Costuslactone B

The crystal structure of 4,10,11[alpha]-tri­methyl-3-oxocostuslactone, C₁₅H₂₀O₃, a new compound isolated from the dried root of Vladimiria souliei Liarke, has been determined and the compound has been named costuslactone B. The ten-membered ring takes a slightly distorted boat-chair-chair conformation typical of the substituents.

S1. Comment

This work forms part of a series of research on traditional Chinese medicinal herbs aimed at looking for bioactive drugs. The title compound, (I), was extracted from the dried root of Vladimiria Soulilei Liarke, which is widespread in the west of Sichuan province and the south of neighbouring Gansu province. The herb is used for relieving uneasiness and stomach ache in traditional Chinese medicine, and it also has some antitumour function. Similar structures of sesquiterpene lactones have been reported (Breton et al., 1985; Gomez-Rodriguez et al., 1985). \scheme

The conformation of the ten-membered ring of (I) is boat-chair-chair (Fig. 1), and it is slightly distorted owing to the influence of the substituents. The dihedral angles between the planes 1 (C3/C2/C4) and 2 (C1/C2/C4/C5), 2 and 3 (C10/C1/C5/C6), 3 and 4 (C9/C10/C6/C7), and 4 and 5 (C8/C7/C9) are 64.2 (3), 46.2 (1), 63.2 (1) and 62.9 (2)°, respectively. The lactone ring has an envelope conformation.

S2. Experimental

The air-dried, powdered roots of Vladimiria Soulilei Liarke (4.5 kg) were extracted with Et₂O for 7 d. When this Et₂O extract was concentrated, crystals of (I) were precipitated. The experimental sample was recrystallized from ethyl alcohol/acetone mixed solvent.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989?); cell refinement: CAD-4 Software; data reduction: MolEN (Fair, 1990?); program(s) used to solve structure: SHELX97 (Sheldrick, 1997); program(s) used to refine structure: SHELX97; molecular graphics: XP (Siemens, 1994?).

Figures

Fig. 1. A view of (I) showing the labelling of the non-H atoms. Displacement ellipsoids are shown at the 50% probability level and H atoms are drawn as small circles of arbitrary radius.

3,6,10-trimethyl-2,3,3a,4,5,8,9,11a-octahydrocyclodeca[1,2-b]furan-2,9-dione

Crystal data

C15H20O3	Dx = 1.153 Mg m^−3
Mr = 248.31	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 25 reflections
a = 5.553 (1) Å	θ = 10–20°
b = 12.340 (1) Å	µ = 0.08 mm^−1
c = 20.875 (2) Å	T = 293 K
V = 1430.4 (3) Å^3	Block, colourless
Z = 4	0.5 × 0.5 × 0.4 mm
F(000) = 536

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.000
Radiation source: fine-focus sealed tube	θmax = 30.6°, θmin = 1.9°
Graphite monochromator	h = 0→7
ω/2θ scans	k = 0→17
2409 measured reflections	l = 0→29
2409 independent reflections	3 standard reflections every 60 min
2194 reflections with I > 2σ(I)	intensity decay: <0.1%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.031	H-atom parameters constrained
wR(F^2) = 0.137	Calculated w = 1/[σ^2(Fo^2) + (0.0644P)^2 + 0.1316P] where P = (Fo^2 + 2Fc^2)/3
S = 1.24	(Δ/σ)max < 0.001
2409 reflections	Δρmax = 0.14 e Å^−3
164 parameters	Δρmin = −0.14 e Å^−3
0 restraints	Extinction correction: SHELX97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.044 (5)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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.

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

	x	y	z	Uiso*/Ueq
O1	0.1530 (3)	0.98913 (11)	0.84433 (6)	0.0505 (3)
O2	0.2772 (3)	0.84783 (15)	0.90175 (10)	0.0757 (5)
O3	0.0377 (3)	1.24741 (12)	0.72391 (9)	0.0688 (5)
C1	−0.4442 (4)	1.24714 (17)	0.81895 (12)	0.0593 (5)
H1	−0.5488	1.1991	0.8176	0.050*
C2	−0.3663 (5)	1.28685 (17)	0.75380 (11)	0.0622 (5)
H2A	−0.2974	1.3577	0.7565	0.050*
H2B	−0.4707	1.2794	0.7227	0.050*
C3	−0.1630 (4)	1.21412 (16)	0.73249 (9)	0.0519 (4)
C4	−0.2205 (4)	1.09607 (15)	0.72418 (9)	0.0521 (4)
C5	−0.1687 (4)	1.02388 (14)	0.76916 (8)	0.0473 (4)
H5	−0.2065	0.9498	0.7638	0.050*
C6	−0.0679 (3)	1.05086 (13)	0.83384 (8)	0.0441 (4)
H6	−0.0089	1.1234	0.8331	0.050*
C7	−0.2346 (4)	1.02105 (15)	0.89024 (8)	0.0484 (4)
H7	−0.3950	1.0170	0.8743	0.050*
C8	−0.2263 (5)	1.10460 (18)	0.94451 (9)	0.0643 (6)
H8A	−0.2714	1.0756	0.9837	0.050*
H8B	−0.0659	1.1253	0.9490	0.050*
C9	−0.3965 (6)	1.2015 (2)	0.93315 (12)	0.0754 (7)
H9A	−0.3961	1.2469	0.9667	0.050*
H9B	−0.5422	1.1728	0.9253	0.050*
C10	−0.3330 (5)	1.26599 (16)	0.87372 (11)	0.0628 (5)
C11	−0.1430 (4)	0.90767 (18)	0.90837 (10)	0.0556 (5)
H11	−0.2097	0.8596	0.8825	0.050*
C12	0.1170 (4)	0.90783 (17)	0.88695 (10)	0.0555 (5)
C13	−0.1707 (6)	0.8678 (3)	0.97712 (13)	0.0848 (8)
H13A	−0.0702	0.9217	1.0079	0.050*
H13B	−0.1405	0.8021	0.9731	0.050*
H13C	−0.3342	0.8778	0.9918	0.050*
C14	−0.3411 (7)	1.0670 (2)	0.66214 (12)	0.0821 (8)
H14A	−0.3599	0.9873	0.6574	0.050*
H14B	−0.2442	1.0919	0.6331	0.050*
H14C	−0.4931	1.1067	0.6627	0.050*
C15	−0.1267 (7)	1.3428 (2)	0.87983 (15)	0.0811 (8)
H15A	−0.1010	1.3872	0.8482	0.050*
H15B	−0.2049	1.3997	0.9138	0.050*
H15C	−0.0217	1.3136	0.9007	0.050*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0453 (6)	0.0494 (6)	0.0568 (7)	−0.0010 (6)	−0.0020 (6)	0.0064 (6)
O2	0.0613 (9)	0.0761 (10)	0.0898 (12)	0.0113 (9)	−0.0170 (9)	0.0202 (9)
O3	0.0539 (8)	0.0558 (8)	0.0965 (12)	−0.0079 (7)	0.0025 (8)	0.0204 (8)
C1	0.0501 (10)	0.0521 (9)	0.0756 (13)	0.0085 (9)	0.0063 (10)	−0.0023 (9)
C2	0.0628 (12)	0.0512 (9)	0.0726 (12)	0.0036 (10)	−0.0075 (11)	0.0052 (9)
C3	0.0571 (10)	0.0495 (8)	0.0490 (8)	−0.0014 (9)	−0.0071 (8)	0.0124 (7)
C4	0.0592 (11)	0.0498 (8)	0.0474 (8)	−0.0020 (9)	−0.0028 (8)	−0.0015 (7)
C5	0.0540 (9)	0.0397 (7)	0.0482 (8)	−0.0028 (8)	−0.0042 (8)	−0.0048 (6)
C6	0.0489 (9)	0.0357 (6)	0.0478 (8)	−0.0034 (7)	−0.0052 (7)	0.0010 (6)
C7	0.0453 (8)	0.0550 (9)	0.0450 (8)	−0.0044 (8)	−0.0003 (7)	0.0049 (7)
C8	0.0826 (16)	0.0663 (11)	0.0439 (8)	0.0007 (13)	0.0060 (10)	−0.0007 (8)
C9	0.0879 (18)	0.0760 (14)	0.0623 (12)	0.0112 (15)	0.0200 (13)	−0.0122 (11)
C10	0.0660 (13)	0.0487 (9)	0.0737 (12)	0.0108 (10)	0.0103 (11)	−0.0118 (9)
C11	0.0536 (10)	0.0542 (10)	0.0590 (10)	−0.0074 (9)	−0.0075 (9)	0.0122 (8)
C12	0.0578 (11)	0.0527 (9)	0.0559 (9)	−0.0071 (9)	−0.0114 (9)	0.0064 (8)
C13	0.0876 (18)	0.0940 (18)	0.0730 (14)	0.0086 (18)	0.0084 (15)	0.0349 (14)
C14	0.110 (2)	0.0721 (14)	0.0640 (12)	−0.0019 (17)	−0.0298 (15)	0.0013 (11)
C15	0.0899 (19)	0.0623 (12)	0.0912 (18)	−0.0111 (15)	−0.0061 (17)	−0.0061 (13)

Geometric parameters (Å, º)

O1—C12	1.356 (2)	C5—C6	1.499 (2)
O1—C6	1.461 (2)	C6—C7	1.542 (3)
O2—C12	1.198 (3)	C7—C8	1.532 (3)
O3—C3	1.201 (3)	C7—C11	1.536 (3)
C1—C10	1.320 (3)	C8—C9	1.542 (4)
C1—C2	1.509 (3)	C9—C10	1.515 (4)
C2—C3	1.510 (3)	C10—C15	1.493 (4)
C3—C4	1.501 (3)	C11—C12	1.511 (3)
C4—C5	1.326 (3)	C11—C13	1.525 (3)
C4—C14	1.501 (3)
C12—O1—C6	111.12 (15)	C8—C7—C6	112.69 (16)
C10—C1—C2	126.1 (2)	C11—C7—C6	101.92 (16)
C1—C2—C3	106.68 (17)	C7—C8—C9	112.93 (19)
O3—C3—C4	120.8 (2)	C10—C9—C8	113.0 (2)
O3—C3—C2	122.33 (19)	C1—C10—C15	123.0 (2)
C4—C3—C2	116.8 (2)	C1—C10—C9	120.5 (2)
C5—C4—C14	123.20 (19)	C15—C10—C9	116.2 (2)
C5—C4—C3	121.59 (17)	C12—C11—C13	112.0 (2)
C14—C4—C3	115.21 (18)	C12—C11—C7	104.03 (17)
C4—C5—C6	124.73 (15)	C13—C11—C7	119.5 (2)
O1—C6—C5	109.42 (14)	O2—C12—O1	121.1 (2)
O1—C6—C7	105.39 (13)	O2—C12—C11	129.2 (2)
C5—C6—C7	114.25 (15)	O1—C12—C11	109.63 (18)
C8—C7—C11	114.88 (16)