chimie Bioorganique et Analytique, URAC 22. BP 146, FSTM, Université Hassan II, Mohammedia–Casablanca 20810 Mohammedia, Morocco
*Correspondence e-mail: mberraho@yahoo.fr
The title compound, C15H21ClO4, 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 fused five- and ten-membered rings. The five-membered lactone ring has an with the flap atom, C(H)-C-C(H), displaced by 0.2325 (15) Å from the mean plane through the remaining four atoms, whereas the ten-membered ring displays an approximate chair–chair conformation. The dihedral angle between the two rings is 66.4 (2)°. In the crystal, molecules are linked into chains propagating along the a axis by O—H⋯O hydrogen bonds.
Related literature
For the isolation and biological activity of 9α-hydroxyparthenolide, see: El Hassany et al. (2004). For the reactivity of this sesquiterpene, see: Castaneda-Acosta et al. (1993); Neukirch et al. (2003); Hwang et al. (2006); Neelakantan et al. (2009). For see: Cremer & Pople (1975)
Experimental
Crystal data
|
Data collection: CrysAlis PRO (Agilent, 2010); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
10.1107/S1600536811039717/im2319sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811039717/im2319Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536811039717/im2319Isup3.cml
To a solution of 9α-hydroxyparthenolide (500 mg, 1.89 mmol) in 20 ml dichloromethane are added in small portions and carefully a catalytic amount (5%) of titanium tetrachloride (TiCl4). The reaction mixture was kept at room temperature and stirred for 3 h. Afterwards it was hydrolysed with 20 ml of water and extracted three times with dichloromethane (20 mL). The organic phases are combined, dried over anhydrous Na2SO4 and then evaporated under reduced pressure. The resulting residue is purified by on silica gel with hexane /ethyl acetate (30/70) as This allowed us to isolate in pure 291 mg (0,98 mmol, 52%) of (1S, 2R, 3R, 8R, 10S)-3-chloro-2,8-dihydroxy-3,7-dimethyl-11-methylene- 13-oxabicyclo[8.3.0]tridec-6-en-12-one. The title compound was recrystallized from ethyl acetate to produce crystals suitable for X-ray diffraction.
All H atoms were fixed geometrically and treated as riding with C—H = 0.96 Å (methyl), 0.97 Å (methylene), 0.98 Å (methine) and O–H = 0.82 Å with Uiso(H) = 1.2Ueq(methylene, methine) or Uiso(H) = 1.5Ueq (methyl, OH).
Data collection: CrysAlis PRO (Agilent, 2010); cell
CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 1999).C15H21ClO4 | F(000) = 640 |
Mr = 300.77 | Dx = 1.329 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 8982 reflections |
a = 8.0224 (2) Å | θ = 3.6–26.4° |
b = 12.1532 (2) Å | µ = 0.26 mm−1 |
c = 15.4147 (4) Å | T = 180 K |
V = 1502.90 (6) Å3 | Prism, colourless |
Z = 4 | 0.35 × 0.27 × 0.17 mm |
Agilent Xcalibur Eos Gemini ultra diffractometer | 3053 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 2944 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.019 |
Detector resolution: 16.1978 pixels mm-1 | θmax = 26.4°, θmin = 3.6° |
ω scans | h = −10→9 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010) | k = −15→15 |
Tmin = 0.889, Tmax = 1.000 | l = −18→19 |
8982 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.027 | H-atom parameters constrained |
wR(F2) = 0.070 | w = 1/[σ2(Fo2) + (0.0362P)2 + 0.3492P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max = 0.001 |
3053 reflections | Δρmax = 0.21 e Å−3 |
185 parameters | Δρmin = −0.21 e Å−3 |
0 restraints | Absolute structure: Flack (1983), 614 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.06 (5) |
C15H21ClO4 | V = 1502.90 (6) Å3 |
Mr = 300.77 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 8.0224 (2) Å | µ = 0.26 mm−1 |
b = 12.1532 (2) Å | T = 180 K |
c = 15.4147 (4) Å | 0.35 × 0.27 × 0.17 mm |
Agilent Xcalibur Eos Gemini ultra diffractometer | 3053 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010) | 2944 reflections with I > 2σ(I) |
Tmin = 0.889, Tmax = 1.000 | Rint = 0.019 |
8982 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | H-atom parameters constrained |
wR(F2) = 0.070 | Δρmax = 0.21 e Å−3 |
S = 1.04 | Δρmin = −0.21 e Å−3 |
3053 reflections | Absolute structure: Flack (1983), 614 Friedel pairs |
185 parameters | Absolute structure parameter: −0.06 (5) |
0 restraints |
Experimental. Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. CrysAlisPro (Agilent, 2010) |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Cl | 0.47204 (6) | 0.42068 (3) | 0.58743 (3) | 0.03475 (11) | |
C1 | 0.60869 (16) | 0.59828 (11) | 0.36912 (9) | 0.0169 (3) | |
H1 | 0.6725 | 0.5379 | 0.3432 | 0.020* | |
C2 | 0.55399 (17) | 0.56590 (10) | 0.46192 (9) | 0.0169 (3) | |
H2 | 0.6465 | 0.5833 | 0.5011 | 0.020* | |
C3 | 0.51598 (18) | 0.44248 (11) | 0.47165 (9) | 0.0193 (3) | |
C4 | 0.66321 (18) | 0.36766 (11) | 0.44947 (11) | 0.0226 (3) | |
H4A | 0.6774 | 0.3691 | 0.3870 | 0.027* | |
H4B | 0.6322 | 0.2931 | 0.4651 | 0.027* | |
C5 | 0.83398 (18) | 0.39143 (12) | 0.49062 (11) | 0.0271 (3) | |
H5A | 0.8208 | 0.3935 | 0.5532 | 0.033* | |
H5B | 0.9085 | 0.3310 | 0.4770 | 0.033* | |
C6 | 0.91472 (16) | 0.49718 (12) | 0.46184 (10) | 0.0211 (3) | |
H6 | 0.9289 | 0.5519 | 0.5034 | 0.025* | |
C7 | 0.96724 (17) | 0.51863 (11) | 0.38212 (10) | 0.0201 (3) | |
C8 | 1.01946 (18) | 0.63373 (12) | 0.35599 (10) | 0.0213 (3) | |
H8 | 1.1106 | 0.6281 | 0.3139 | 0.026* | |
C9 | 0.87577 (18) | 0.69698 (12) | 0.31401 (10) | 0.0231 (3) | |
H9A | 0.8484 | 0.6619 | 0.2593 | 0.028* | |
H9B | 0.9135 | 0.7711 | 0.3012 | 0.028* | |
C10 | 0.71583 (16) | 0.70436 (11) | 0.36933 (10) | 0.0181 (3) | |
H10 | 0.7458 | 0.7230 | 0.4292 | 0.022* | |
C11 | 0.59596 (18) | 0.78895 (13) | 0.33507 (10) | 0.0228 (3) | |
C12 | 0.44945 (19) | 0.73049 (13) | 0.29884 (11) | 0.0264 (3) | |
C13 | 0.6075 (2) | 0.89766 (13) | 0.33538 (12) | 0.0329 (4) | |
H13A | 0.5217 | 0.9401 | 0.3123 | 0.039* | |
H13B | 0.7013 | 0.9316 | 0.3587 | 0.039* | |
C14 | 0.9722 (2) | 0.43627 (13) | 0.30957 (11) | 0.0296 (3) | |
H14A | 0.9579 | 0.3636 | 0.3327 | 0.044* | |
H14B | 1.0777 | 0.4409 | 0.2804 | 0.044* | |
H14C | 0.8842 | 0.4517 | 0.2692 | 0.044* | |
C15 | 0.36070 (18) | 0.40750 (12) | 0.42250 (11) | 0.0267 (3) | |
H15A | 0.3759 | 0.4215 | 0.3617 | 0.040* | |
H15B | 0.2666 | 0.4485 | 0.4433 | 0.040* | |
H15C | 0.3415 | 0.3304 | 0.4314 | 0.040* | |
O1 | 0.33335 (15) | 0.76689 (11) | 0.25906 (9) | 0.0408 (3) | |
O2 | 0.46321 (13) | 0.62157 (8) | 0.31574 (7) | 0.0235 (2) | |
O3 | 0.41528 (12) | 0.63183 (8) | 0.48730 (7) | 0.0219 (2) | |
H3 | 0.4483 | 0.6844 | 0.5159 | 0.033* | |
O4 | 1.07598 (12) | 0.69787 (8) | 0.42835 (8) | 0.0261 (2) | |
H4 | 1.1646 | 0.6730 | 0.4461 | 0.039* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl | 0.0427 (2) | 0.03388 (19) | 0.0276 (2) | 0.00420 (18) | 0.00966 (18) | 0.00940 (16) |
C1 | 0.0124 (6) | 0.0175 (6) | 0.0206 (7) | 0.0001 (5) | −0.0032 (5) | 0.0002 (5) |
C2 | 0.0130 (6) | 0.0169 (6) | 0.0208 (7) | 0.0019 (5) | 0.0001 (5) | −0.0004 (5) |
C3 | 0.0188 (7) | 0.0195 (6) | 0.0195 (7) | 0.0008 (5) | 0.0027 (6) | 0.0042 (5) |
C4 | 0.0204 (7) | 0.0152 (6) | 0.0322 (8) | 0.0012 (5) | 0.0019 (6) | 0.0009 (6) |
C5 | 0.0201 (7) | 0.0237 (8) | 0.0374 (9) | 0.0051 (6) | −0.0026 (7) | 0.0084 (6) |
C6 | 0.0134 (6) | 0.0208 (6) | 0.0290 (8) | 0.0032 (5) | −0.0038 (6) | −0.0013 (6) |
C7 | 0.0109 (6) | 0.0205 (6) | 0.0289 (8) | 0.0014 (5) | −0.0007 (6) | −0.0065 (6) |
C8 | 0.0150 (7) | 0.0231 (7) | 0.0257 (7) | −0.0018 (5) | 0.0029 (6) | −0.0057 (6) |
C9 | 0.0200 (7) | 0.0253 (7) | 0.0240 (8) | −0.0045 (6) | 0.0034 (6) | 0.0022 (6) |
C10 | 0.0155 (6) | 0.0179 (6) | 0.0208 (7) | −0.0011 (5) | −0.0002 (6) | 0.0018 (6) |
C11 | 0.0201 (7) | 0.0255 (7) | 0.0228 (8) | 0.0007 (6) | 0.0026 (6) | 0.0061 (6) |
C12 | 0.0217 (7) | 0.0308 (8) | 0.0267 (8) | −0.0005 (6) | 0.0007 (7) | 0.0100 (6) |
C13 | 0.0331 (9) | 0.0247 (8) | 0.0408 (10) | 0.0031 (7) | 0.0023 (8) | 0.0073 (7) |
C14 | 0.0240 (8) | 0.0288 (8) | 0.0361 (9) | −0.0018 (6) | 0.0042 (7) | −0.0135 (7) |
C15 | 0.0191 (7) | 0.0201 (7) | 0.0410 (9) | −0.0039 (6) | −0.0041 (7) | 0.0039 (7) |
O1 | 0.0255 (6) | 0.0461 (7) | 0.0507 (8) | 0.0016 (5) | −0.0121 (6) | 0.0243 (6) |
O2 | 0.0193 (5) | 0.0256 (5) | 0.0255 (5) | −0.0039 (4) | −0.0078 (5) | 0.0052 (4) |
O3 | 0.0156 (5) | 0.0193 (5) | 0.0308 (6) | 0.0022 (4) | 0.0021 (4) | −0.0050 (4) |
O4 | 0.0169 (5) | 0.0233 (5) | 0.0380 (7) | 0.0005 (4) | −0.0052 (4) | −0.0100 (5) |
Cl—C3 | 1.8384 (15) | C8—C9 | 1.529 (2) |
C1—O2 | 1.4557 (16) | C8—H8 | 0.9800 |
C1—C2 | 1.5471 (19) | C9—C10 | 1.5433 (19) |
C1—C10 | 1.5495 (18) | C9—H9A | 0.9700 |
C1—H1 | 0.9800 | C9—H9B | 0.9700 |
C2—O3 | 1.4260 (16) | C10—C11 | 1.504 (2) |
C2—C3 | 1.5380 (18) | C10—H10 | 0.9800 |
C2—H2 | 0.9800 | C11—C13 | 1.324 (2) |
C3—C15 | 1.519 (2) | C11—C12 | 1.483 (2) |
C3—C4 | 1.5292 (19) | C12—O1 | 1.1997 (19) |
C4—C5 | 1.537 (2) | C12—O2 | 1.3536 (18) |
C4—H4A | 0.9700 | C13—H13A | 0.9300 |
C4—H4B | 0.9700 | C13—H13B | 0.9300 |
C5—C6 | 1.506 (2) | C14—H14A | 0.9600 |
C5—H5A | 0.9700 | C14—H14B | 0.9600 |
C5—H5B | 0.9700 | C14—H14C | 0.9600 |
C6—C7 | 1.325 (2) | C15—H15A | 0.9600 |
C6—H6 | 0.9300 | C15—H15B | 0.9600 |
C7—C14 | 1.5014 (19) | C15—H15C | 0.9600 |
C7—C8 | 1.5148 (19) | O3—H3 | 0.8200 |
C8—O4 | 1.4343 (17) | O4—H4 | 0.8200 |
O2—C1—C2 | 110.16 (11) | O4—C8—H8 | 108.5 |
O2—C1—C10 | 106.51 (10) | C7—C8—H8 | 108.5 |
C2—C1—C10 | 111.53 (11) | C9—C8—H8 | 108.5 |
O2—C1—H1 | 109.5 | C8—C9—C10 | 114.96 (12) |
C2—C1—H1 | 109.5 | C8—C9—H9A | 108.5 |
C10—C1—H1 | 109.5 | C10—C9—H9A | 108.5 |
O3—C2—C3 | 111.50 (11) | C8—C9—H9B | 108.5 |
O3—C2—C1 | 109.40 (11) | C10—C9—H9B | 108.5 |
C3—C2—C1 | 113.23 (11) | H9A—C9—H9B | 107.5 |
O3—C2—H2 | 107.5 | C11—C10—C9 | 112.17 (12) |
C3—C2—H2 | 107.5 | C11—C10—C1 | 102.32 (11) |
C1—C2—H2 | 107.5 | C9—C10—C1 | 114.31 (12) |
C15—C3—C4 | 110.83 (12) | C11—C10—H10 | 109.3 |
C15—C3—C2 | 112.77 (11) | C9—C10—H10 | 109.3 |
C4—C3—C2 | 113.89 (11) | C1—C10—H10 | 109.3 |
C15—C3—Cl | 106.66 (10) | C13—C11—C12 | 122.32 (15) |
C4—C3—Cl | 106.23 (10) | C13—C11—C10 | 129.51 (15) |
C2—C3—Cl | 105.86 (9) | C12—C11—C10 | 108.16 (13) |
C3—C4—C5 | 118.97 (12) | O1—C12—O2 | 121.48 (15) |
C3—C4—H4A | 107.6 | O1—C12—C11 | 129.15 (15) |
C5—C4—H4A | 107.6 | O2—C12—C11 | 109.36 (13) |
C3—C4—H4B | 107.6 | C11—C13—H13A | 120.0 |
C5—C4—H4B | 107.6 | C11—C13—H13B | 120.0 |
H4A—C4—H4B | 107.0 | H13A—C13—H13B | 120.0 |
C6—C5—C4 | 114.97 (12) | C7—C14—H14A | 109.5 |
C6—C5—H5A | 108.5 | C7—C14—H14B | 109.5 |
C4—C5—H5A | 108.5 | H14A—C14—H14B | 109.5 |
C6—C5—H5B | 108.5 | C7—C14—H14C | 109.5 |
C4—C5—H5B | 108.5 | H14A—C14—H14C | 109.5 |
H5A—C5—H5B | 107.5 | H14B—C14—H14C | 109.5 |
C7—C6—C5 | 125.30 (14) | C3—C15—H15A | 109.5 |
C7—C6—H6 | 117.3 | C3—C15—H15B | 109.5 |
C5—C6—H6 | 117.3 | H15A—C15—H15B | 109.5 |
C6—C7—C14 | 124.62 (13) | C3—C15—H15C | 109.5 |
C6—C7—C8 | 121.08 (13) | H15A—C15—H15C | 109.5 |
C14—C7—C8 | 114.22 (12) | H15B—C15—H15C | 109.5 |
O4—C8—C7 | 112.49 (12) | C12—O2—C1 | 111.36 (11) |
O4—C8—C9 | 107.12 (11) | C2—O3—H3 | 109.5 |
C7—C8—C9 | 111.61 (12) | C8—O4—H4 | 109.5 |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O4i | 0.82 | 1.96 | 2.763 (1) | 167 |
O4—H4···O3ii | 0.82 | 2.17 | 2.980 (1) | 171 |
Symmetry codes: (i) x−1/2, −y+3/2, −z+1; (ii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C15H21ClO4 |
Mr | 300.77 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 180 |
a, b, c (Å) | 8.0224 (2), 12.1532 (2), 15.4147 (4) |
V (Å3) | 1502.90 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.26 |
Crystal size (mm) | 0.35 × 0.27 × 0.17 |
Data collection | |
Diffractometer | Agilent Xcalibur Eos Gemini ultra diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Agilent, 2010) |
Tmin, Tmax | 0.889, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8982, 3053, 2944 |
Rint | 0.019 |
(sin θ/λ)max (Å−1) | 0.625 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.070, 1.04 |
No. of reflections | 3053 |
No. of parameters | 185 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.21, −0.21 |
Absolute structure | Flack (1983), 614 Friedel pairs |
Absolute structure parameter | −0.06 (5) |
Computer programs: CrysAlis PRO (Agilent, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009), WinGX (Farrugia, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O4i | 0.82 | 1.96 | 2.763 (1) | 167 |
O4—H4···O3ii | 0.82 | 2.17 | 2.980 (1) | 171 |
Symmetry codes: (i) x−1/2, −y+3/2, −z+1; (ii) x+1, y, z. |
Acknowledgements
The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for financial support.
References
Agilent (2010). CrysAlis PRO. Agilent Technologies, Yarnton, England. Google Scholar
Castaneda-Acosta, J., Fisher, N. H. & Varga, D. (1993). J. Nat. Prod. 56, 90–98. CrossRef CAS PubMed Web of Science Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
El Hassany, B., El Hanbali, F., Akssira, M., Mellouki, F., Haidou, A. & Barero, A. F. (2004). Fitoterapia, 75, 573–576. Web of Science CrossRef PubMed CAS Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Hwang, D.-R., Wu, Y.-S., Chang, C.-W., Lien, T.-W., Chen, W.-C., Tan, U.-K., Hsu, J. T. A. & Hsieh, H.-P. (2006). Bioorg. Med. Chem. 14, 83–91. Web of Science CrossRef PubMed CAS Google Scholar
Neelakantan, S., Nasim, Sh., Guzman, M. L., Jordan, C. T. & Crooks, P. A. (2009). Bioorg. Med. Chem. Lett. 19, 4346–4349. Web of Science CrossRef PubMed CAS Google Scholar
Neukirch, H., Kaneider, N. C., Wiedermann, C. J., Guerriero, A. & D'Ambrosio, M. (2003). Bioorg. Med. Chem. 11, 1503–1510. Web of Science CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Our work lies within the framework of the evaluation of medicinal plants and in particular, Anvillea radiata. The main constituent of the chloroform extract of the aerial parts of Anvillea radiata is 9α-hydroxyparthenolide (El Hassany et al., 2004). The reactivity of this sesquiterpene lactone and its derivatives has been the subject of several studies (Castaneda-Acosta et al., 1993; Neukirch et al., 2003; Hwang et al., 2006; Neelakantan et al., 2009), in order to prepare products with a high added value that can be used in the pharmacological industry. In the same context, we have treated 9α-hydroxyparthenolide with 5% of titanium tetrachloride (TiCl4)and obtained (1S, 2R, 3R, 8R, 10S)-3-chloro-2,8- dihydroxy-3,7-dimethyl-11-methylene-13-oxabicyclo[8.3.0]tridec-6-en-12-one with a yield of 52%. The structure of this new product was determined by its single-crystal X-ray structure. The molecule contains two fused rings which exhibit different conformations. The molecular structure of the title compound, Fig.1, shows the lactone ring to adopt an envelope conformation, as indicated by Cremer & Pople (1975) puckering parameters QT = 0.147 (2) Å and ϕ2 = 58.1 (5)°. The ten-membered ring displays an approximate chair-chair conformation.In the crystal structure, molecules are linked into chains (Fig. 2) running along the a axis by intermolecular O—H···O hydrogen bonds (Table 1). Owing to the presence of Cl atom, the absolute configuration could be fully confirmed, by refining the Flack parameter (Flack, 1983) as C1(S), C2(R), C3(R), C8(R)and C10(S).