Crystal structure of pseudoguainolide

The lactone ring in the title mol­ecule, C₁₅H₂₂O₃ (systematic name: 3,4a,8-tri­methyl­dodeca­hydro­azuleno[6,5-b]furan-2,5-dione), assumes an envelope conformation with the methine C atom adjacent to the the methine C atom carrying the methyl substituent being the flap atom. The other five-membered ring adopts a twisted conformation with the twist being about the methine–methyl­ene C—C bond. The seven-membered ring is based on a twisted boat conformation. No specific inter­actions are noted in the the crystal packing.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.047
• wR factor = 0.107
• Data-to-parameter ratio = 18.7

checkCIF/PLATON results

No syntax errors found



Alert level C
STRVA01_ALERT_4_C           Flack test results are meaningless.
           From the CIF: _refine_ls_abs_structure_Flack    0.100
           From the CIF: _refine_ls_abs_structure_Flack_su    1.300
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O1     --  C1      ..        5.1 su
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          4 Report
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          4 Note

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT032_ALERT_4_G Std. Uncertainty on Flack Parameter Value High .      1.300 Report
PLAT066_ALERT_1_G Predicted and Reported Tmin&Tmax Range Identical          ? Check
PLAT791_ALERT_4_G The Model has Chirality at C2      (Chiral SPGR)          S Verify
PLAT791_ALERT_4_G The Model has Chirality at C3      (Chiral SPGR)          S Verify
PLAT791_ALERT_4_G The Model has Chirality at C4      (Chiral SPGR)          R 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
PLAT791_ALERT_4_G The Model has Chirality at C8      (Chiral SPGR)          S Verify
PLAT899_ALERT_4_G SHELXL97   is Deprecated and Succeeded by SHELXL       2014 Note
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Th(Min) ...          2 Report
PLAT916_ALERT_2_G Hooft y and Flack x Parameter values differ by .       1.30 Check

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   4 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

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

---

S1. Comment

Inula graveolens have consistently been the subject of research interest (Chiappini & Fardella, 1980; Rustaiyan et al., 1987). Our interest is in the extracts from aerial parts of Algerian species such as stems, flowers and leaves. The asymmetric unit of the crystal structure consists of a single molecule (Fig. 1). In the molecule, the lactone ring assumes an envelope conformation. In the crystal structure, the planes of the lactone rings are approximately parallel. The molecules are arranged with the lactone rings stacked parallel to the a axis. Structures of some related compounds have been reported (Herz et al., 1982; Schmidt et al., 1996; Wu et al., 2012; Billodeaux et al., 2014).

Related literature

For background to inula graveolens, see: Chiappini & Fardella (1980); Rustaiyan et al. (1987). For related structures, see: Herz et al. (1982); Schmidt et al. (1996); Wu et al. (2012); Billodeaux et al. (2014).

S2. Experimental

The air-dried aerial parts of inula graveolens (500 g) were extracted with acetone/Et₂O (1:1) at room temperature. The solution was filtered off and concentrated under reduced pressure to give a pale-yellow gum (9 g). The gum was subjected to successive column chromatography (silica gel) and TLC (silica gel, PF254). Eleven fractions were obtained. Fraction 5 gave a material which crystallized as colourless crystals with a melting point of 152 ^oC.

S3. Refinement

Carbon-bound H-atoms were placed in calculated positions (C—H = 0.96–0.98 Å) and were included in the refinement in the riding model approximation, with U_iso(H) set to 1.2–1.5U_equiv(C).

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures

Fig. 1. A molecule showing atom labels and 50% probability displacement ellipsoids for non-H atoms.

3,4a,8-Trimethyldodecahydroazuleno[6,5-b]furan-2,5-dione

Crystal data

C15H22O3	Dx = 1.225 Mg m^−3
Mr = 250.33	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 3098 reflections
a = 7.4320 (3) Å	θ = 3.1–27.5°
b = 11.9278 (3) Å	µ = 0.08 mm^−1
c = 15.3152 (6) Å	T = 150 K
V = 1357.65 (8) Å^3	Plate, colourless
Z = 4	0.20 × 0.20 × 0.04 mm
F(000) = 544

Data collection

Nonius KappaCCD diffractometer	3098 independent reflections
Radiation source: fine-focus sealed tube	2533 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.041
CCD slices, ω and ϕ scans	θmax = 27.5°, θmin = 3.1°
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997)	h = −9→9
Tmin = 0.984, Tmax = 0.997	k = −15→15
9382 measured reflections	l = −19→17

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.107	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0453P)^2 + 0.2031P] where P = (Fo^2 + 2Fc^2)/3
3098 reflections	(Δ/σ)max < 0.001
166 parameters	Δρmax = 0.15 e Å^−3
0 restraints	Δρmin = −0.16 e Å^−3

Special details

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 > 2σ(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
C1	0.8136 (2)	0.24699 (16)	0.52812 (12)	0.0383 (4)
C2	0.8423 (3)	0.16380 (15)	0.45546 (12)	0.0407 (4)
H2	0.9722	0.1503	0.4522	0.049*
C3	0.7918 (2)	0.22980 (13)	0.37360 (11)	0.0318 (4)
H3	0.6620	0.2220	0.3642	0.038*
C4	0.8307 (2)	0.35109 (14)	0.40005 (11)	0.0338 (4)
H4	0.9552	0.3703	0.3852	0.041*
C5	0.8884 (2)	0.19024 (14)	0.29170 (12)	0.0346 (4)
H5A	0.8386	0.1183	0.2748	0.041*
H5B	1.0142	0.1785	0.3060	0.041*
C6	0.8781 (2)	0.26974 (15)	0.21218 (12)	0.0371 (4)
C7	0.7099 (3)	0.34762 (15)	0.20872 (12)	0.0388 (4)
H7	0.6065	0.3039	0.2292	0.047*
C8	0.7176 (3)	0.45618 (14)	0.26350 (13)	0.0429 (5)
H8	0.8326	0.4932	0.2513	0.052*
C9	0.7050 (3)	0.43722 (14)	0.36244 (12)	0.0396 (4)
H9A	0.7276	0.5081	0.3914	0.048*
H9B	0.5827	0.4152	0.3763	0.048*
C10	0.8618 (3)	0.20169 (18)	0.12824 (14)	0.0495 (5)
C11	0.7283 (4)	0.25562 (19)	0.06728 (14)	0.0630 (6)
H11A	0.6211	0.2099	0.0617	0.076*
H11B	0.7805	0.2665	0.0098	0.076*
C12	0.6842 (3)	0.36830 (18)	0.10993 (14)	0.0583 (6)
H12A	0.5613	0.3905	0.0973	0.070*
H12B	0.7651	0.4264	0.0893	0.070*
C13	0.7564 (3)	0.05319 (14)	0.47094 (13)	0.0453 (5)
H13A	0.6282	0.0623	0.4737	0.068*
H13B	0.7992	0.0226	0.5251	0.068*
H13C	0.7864	0.0032	0.4240	0.068*
C14	1.0567 (3)	0.33493 (19)	0.20250 (15)	0.0519 (5)
H14A	1.0488	0.3846	0.1533	0.078*
H14B	1.1536	0.2830	0.1937	0.078*
H14C	1.0786	0.3777	0.2545	0.078*
C15	0.5664 (3)	0.53701 (18)	0.23775 (17)	0.0650 (7)
H15A	0.5670	0.6004	0.2764	0.098*
H15B	0.4526	0.4992	0.2419	0.098*
H15C	0.5847	0.5620	0.1788	0.098*
O1	0.79726 (18)	0.22938 (12)	0.60507 (9)	0.0478 (3)
O2	0.80792 (16)	0.35200 (10)	0.49559 (7)	0.0390 (3)
O3	0.9465 (2)	0.11791 (15)	0.11224 (11)	0.0721 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0265 (8)	0.0451 (10)	0.0433 (11)	−0.0014 (8)	−0.0003 (8)	0.0008 (8)
C2	0.0416 (10)	0.0404 (9)	0.0400 (10)	−0.0014 (8)	0.0015 (8)	0.0040 (8)
C3	0.0265 (8)	0.0298 (8)	0.0392 (9)	−0.0018 (7)	0.0004 (7)	0.0008 (7)
C4	0.0296 (9)	0.0335 (8)	0.0384 (9)	−0.0040 (7)	0.0040 (7)	−0.0020 (7)
C5	0.0314 (9)	0.0331 (9)	0.0393 (10)	0.0025 (7)	−0.0013 (8)	−0.0011 (7)
C6	0.0344 (9)	0.0381 (9)	0.0387 (10)	−0.0011 (8)	0.0020 (8)	0.0015 (8)
C7	0.0381 (9)	0.0357 (8)	0.0426 (10)	0.0007 (8)	−0.0058 (8)	0.0050 (8)
C8	0.0453 (11)	0.0301 (8)	0.0534 (12)	0.0008 (9)	0.0005 (9)	0.0064 (8)
C9	0.0373 (10)	0.0303 (8)	0.0512 (11)	−0.0012 (8)	0.0023 (9)	−0.0031 (7)
C10	0.0526 (12)	0.0532 (12)	0.0426 (12)	0.0015 (10)	−0.0019 (9)	−0.0027 (9)
C11	0.0807 (17)	0.0660 (14)	0.0424 (12)	0.0121 (14)	−0.0134 (12)	−0.0037 (10)
C12	0.0731 (15)	0.0544 (12)	0.0472 (12)	0.0092 (12)	−0.0115 (12)	0.0079 (9)
C13	0.0473 (11)	0.0383 (10)	0.0502 (12)	0.0076 (9)	0.0064 (9)	0.0056 (8)
C14	0.0441 (11)	0.0595 (12)	0.0522 (13)	−0.0096 (10)	0.0101 (10)	0.0073 (10)
C15	0.0772 (17)	0.0419 (11)	0.0761 (17)	0.0178 (12)	−0.0123 (14)	0.0068 (11)
O1	0.0432 (8)	0.0636 (8)	0.0367 (8)	−0.0003 (7)	0.0028 (6)	0.0023 (6)
O2	0.0380 (7)	0.0401 (7)	0.0388 (7)	−0.0038 (6)	0.0016 (6)	−0.0055 (5)
O3	0.0840 (12)	0.0763 (11)	0.0560 (10)	0.0307 (10)	−0.0134 (9)	−0.0248 (9)

Geometric parameters (Å, º)

C1—O1	1.203 (2)	C8—C15	1.532 (3)
C1—O2	1.349 (2)	C8—C9	1.535 (3)
C1—C2	1.506 (3)	C8—H8	0.9800
C2—C13	1.485 (2)	C9—H9A	0.9700
C2—C3	1.527 (2)	C9—H9B	0.9700
C2—H2	0.9800	C10—O3	1.206 (2)
C3—C5	1.520 (2)	C10—C11	1.507 (3)
C3—C4	1.530 (2)	C11—C12	1.530 (3)
C3—H3	0.9800	C11—H11A	0.9700
C4—O2	1.473 (2)	C11—H11B	0.9700
C4—C9	1.503 (2)	C12—H12A	0.9700
C4—H4	0.9800	C12—H12B	0.9700
C5—C6	1.545 (3)	C13—H13A	0.9600
C5—H5A	0.9700	C13—H13B	0.9600
C5—H5B	0.9700	C13—H13C	0.9600
C6—C10	1.525 (3)	C14—H14A	0.9600
C6—C14	1.546 (3)	C14—H14B	0.9600
C6—C7	1.558 (3)	C14—H14C	0.9600
C7—C8	1.544 (3)	C15—H15A	0.9600
C7—C12	1.545 (3)	C15—H15B	0.9600
C7—H7	0.9800	C15—H15C	0.9600
O1—C1—O2	121.39 (17)	C9—C8—H8	107.9
O1—C1—C2	128.53 (18)	C7—C8—H8	107.9
O2—C1—C2	110.08 (15)	C4—C9—C8	116.18 (15)
C13—C2—C1	114.00 (15)	C4—C9—H9A	108.2
C13—C2—C3	118.92 (16)	C8—C9—H9A	108.2
C1—C2—C3	103.43 (14)	C4—C9—H9B	108.2
C13—C2—H2	106.6	C8—C9—H9B	108.2
C1—C2—H2	106.6	H9A—C9—H9B	107.4
C3—C2—H2	106.6	O3—C10—C11	124.8 (2)
C5—C3—C2	113.67 (14)	O3—C10—C6	124.83 (19)
C5—C3—C4	115.01 (14)	C11—C10—C6	110.31 (17)
C2—C3—C4	102.93 (13)	C10—C11—C12	104.58 (18)
C5—C3—H3	108.3	C10—C11—H11A	110.8
C2—C3—H3	108.3	C12—C11—H11A	110.8
C4—C3—H3	108.3	C10—C11—H11B	110.8
O2—C4—C9	107.71 (13)	C12—C11—H11B	110.8
O2—C4—C3	104.38 (13)	H11A—C11—H11B	108.9
C9—C4—C3	115.32 (15)	C11—C12—C7	104.55 (16)
O2—C4—H4	109.7	C11—C12—H12A	110.8
C9—C4—H4	109.7	C7—C12—H12A	110.8
C3—C4—H4	109.7	C11—C12—H12B	110.8
C3—C5—C6	115.87 (13)	C7—C12—H12B	110.8
C3—C5—H5A	108.3	H12A—C12—H12B	108.9
C6—C5—H5A	108.3	C2—C13—H13A	109.5
C3—C5—H5B	108.3	C2—C13—H13B	109.5
C6—C5—H5B	108.3	H13A—C13—H13B	109.5
H5A—C5—H5B	107.4	C2—C13—H13C	109.5
C10—C6—C5	109.98 (14)	H13A—C13—H13C	109.5
C10—C6—C14	104.76 (16)	H13B—C13—H13C	109.5
C5—C6—C14	109.96 (15)	C6—C14—H14A	109.5
C10—C6—C7	103.01 (15)	C6—C14—H14B	109.5
C5—C6—C7	115.63 (14)	H14A—C14—H14B	109.5
C14—C6—C7	112.70 (14)	C6—C14—H14C	109.5
C8—C7—C12	113.76 (15)	H14A—C14—H14C	109.5
C8—C7—C6	116.85 (15)	H14B—C14—H14C	109.5
C12—C7—C6	103.16 (15)	C8—C15—H15A	109.5
C8—C7—H7	107.5	C8—C15—H15B	109.5
C12—C7—H7	107.5	H15A—C15—H15B	109.5
C6—C7—H7	107.5	C8—C15—H15C	109.5
C15—C8—C9	107.59 (17)	H15A—C15—H15C	109.5
C15—C8—C7	111.13 (17)	H15B—C15—H15C	109.5
C9—C8—C7	114.24 (14)	C1—O2—C4	110.89 (13)
C15—C8—H8	107.9