Crystal structure of a bioactive sesquiterpene isolated from Artemisia reticulata

The sesquiterpene mol­ecule has been isolated from Indian herb A. reticulata by column chromatography over silica gel with a mixture of binary solvent ethyl acetate and hexane by gradient elution. It was recrystallized at room temperature by slow evaporation to afford suitable crystal for X-ray diffraction study. Anti­proliferative bioassay of this mol­ecule has been conducted against human ovarian cancer cell line A 2780.

Key indicators

• Single-crystal X-ray study
• T = 299 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.060
• wR factor = 0.164
• Data-to-parameter ratio = 9.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.08 Report
PLAT340_ALERT_3_C Low Bond Precision on  C-C Bonds ...............    0.00463 Ang.

Alert level G
PLAT005_ALERT_5_G No Embedded Refinement Details found  in the CIF     Please Do !
PLAT007_ALERT_5_G Number of Unrefined Donor-H Atoms ..............          1 Report
PLAT008_ALERT_5_G No _iucr_refine_reflections_details   in the CIF     Please Do !
PLAT072_ALERT_2_G SHELXL First  Parameter in WGHT  Unusually Large       0.11 Report
PLAT791_ALERT_4_G The Model has Chirality at C1      (Chiral SPGR)          R Verify
PLAT791_ALERT_4_G The Model has Chirality at C4      (Chiral SPGR)          S Verify
PLAT791_ALERT_4_G The Model has Chirality at C5      (Chiral SPGR)          S Verify
PLAT791_ALERT_4_G The Model has Chirality at C6      (Chiral SPGR)          R Verify
PLAT791_ALERT_4_G The Model has Chirality at C7      (Chiral SPGR)          R Verify
PLAT899_ALERT_4_G SHELXL97   is Deprecated and Succeeded by SHELXL       2014 Note
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) Still          78 %
PLAT978_ALERT_2_G Number C-C Bonds with Positive Residual Density           7 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   2 ALERT level C = Check. Ensure it is not caused by an omission or oversight
  12 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   6 ALERT type 4 Improvement, methodology, query or suggestion
   3 ALERT type 5 Informative message, check

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Computing details

Data collection: CAD-4-PC (Enraf–Nonius, 1993); cell refinement: CAD-4-PC (Enraf–Nonius, 1993); data reduction: REDU4 (Stoe & Cie, 1987); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

1-[6-Hydroxy-7-(propan-2-yl)-4-methylidene-2,3,3a,4,5,6,7,7a-octahydro-1H-inden-1-yl]ethanone

Crystal data

C15H24O2	F(000) = 260
Mr = 236.34	Dx = 1.123 Mg m^−3
Monoclinic, P21	Cu Kα radiation, λ = 1.54180 Å
Hall symbol: P 2yb	Cell parameters from 25 reflections
a = 8.849 (4) Å	θ = 5.5–27.1°
b = 5.336 (1) Å	µ = 0.56 mm^−1
c = 14.994 (5) Å	T = 299 K
β = 99.21 (2)°	Rod, colourless
V = 698.9 (4) Å^3	0.50 × 0.18 × 0.15 mm
Z = 2

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.052
Radiation source: fine-focus sealed tube	θmax = 67.0°, θmin = 3.0°
Graphite monochromator	h = −10→3
ω/2θ scans	k = 0→6
1916 measured reflections	l = −17→17
1392 independent reflections	3 standard reflections every 120 min
1260 reflections with I > 2σ(I)	intensity decay: 1.0%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.164	H-atom parameters constrained
S = 1.10	w = 1/[σ^2(Fo^2) + (0.1147P)^2 + 0.0812P] where P = (Fo^2 + 2Fc^2)/3
1392 reflections	(Δ/σ)max < 0.001
154 parameters	Δρmax = 0.46 e Å^−3
1 restraint	Δρmin = −0.22 e Å^−3

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.

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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.5467 (3)	0.0974 (5)	0.03391 (14)	0.0580 (7)
H1O	0.5259	0.2380	0.0135	0.070*
O2	0.9664 (3)	0.1293 (5)	0.3910 (2)	0.0680 (8)
C1	0.8020 (3)	0.4666 (6)	0.33401 (19)	0.0401 (7)
H1	0.8184	0.6168	0.2992	0.048*
C2	0.7177 (4)	0.5402 (8)	0.4141 (2)	0.0539 (9)
H2A	0.7821	0.5069	0.4715	0.065*
H2B	0.6912	0.7167	0.4112	0.065*
C3	0.5742 (4)	0.3792 (9)	0.4035 (2)	0.0568 (9)
H3A	0.5943	0.2188	0.4335	0.068*
H3B	0.4923	0.4633	0.4277	0.068*
C4	0.5350 (3)	0.3473 (7)	0.3022 (2)	0.0446 (7)
H4	0.5020	0.5109	0.2765	0.053*
C5	0.6918 (3)	0.2887 (5)	0.27514 (17)	0.0355 (6)
H5	0.7191	0.1174	0.2952	0.043*
C6	0.6880 (3)	0.2967 (5)	0.17229 (17)	0.0370 (7)
H6	0.6501	0.4629	0.1518	0.044*
C7	0.5672 (4)	0.1059 (6)	0.13003 (18)	0.0439 (7)
H7	0.6039	−0.0600	0.1517	0.053*
C8	0.4103 (4)	0.1446 (9)	0.1602 (2)	0.0590 (10)
H8A	0.3654	0.2991	0.1341	0.071*
H8B	0.3429	0.0081	0.1371	0.071*
C9	0.4206 (4)	0.1563 (8)	0.2604 (2)	0.0508 (8)
C10	0.9549 (4)	0.3515 (7)	0.3722 (2)	0.0431 (7)
C11	1.0900 (4)	0.5203 (9)	0.3893 (3)	0.0671 (11)
H11A	1.1664	0.4637	0.3552	0.081*
H11B	1.1313	0.5185	0.4526	0.081*
H11C	1.0594	0.6878	0.3713	0.081*
C12	0.8473 (4)	0.2670 (6)	0.1447 (2)	0.0447 (8)
H12	0.9160	0.3774	0.1847	0.054*
C13	0.8571 (5)	0.3509 (9)	0.0487 (2)	0.0604 (10)
H13A	0.8294	0.5246	0.0418	0.072*
H13B	0.7882	0.2524	0.0067	0.072*
H13C	0.9598	0.3286	0.0371	0.072*
C14	0.9125 (5)	0.0040 (8)	0.1601 (3)	0.0613 (10)
H14A	0.8454	−0.1135	0.1251	0.074*
H14B	0.9217	−0.0377	0.2230	0.074*
H14C	1.0116	−0.0027	0.1419	0.074*
C15	0.3418 (5)	0.0067 (11)	0.3076 (3)	0.0708 (12)
H15A	0.2759	−0.1134	0.2780	0.085*
H15B	0.3528	0.0225	0.3701	0.085*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0792 (15)	0.0505 (15)	0.0419 (11)	−0.0110 (14)	0.0024 (10)	−0.0077 (11)
O2	0.0730 (17)	0.0337 (14)	0.0893 (19)	0.0019 (14)	−0.0110 (13)	0.0124 (14)
C1	0.0543 (16)	0.0251 (14)	0.0392 (13)	−0.0004 (13)	0.0022 (12)	0.0020 (12)
C2	0.067 (2)	0.045 (2)	0.0479 (16)	0.0059 (17)	0.0046 (14)	−0.0101 (16)
C3	0.0614 (19)	0.063 (2)	0.0489 (17)	0.0040 (18)	0.0176 (14)	−0.0047 (18)
C4	0.0501 (16)	0.0376 (17)	0.0472 (16)	0.0042 (15)	0.0112 (12)	−0.0022 (14)
C5	0.0451 (14)	0.0226 (14)	0.0386 (14)	−0.0002 (12)	0.0059 (11)	0.0015 (12)
C6	0.0513 (16)	0.0226 (14)	0.0369 (13)	0.0002 (13)	0.0064 (11)	0.0013 (12)
C7	0.0570 (17)	0.0330 (17)	0.0410 (14)	−0.0066 (15)	0.0052 (13)	−0.0001 (14)
C8	0.0527 (18)	0.062 (3)	0.0603 (19)	−0.010 (2)	0.0022 (14)	−0.004 (2)
C9	0.0423 (15)	0.049 (2)	0.0626 (18)	−0.0012 (16)	0.0135 (13)	−0.0002 (17)
C10	0.0516 (17)	0.0324 (16)	0.0438 (15)	−0.0007 (14)	0.0026 (12)	−0.0008 (14)
C11	0.0541 (19)	0.047 (2)	0.095 (3)	−0.0055 (18)	−0.0023 (18)	−0.002 (2)
C12	0.0551 (17)	0.0307 (16)	0.0492 (17)	−0.0035 (15)	0.0108 (13)	−0.0007 (14)
C13	0.078 (2)	0.052 (2)	0.0559 (19)	−0.004 (2)	0.0248 (17)	−0.0006 (18)
C14	0.070 (2)	0.042 (2)	0.077 (2)	0.0144 (19)	0.0264 (18)	0.0068 (19)
C15	0.060 (2)	0.076 (3)	0.080 (2)	−0.014 (2)	0.0229 (18)	−0.004 (2)

Geometric parameters (Å, º)

O1—C7	1.424 (3)	C7—C8	1.542 (5)
O1—H1O	0.8200	C7—H7	0.9800
O2—C10	1.219 (5)	C8—C9	1.493 (5)
C1—C10	1.513 (4)	C8—H8A	0.9700
C1—C5	1.535 (4)	C8—H8B	0.9700
C1—C2	1.562 (5)	C9—C15	1.335 (6)
C1—H1	0.9800	C10—C11	1.486 (5)
C2—C3	1.521 (6)	C11—H11A	0.9600
C2—H2A	0.9700	C11—H11B	0.9600
C2—H2B	0.9700	C11—H11C	0.9600
C3—C4	1.513 (4)	C12—C14	1.521 (5)
C3—H3A	0.9700	C12—C13	1.523 (5)
C3—H3B	0.9700	C12—H12	0.9800
C4—C9	1.501 (5)	C13—H13A	0.9600
C4—C5	1.539 (4)	C13—H13B	0.9600
C4—H4	0.9800	C13—H13C	0.9600
C5—C6	1.538 (3)	C14—H14A	0.9600
C5—H5	0.9800	C14—H14B	0.9600
C6—C7	1.537 (4)	C14—H14C	0.9600
C6—C12	1.540 (4)	C15—H15A	0.9300
C6—H6	0.9800	C15—H15B	0.9300
C7—O1—H1O	109.5	C6—C7—H7	106.8
C10—C1—C5	114.5 (3)	C8—C7—H7	106.8
C10—C1—C2	108.6 (2)	C9—C8—C7	112.9 (3)
C5—C1—C2	105.1 (2)	C9—C8—H8A	109.0
C10—C1—H1	109.5	C7—C8—H8A	109.0
C5—C1—H1	109.5	C9—C8—H8B	109.0
C2—C1—H1	109.5	C7—C8—H8B	109.0
C3—C2—C1	105.8 (3)	H8A—C8—H8B	107.8
C3—C2—H2A	110.6	C15—C9—C8	123.8 (4)
C1—C2—H2A	110.6	C15—C9—C4	124.0 (4)
C3—C2—H2B	110.6	C8—C9—C4	112.2 (3)
C1—C2—H2B	110.6	O2—C10—C11	121.0 (3)
H2A—C2—H2B	108.7	O2—C10—C1	121.3 (3)
C4—C3—C2	102.8 (3)	C11—C10—C1	117.7 (3)
C4—C3—H3A	111.2	C10—C11—H11A	109.5
C2—C3—H3A	111.2	C10—C11—H11B	109.5
C4—C3—H3B	111.2	H11A—C11—H11B	109.5
C2—C3—H3B	111.2	C10—C11—H11C	109.5
H3A—C3—H3B	109.1	H11A—C11—H11C	109.5
C9—C4—C3	121.8 (3)	H11B—C11—H11C	109.5
C9—C4—C5	109.2 (3)	C14—C12—C13	109.7 (3)
C3—C4—C5	102.5 (2)	C14—C12—C6	113.3 (3)
C9—C4—H4	107.5	C13—C12—C6	114.6 (3)
C3—C4—H4	107.5	C14—C12—H12	106.2
C5—C4—H4	107.5	C13—C12—H12	106.2
C1—C5—C6	118.0 (2)	C6—C12—H12	106.2
C1—C5—C4	103.8 (2)	C12—C13—H13A	109.5
C6—C5—C4	112.5 (2)	C12—C13—H13B	109.5
C1—C5—H5	107.3	H13A—C13—H13B	109.5
C6—C5—H5	107.3	C12—C13—H13C	109.5
C4—C5—H5	107.3	H13A—C13—H13C	109.5
C7—C6—C5	107.3 (2)	H13B—C13—H13C	109.5
C7—C6—C12	115.3 (3)	C12—C14—H14A	109.5
C5—C6—C12	113.1 (2)	C12—C14—H14B	109.5
C7—C6—H6	106.9	H14A—C14—H14B	109.5
C5—C6—H6	106.9	C12—C14—H14C	109.5
C12—C6—H6	106.9	H14A—C14—H14C	109.5
O1—C7—C6	113.9 (2)	H14B—C14—H14C	109.5
O1—C7—C8	109.0 (2)	C9—C15—H15A	120.0
C6—C7—C8	112.9 (3)	C9—C15—H15B	120.0
O1—C7—H7	106.8	H15A—C15—H15B	120.0
C10—C1—C2—C3	−116.4 (3)	C5—C6—C7—C8	52.9 (3)
C5—C1—C2—C3	6.5 (4)	C12—C6—C7—C8	179.9 (3)
C1—C2—C3—C4	−31.5 (4)	O1—C7—C8—C9	−179.9 (3)
C2—C3—C4—C9	166.7 (3)	C6—C7—C8—C9	−52.2 (4)
C2—C3—C4—C5	44.5 (4)	C7—C8—C9—C15	−124.2 (4)
C10—C1—C5—C6	−95.1 (3)	C7—C8—C9—C4	53.1 (4)
C2—C1—C5—C6	145.9 (3)	C3—C4—C9—C15	2.1 (6)
C10—C1—C5—C4	139.6 (3)	C5—C4—C9—C15	121.1 (4)
C2—C1—C5—C4	20.5 (3)	C3—C4—C9—C8	−175.3 (3)
C9—C4—C5—C1	−170.9 (3)	C5—C4—C9—C8	−56.3 (4)
C3—C4—C5—C1	−40.5 (3)	C5—C1—C10—O2	−31.7 (5)
C9—C4—C5—C6	60.4 (3)	C2—C1—C10—O2	85.3 (4)
C3—C4—C5—C6	−169.2 (3)	C5—C1—C10—C11	150.5 (3)
C1—C5—C6—C7	−179.0 (3)	C2—C1—C10—C11	−92.5 (4)
C4—C5—C6—C7	−58.0 (3)	C7—C6—C12—C14	−53.3 (4)
C1—C5—C6—C12	52.8 (3)	C5—C6—C12—C14	70.7 (4)
C4—C5—C6—C12	173.7 (3)	C7—C6—C12—C13	73.6 (4)
C5—C6—C7—O1	178.0 (2)	C5—C6—C12—C13	−162.4 (3)
C12—C6—C7—O1	−55.0 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···O1^i	0.82	2.11	2.927 (4)	175
C11—H11C···O2^ii	0.96	2.53	3.430 (6)	157

Symmetry codes: (i) −x+1, y+1/2, −z; (ii) x, y+1, z.