Matricarin

The structure of the sesquiterpene lactone matricarin, C₁₇H₂₀O₂, is composed of a seven-membered ring that adopts a chair conformation, fused to two five-membered rings, one of which is essentially planar and the other exhibits an envelope conformation. The structure is devoid of any classical hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.034
• wR factor = 0.093
• Data-to-parameter ratio = 12.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           30.01
         From the CIF: _reflns_number_total               2477
         Count of symmetry unique reflns         2502
         Completeness (_total/calc)             99.00%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         0
         Fraction of Friedel pairs measured     0.000
         Are heavy atom types Z>Si present           no
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.

---

S1. Comment

We have isolated a sesqiterpene lactone, matricarin, (I), from Achillea vermacularis (Compositae), collected from Tehran area. Martinez et al. (1988) have reported the NMR spectroscopic data for (I) and some related guanianolides without quoting the source of (I). In this paper, we report the structure of (I) which has been established by X-ray crystallographic method.

The structure of (I) is presented in Fig. 1. The molecular dimensions lie within expected values (Orpen et al., 1994) for the corresponding bond distances and angles with mean bond distances: Csp³—Csp³ 1.527 (5), Csp³—Csp² 1.508 (11), Csp²—Csp² 1.480 (16), O—Csp³ 1.455 (2), O—Csp² 1.354 (7), C═C 1.341 (6) and C═O 1.205 (15) Å. The seven-membered ring adopts a chair conformation wherein atoms C5/C6/C8/C9 are in a plane [maximum deviation 0.0096 (8) Å], with C7 0.744 (2) Å above and C1 and C10 1.012 (2) and 1.051 (2) Å, respectively, below this plane. The C1—C5 five-membered ring is essentially planar, with the maximum deviation of any atom being 0.0114 (10) Å. The other five-membered ring, O2/C7/C7/C11/C12, has a C7-envelope conformation with C7 0.608 (3) Å out of the plane of the remaining ring atoms. The structure is devoid of any classical hydrogen bonds.

S2. Experimental

The plants of Achillea vermacularis (Compositae) were collected from Tehran area in July, 1997, shade-dried and ground whole plant material (6 kg) was extracted with methanol. The resulting gummy material (600 g) was partitioned into hexane, ethyl acetate and n-butanol soluble fractions. The ethyl acetate fraction was subjected to column chromatography using hexane/ethyl acetate (7:3) over flash silica which gel afforded (I) as colorless needles suitable XRD analysis.

S3. Refinement

The H atoms were located from difference Fourier synthesis and were included in the refinement at geometrically idealized positions, with C—H distances in the range 0.95–1.00 Å, utilizing riding models and allowing isotropic displacement parameters 1.2 (non-methyl) and 1.5 (methyl) times the equivalent isotropic displacement parameters of the atoms to which they were bonded.

Computing details

Data collection: COLLECT (Hooft, 1998); cell refinement: HKL DENZO (Otwinowski & Minor, 1997); data reduction: SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: TEXSAN (Molecular Structure Corporation, 1994); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

Fig. 1. ORTEPII (Johnson, 1976) drawing of (I) with displacement ellipsoids plotted at the 50% probability level.

(I)

Crystal data

C17H20O5	F(000) = 324
Mr = 304.33	Dx = 1.266 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71069 Å
a = 10.2083 (2) Å	Cell parameters from 2454 reflections
b = 7.5434 (2) Å	θ = 1.0–30.0°
c = 11.0118 (3) Å	µ = 0.09 mm^−1
β = 109.677 (1)°	T = 173 K
V = 798.45 (3) Å^3	Block, colourless
Z = 2	0.25 × 0.20 × 0.18 mm

Data collection

Nonius KappaCCD diffractometer	2477 independent reflections
Radiation source: fine-focus sealed tube	2297 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.016
ω–2ϕ scans	θmax = 30.0°, θmin = 3.3°
Absorption correction: multi-scan (SORTAV: Blessing, 1995, 1997)	h = −14→14
Tmin = 0.977, Tmax = 0.983	k = −10→10
4575 measured reflections	l = −15→15

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.093	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.047P)^2 + 0.087P] where P = (Fo^2 + 2Fc^2)/3
2477 reflections	(Δ/σ)max = 0.003
203 parameters	Δρmax = 0.21 e Å^−3
1 restraint	Δρmin = −0.13 e Å^−3

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

	x	y	z	Uiso*/Ueq
O1	0.40145 (13)	0.18569 (18)	0.29681 (10)	0.0416 (3)
O2	0.41064 (11)	0.28261 (18)	0.81551 (11)	0.0385 (3)
O3	0.44291 (15)	0.3757 (3)	1.01584 (15)	0.0709 (6)
O4	0.88610 (10)	0.22105 (17)	0.88429 (10)	0.0357 (3)
O5	0.99662 (14)	0.3945 (3)	0.78545 (16)	0.0650 (5)
C1	0.50669 (15)	0.1324 (2)	0.52925 (13)	0.0286 (3)
C2	0.39214 (16)	0.1641 (2)	0.40408 (14)	0.0321 (3)
C3	0.26168 (15)	0.1607 (2)	0.43196 (15)	0.0346 (3)
H3	0.1722	0.1748	0.3687	0.042*
C4	0.28403 (15)	0.1353 (2)	0.55720 (15)	0.0323 (3)
C5	0.43934 (14)	0.1164 (2)	0.63346 (13)	0.0278 (3)
H5	0.4585	−0.0035	0.6744	0.033*
C6	0.49748 (14)	0.2601 (2)	0.73539 (14)	0.0289 (3)
H6	0.5011	0.3748	0.6911	0.035*
C7	0.64121 (14)	0.2215 (2)	0.83319 (13)	0.0294 (3)
H7	0.6421	0.0969	0.8645	0.035*
C8	0.75700 (14)	0.2416 (2)	0.77678 (14)	0.0295 (3)
H8	0.7528	0.3610	0.7362	0.035*
C9	0.75161 (15)	0.0953 (2)	0.67924 (15)	0.0330 (3)
H9A	0.8443	0.0850	0.6697	0.040*
H9B	0.7312	−0.0188	0.7136	0.040*
C10	0.64389 (15)	0.1263 (2)	0.54739 (14)	0.0307 (3)
C11	0.64252 (17)	0.3477 (3)	0.94242 (16)	0.0416 (4)
H11	0.6641	0.4702	0.9201	0.050*
C12	0.49165 (19)	0.3396 (3)	0.93434 (18)	0.0464 (4)
C13	0.7393 (2)	0.3019 (5)	1.07851 (18)	0.0672 (8)
H13A	0.7124	0.3708	1.1418	0.101*
H13B	0.8355	0.3304	1.0863	0.101*
H13C	0.7320	0.1751	1.0945	0.101*
C14	0.70502 (18)	0.1503 (3)	0.44187 (16)	0.0383 (4)
H14A	0.6306	0.1782	0.3609	0.058*
H14B	0.7517	0.0407	0.4315	0.058*
H14C	0.7725	0.2476	0.4645	0.058*
C15	0.17222 (15)	0.1207 (3)	0.61644 (18)	0.0434 (4)
H15A	0.0816	0.1087	0.5482	0.065*
H15B	0.1724	0.2274	0.6673	0.065*
H15C	0.1895	0.0163	0.6727	0.065*
C16	0.99833 (16)	0.3077 (3)	0.87667 (18)	0.0396 (4)
C17	1.12117 (17)	0.2786 (4)	0.9959 (2)	0.0574 (6)
H17A	1.2070	0.2955	0.9761	0.086*
H17B	1.1186	0.1577	1.0275	0.086*
H17C	1.1184	0.3636	1.0623	0.086*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0498 (6)	0.0426 (7)	0.0316 (5)	0.0048 (6)	0.0126 (5)	0.0008 (5)
O2	0.0291 (5)	0.0470 (7)	0.0441 (6)	−0.0036 (5)	0.0184 (4)	−0.0123 (5)
O3	0.0523 (8)	0.1082 (16)	0.0624 (9)	−0.0121 (10)	0.0326 (7)	−0.0406 (11)
O4	0.0247 (5)	0.0387 (6)	0.0395 (6)	−0.0043 (4)	0.0055 (4)	−0.0007 (5)
O5	0.0366 (7)	0.0782 (12)	0.0800 (10)	−0.0109 (8)	0.0195 (7)	0.0200 (10)
C1	0.0302 (6)	0.0254 (6)	0.0301 (6)	0.0004 (6)	0.0098 (5)	−0.0011 (6)
C2	0.0370 (7)	0.0251 (7)	0.0324 (7)	0.0016 (6)	0.0093 (5)	−0.0013 (6)
C3	0.0303 (7)	0.0320 (8)	0.0362 (7)	0.0014 (6)	0.0043 (5)	0.0012 (6)
C4	0.0270 (7)	0.0282 (7)	0.0396 (7)	−0.0017 (6)	0.0084 (5)	−0.0004 (6)
C5	0.0258 (6)	0.0260 (7)	0.0310 (6)	−0.0016 (5)	0.0089 (5)	−0.0006 (5)
C6	0.0256 (6)	0.0295 (7)	0.0335 (7)	−0.0014 (6)	0.0125 (5)	−0.0030 (6)
C7	0.0259 (6)	0.0315 (7)	0.0306 (6)	−0.0041 (6)	0.0091 (5)	−0.0035 (6)
C8	0.0230 (6)	0.0303 (7)	0.0340 (7)	−0.0005 (5)	0.0082 (5)	−0.0015 (6)
C9	0.0268 (6)	0.0348 (8)	0.0376 (7)	0.0017 (6)	0.0110 (5)	−0.0033 (6)
C10	0.0328 (7)	0.0265 (7)	0.0350 (7)	−0.0008 (6)	0.0141 (5)	−0.0035 (6)
C11	0.0327 (7)	0.0529 (11)	0.0415 (8)	−0.0090 (7)	0.0154 (6)	−0.0185 (8)
C12	0.0394 (8)	0.0549 (11)	0.0498 (10)	−0.0084 (8)	0.0215 (7)	−0.0197 (9)
C13	0.0495 (10)	0.113 (2)	0.0363 (9)	−0.0085 (13)	0.0101 (8)	−0.0244 (13)
C14	0.0410 (8)	0.0372 (9)	0.0424 (8)	−0.0019 (7)	0.0216 (7)	−0.0035 (7)
C15	0.0275 (7)	0.0532 (11)	0.0486 (9)	−0.0020 (8)	0.0119 (6)	0.0036 (9)
C16	0.0260 (7)	0.0386 (9)	0.0544 (9)	−0.0029 (6)	0.0137 (6)	−0.0057 (8)
C17	0.0269 (8)	0.0598 (13)	0.0730 (13)	−0.0051 (9)	0.0004 (8)	−0.0095 (11)

Geometric parameters (Å, º)

O1—C2	1.2274 (18)	C8—C9	1.528 (2)
O2—C12	1.361 (2)	C8—H8	1.0000
O2—C6	1.4560 (16)	C9—C10	1.516 (2)
O3—C12	1.195 (2)	C9—H9A	0.9900
O4—C16	1.346 (2)	C9—H9B	0.9900
O4—C8	1.4531 (16)	C10—C14	1.503 (2)
O5—C16	1.194 (2)	C11—C12	1.514 (2)
C1—C10	1.347 (2)	C11—C13	1.531 (3)
C1—C2	1.4964 (19)	C11—H11	1.0000
C1—C5	1.5282 (19)	C13—H13A	0.9800
C2—C3	1.464 (2)	C13—H13B	0.9800
C3—C4	1.334 (2)	C13—H13C	0.9800
C3—H3	0.9500	C14—H14A	0.9800
C4—C15	1.497 (2)	C14—H14B	0.9800
C4—C5	1.5305 (19)	C14—H14C	0.9800
C5—C6	1.529 (2)	C15—H15A	0.9800
C5—H5	1.0000	C15—H15B	0.9800
C6—C7	1.5275 (19)	C15—H15C	0.9800
C6—H6	1.0000	C16—C17	1.495 (2)
C7—C8	1.5167 (18)	C17—H17A	0.9800
C7—C11	1.530 (2)	C17—H17B	0.9800
C7—H7	1.0000	C17—H17C	0.9800
C12—O2—C6	108.82 (11)	C8—C9—H9B	108.8
C16—O4—C8	117.07 (13)	H9A—C9—H9B	107.7
C10—C1—C2	126.36 (13)	C1—C10—C14	124.24 (14)
C10—C1—C5	126.45 (12)	C1—C10—C9	122.00 (13)
C2—C1—C5	107.14 (12)	C14—C10—C9	113.76 (12)
O1—C2—C3	125.08 (14)	C12—C11—C13	110.91 (16)
O1—C2—C1	128.17 (14)	C12—C11—C7	100.92 (13)
C3—C2—C1	106.73 (12)	C13—C11—C7	117.44 (19)
C4—C3—C2	111.61 (13)	C12—C11—H11	109.0
C4—C3—H3	124.2	C13—C11—H11	109.0
C2—C3—H3	124.2	C7—C11—H11	109.0
C3—C4—C15	124.82 (14)	O3—C12—O2	121.48 (17)
C3—C4—C5	111.45 (13)	O3—C12—C11	128.28 (18)
C15—C4—C5	123.70 (14)	O2—C12—C11	110.24 (14)
C1—C5—C4	103.03 (11)	C11—C13—H13A	109.5
C1—C5—C6	109.48 (12)	C11—C13—H13B	109.5
C4—C5—C6	114.26 (13)	H13A—C13—H13B	109.5
C1—C5—H5	109.9	C11—C13—H13C	109.5
C4—C5—H5	109.9	H13A—C13—H13C	109.5
C6—C5—H5	109.9	H13B—C13—H13C	109.5
O2—C6—C7	103.37 (11)	C10—C14—H14A	109.5
O2—C6—C5	111.25 (11)	C10—C14—H14B	109.5
C7—C6—C5	115.19 (12)	H14A—C14—H14B	109.5
O2—C6—H6	108.9	C10—C14—H14C	109.5
C7—C6—H6	108.9	H14A—C14—H14C	109.5
C5—C6—H6	108.9	H14B—C14—H14C	109.5
C8—C7—C6	112.84 (12)	C4—C15—H15A	109.5
C8—C7—C11	117.26 (13)	C4—C15—H15B	109.5
C6—C7—C11	100.82 (12)	H15A—C15—H15B	109.5
C8—C7—H7	108.5	C4—C15—H15C	109.5
C6—C7—H7	108.5	H15A—C15—H15C	109.5
C11—C7—H7	108.5	H15B—C15—H15C	109.5
O4—C8—C7	105.89 (11)	O5—C16—O4	123.17 (16)
O4—C8—C9	107.70 (12)	O5—C16—C17	126.12 (17)
C7—C8—C9	111.55 (12)	O4—C16—C17	110.72 (17)
O4—C8—H8	110.5	C16—C17—H17A	109.5
C7—C8—H8	110.5	C16—C17—H17B	109.5
C9—C8—H8	110.5	H17A—C17—H17B	109.5
C10—C9—C8	113.88 (13)	C16—C17—H17C	109.5
C10—C9—H9A	108.8	H17A—C17—H17C	109.5
C8—C9—H9A	108.8	H17B—C17—H17C	109.5
C10—C9—H9B	108.8
C10—C1—C2—O1	1.9 (3)	C16—O4—C8—C7	−150.66 (14)
C5—C1—C2—O1	179.44 (16)	C16—O4—C8—C9	89.89 (16)
C10—C1—C2—C3	−179.45 (16)	C6—C7—C8—O4	173.55 (12)
C5—C1—C2—C3	−1.92 (17)	C11—C7—C8—O4	57.06 (17)
O1—C2—C3—C4	−179.88 (17)	C6—C7—C8—C9	−69.56 (17)
C1—C2—C3—C4	1.43 (19)	C11—C7—C8—C9	173.95 (14)
C2—C3—C4—C15	−178.39 (17)	O4—C8—C9—C10	−164.72 (12)
C2—C3—C4—C5	−0.3 (2)	C7—C8—C9—C10	79.49 (16)
C10—C1—C5—C4	179.21 (16)	C2—C1—C10—C14	−0.3 (3)
C2—C1—C5—C4	1.69 (17)	C5—C1—C10—C14	−177.38 (17)
C10—C1—C5—C6	57.2 (2)	C2—C1—C10—C9	179.25 (16)
C2—C1—C5—C6	−120.27 (13)	C5—C1—C10—C9	2.2 (2)
C3—C4—C5—C1	−0.88 (18)	C8—C9—C10—C1	−63.6 (2)
C15—C4—C5—C1	177.21 (16)	C8—C9—C10—C14	116.04 (15)
C3—C4—C5—C6	117.79 (16)	C8—C7—C11—C12	158.30 (15)
C15—C4—C5—C6	−64.1 (2)	C6—C7—C11—C12	35.41 (17)
C12—O2—C6—C7	26.98 (18)	C8—C7—C11—C13	−81.1 (2)
C12—O2—C6—C5	151.16 (15)	C6—C7—C11—C13	156.06 (17)
C1—C5—C6—O2	164.00 (12)	C6—O2—C12—O3	176.5 (2)
C4—C5—C6—O2	49.05 (17)	C6—O2—C12—C11	−3.5 (2)
C1—C5—C6—C7	−78.81 (15)	C13—C11—C12—O3	33.7 (4)
C4—C5—C6—C7	166.25 (12)	C7—C11—C12—O3	158.9 (3)
O2—C6—C7—C8	−164.56 (12)	C13—C11—C12—O2	−146.3 (2)
C5—C6—C7—C8	73.88 (17)	C7—C11—C12—O2	−21.1 (2)
O2—C6—C7—C11	−38.66 (15)	C8—O4—C16—O5	−2.1 (3)
C5—C6—C7—C11	−160.22 (13)	C8—O4—C16—C17	178.04 (15)