(20S)-20-Acet-oxy-4-pregnene-3,16-dione from Commiphora wightii.

Abstract

The title triterpene compound, C(23)H(32)O(4), isolated from Commiphora wightii features four trans-fused rings, among which the five-membered ring adopts an envelope conformation, the cyclo-hexene ring adopts a half-chair conformation and the two cyclo-hexane rings exist in chair conformations. The asymmetric unit contains two independent mol-ecules. Weak inter-molecular C-H⋯O hydrogen bonding is present in the crystal structure.

Full text

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(20S)-20-Acetoxy-4-pregnene-3,16-dione
from Commiphora wightii
Sammer Yousuf,aRida Ahmed,aZulfiqar Ali,aM. Iqbal
Choudharyaand Seik Weng Ngb*
aH.E.J. Research Institute of Chemistry, International Center for Chemical and
Biological Sciences, University of Karachi, Karachi 75270, Pakistan, and
bDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
Correspondence e-mail: seikweng@um.edu.my
Received 16 November 2010; accepted 17 November 2010
Key indicators: single-crystal X-ray study; T = 293 K; mean ?(C–C) = 0.004 A ˚;
R factor = 0.041; wR factor = 0.111; data-to-parameter ratio = 6.9.
The title triterpene compound, C23H32O4, isolated from
Commiphora wightii features four trans-fused rings, among
which the five-membered ring adopts an envelope conforma-
tion, the cyclohexene ring adopts a half-chair conformation
and the two cyclohexane rings exist in chair conformations.
The asymmetric unit contains two independent molecules.
Weak intermolecular C—H???O hydrogen bonding is present
in the crystal structure.
Related literature
For the crystal structures of similar steroids and terpene
analogues and other related structures, see: Coiro et al. (1982);
Geise et al. (1966). For the isolation of the title compound
from other plants, see: Francis et al. (2004); Hung et al. (1995);
Zhu et al. (2001).
Experimental
Crystal data
C23H32O4
Mr= 372.49
Triclinic, P1
a = 8.2802 (4) A˚
b = 8.6819 (5) A˚
c = 14.1363 (7) A˚
? = 94.130 (1)?
? = 97.028 (1)?
? = 90.603 (1)?
V = 1005.78 (9) A˚3
Z = 2
Mo K? radiation
? = 0.08 mm?1
T = 293 K
0.4 ? 0.3 ? 0.2 mm
Data collection
Bruker SMART APEX
diffractometer
4968 measured reflections
3440 independent reflections
3340 reflections with I > 2?(I)
Rint= 0.028
Refinement
R[F2> 2?(F2)] = 0.041
wR(F2) = 0.111
S = 1.05
3440 reflections
495 parameters
3 restraints
H-atom parameters constrained
??max= 0.28 e A˚?3
??min= ?0.22 e A˚?3
Table 1
Hydrogen-bond geometry (A˚,?).
D—H???A
C23—H23B???O2i
C46—H46B???O6i
Symmetry code: (i) x þ 1;y;z.
D—H H???AD???AD—H???A
0.96
0.96
2.46
2.49
3.393 (4)
3.431 (4)
165
167
Data collection: SMART (Bruker, 2002); cell refinement: SAINT
(Bruker, 2002); data reduction: SAINT; program(s) used to solve
structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine
structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-
SEED (Barbour, 2001); software used to prepare material for
publication: publCIF (Westrip, 2010).
We acknowledge funding by the Pak-USAID Project
(Linkages of Centers for Chemical Sciences, grant No. 1–5/
ILS-US/HEC/2004) and the United States Food and Drug
Administration (FDA)Specific
(Agreement No. 5U01FD002071–08). We thank the Univer-
sity of Malaya for supporting this study.
Cooperative Research
Supplementary data and figures for this paper are available from the
IUCr electronic archives (Reference: XU5092).
References
Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191.
Bruker (2002). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin,
USA.
Coiro, V. M., Giglio, E., Mazza, F., Pavel, N. V. & Pochetti, G. (1982). Acta
Cryst. B38, 2615–2620.
Francis, J. A., Raja, S. N. & Nair, M. G. (2004). Chem. Biodivers. 1, 1842–1853.
Geise, H. J., Romers, C. & Rutten, E. W. M. (1966). Acta Cryst. 20, 249–257.
Hung, T., Stuppner, H., Ellmerer-Mu ¨ller, E. P., Scholz, D., Eigner, D. &
Manandhar, M. P. (1995). Phytochemistry, 39, 1403–1409.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.
Zhu, N., Rafi, M. M., DiPaloa, R. S., Xing, J. S., Chin, C.-K., Badmaey, V. G.,
Rosen, R. T. & Ho, C.-T. (2001). Phytochemistry, 56, 723–727.
organic compounds
Acta Cryst. (2010). E66, o3301 doi:10.1107/S1600536810047987 Yousuf et al.
o3301
Acta Crystallographica Section E
Structure Reports
Online
ISSN 1600-5368

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supplementary materials

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supplementary materials
sup-1
Acta Cryst. (2010). E66, o3301 [ doi:10.1107/S1600536810047987 ]
(20S)-20-Acetoxy-4-pregnene-3,16-dione from Commiphora wightii
S. Yousuf, R. Ahmed, Z. Ali, M. I. Choudhary and S. W. Ng
Comment
20(S)-Acetyloxy-4-pregnene-3,16-dione (Scheme I) has been isolated from the gum resin of Ailanthus grandis and Com-
miphora mukul (Francis et al., 2004; Hung et al., 1995). Commiphora wightii (Arnott.), a medicinal plant native to parts of
Pakistan and India (Zhu et al., 2001), also yields this compound. The triterpene, C23H32O4, features four trans fused-rings
A–D. Rings B and C exist in a chair conformation whereas ring A adopts a half-chair conformation and ring D an envelope
conformation. There are two independent molecules that have similar bond dimensions (Figs. 1 & 2). The stereochemistry
is that established in others steroids and terpenes (Coiro et al., 1982; Geise et al., 1966).
Experimental
Gum resin samples of Commiphora wightii were collected from different locations of Pakistan and India, and were deposited
at the National Center for Natural Products Research, University of Mississippi. Gum resin (1.5 kg) was extracted with
ethyl acetate (5.0 L × 72 h) at room temperature; the extract was evaporated to a brown gummy material (250 g). This was
subjected to silica-gel column-chromatography and eluted with hexane/ethyl acetate[19:1 (3 L), 9:1 (5 L), 4:1 (5 L), 7:3
(5 L), 1:1 (3 L), 0:1 (2 L)] and acetone (2 L) to yield 24 fractions. The seventeenth fraction was subjected to vapor-liquid
chromatography on silica followed by elution with methanol/water [3:2 (1.5 L), 13:7 (1.5 L), 7:3 (1 L), 4:1 (2 L), 9:1 (3 L)
and 1:0 (1 L)] and acetone (1 L)] to give 19 fractions. 20(S)-acetyloxy-4-pregnene-3,16-dione (10 mg) was obtained from
the sixth fraction and purified by recrystallization from methanol to furnish colorless crystals.
Refinement
Carbon-bound H-atoms were placed in calculated positions (C–H 0.93 to 0.98 Å) and were included in the refinement in
the riding model approximation, with U(H) set to 1.2–1.5U(C).
Figures
Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of one molecule of C23H32O4 at the 50% prob-
ability level; hydrogen atoms are drawn as spheres of arbitrary radius.
Fig. 2. Thermal ellipsoid plot (Barbour, 2001) of second molecule of C23H32O4 at the 50%
probability level; hydrogen atoms are drawn as spheres of arbitrary radius.

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supplementary materials
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(20S)-20-Acetoxy-4-pregnene-3,16-dione
Crystal data
C23H32O4
Mr = 372.49
Z = 2
F(000) = 404
Dx = 1.230 Mg m−3
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 3395 reflections
θ = 2.4–28.3°
µ = 0.08 mm−1
T = 293 K
Block, colorless
0.4 × 0.3 × 0.2 mm
Triclinic, P1
Hall symbol: P 1
a = 8.2802 (4) Å
b = 8.6819 (5) Å
c = 14.1363 (7) Å
α = 94.130 (1)°
β = 97.028 (1)°
γ = 90.603 (1)°
V = 1005.78 (9) Å3
Data collection
Bruker SMART APEX
diffractometer
Radiation source: fine-focus sealed tube
graphite
ω scans
4968 measured reflections
3440 independent reflections
3340 reflections with I > 2σ(I)
Rint = 0.028
θmax = 25.0°, θmin = 1.5°
h = −9→9
k = −10→9
l = −7→16
Refinement
Refinement on F2
Primary atom site location: structure-invariant direct
methods
Secondary atom site location: difference Fourier map
Hydrogen site location: inferred from neighbouring
sites
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.041
wR(F2) = 0.111
H-atom parameters constrained
S = 1.05
w = 1/[σ2(Fo2) + (0.080P)2 + 0.1003P]
where P = (Fo2 + 2Fc2)/3
(Δ/σ)max = 0.001
Δρmax = 0.28 e Å−3
Δρmin = −0.22 e Å−3
3440 reflections
495 parameters
3 restraints
Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The
cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds
in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used
for estimating esds involving l.s. planes.

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supplementary materials
sup-3
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
x
0.2485 (3)
−0.3659 (3)
0.1541 (2)
0.1920 (3)
1.0521 (3)
0.1200 (3)
0.5908 (2)
0.5936 (3)
0.1898 (4)
0.2111
0.2814
0.0947
0.1611 (4)
0.3192 (4)
0.4079
0.3077
0.3626 (4)
0.3864
0.4595
0.2258 (4)
0.0621 (4)
−0.0253
0.0292 (4)
−0.1438 (4)
−0.2171
−0.1566
−0.1890 (4)
−0.2987
−0.1860
−0.0702 (3)
−0.0778
0.1060 (3)
0.1089
0.2261 (4)
0.3336
0.2318
0.1786 (3)
0.1887
0.2527
0.0042 (3)
−0.0106 (4)
0.0221
0.0583
−0.1215
−0.1070 (3)
y
0.2488 (3)
0.3251 (3)
0.3512 (2)
0.5699 (3)
1.0060 (3)
0.9567 (2)
0.9323 (2)
0.7041 (3)
0.6166 (4)
0.6509
0.6425
0.6663
0.4405 (3)
0.3581 (4)
0.4015
0.2496
0.3723 (4)
0.4796
0.3136
0.3138 (4)
0.3419 (4)
0.3167
0.4017 (3)
0.4368 (4)
0.3968
0.5478
0.3649 (4)
0.3933
0.2532
0.4211 (3)
0.5335
0.3806 (3)
0.2677
0.4297 (3)
0.3936
0.5416
0.3666 (3)
0.2552
0.4092
0.4081 (3)
0.5830 (3)
0.6368
0.6148
0.6064
0.3466 (3)
z
0.00029 (16)
0.65217 (16)
0.75785 (14)
0.85416 (18)
1.23280 (15)
0.59102 (15)
0.47823 (14)
0.39246 (18)
0.2800 (2)
0.2196
0.3272
0.2992
0.2706 (2)
0.2519 (2)
0.2975
0.2625
0.1505 (2)
0.1419
0.1420
0.0768 (2)
0.1015 (2)
0.0549
0.1871 (2)
0.2032 (2)
0.1479
0.2104
0.2923 (2)
0.3028
0.2830
0.3791 (2)
0.3895
0.3636 (2)
0.3558
0.45342 (19)
0.4435
0.4617
0.5454 (2)
0.5416
0.5997
0.56053 (19)
0.5827 (2)
0.5310
0.6406
0.5904
0.46947 (19)
Uiso*/Ueq
0.0335 (6)
0.0250 (5)
0.0192 (4)
0.0335 (6)
0.0321 (6)
0.0237 (5)
0.0189 (4)
0.0346 (6)
0.0268 (7)
0.040*
0.040*
0.040*
0.0200 (6)
0.0269 (7)
0.032*
0.032*
0.0298 (7)
0.036*
0.036*
0.0256 (7)
0.0236 (7)
0.028*
0.0199 (6)
0.0252 (7)
0.030*
0.030*
0.0233 (7)
0.028*
0.028*
0.0172 (6)
0.021*
0.0171 (6)
0.021*
0.0183 (6)
0.022*
0.022*
0.0174 (6)
0.021*
0.021*
0.0150 (6)
0.0200 (6)
0.030*
0.030*
0.030*
0.0160 (6)
O1
O2
O3
O4
O5
O6
O7
O8
C1
H1A
H1B
H1C
C2
C3
H3A
H3B
C4
H4A
H4B
C5
C6
H6
C7
C8
H8A
H8B
C9
H9A
H9B
C10
H10
C11
H11
C12
H12A
H12B
C13
H13A
H13B
C14
C15
H15A
H15B
H15C
C16