(3R,4S,5S,8S,10R,13R)-3-Hy­droxy­kaura-9(11),16-dien-18-oic acid

Beattie, K.D.; Bhadbhade, M.M.; Craig, D.C.; Leach, D.N.

doi:10.1107/S1600536812002206

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 68| Part 2| February 2012| Pages o526-o527

doi:10.1107/S1600536812002206

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(3R,4S,5S,8S,10R,13R)-3-Hydroxykaura-9(11),16-dien-18-oic acid

Karren D. Beattie,^a ^* Mohan M. Bhadbhade,^b Donald C. Craig ^b and David N. Leach ^a

^aCentre for Phytochemistry and Pharmacology, Southern Cross University, Lismore Campus, NSW 2480, Australia, and ^bSchool of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
^*Correspondence e-mail: karren.beattie@hotmail.com

(Received 19 September 2011; accepted 18 January 2012; online 25 January 2012)

The title compound, C₂₀H₂₈O₃, was isolated during our investigation into the chemical composition and pharmacological activity of Centipeda cunninghamii (DC.) A. Braun & Asch. (Asteraceae). The enantiopure compound, a diterpene with a carbon skeleton, is composed of three six- and one five-membered rings in chair, twist-boat, half-chair and envelope conformations, respectively. Each molecule makes one intra- and one intermolecular O—H⋯O hydrogen bond in the crystal lattice, forming hydrogen-bonded chains along [010]. The absolute configuration of the compound was assigned on the basis of optical rotation measurements.

Related literature

For the characterization of related kaurane diterpenes, see: Reynolds et al. (1991 ); Piozzi et al. (1972 ). For literature on the occurrence of the 3S isomer of the title compound isolated from Ichthyothere terminalis and Pseudognaphalium cheiranthifolium, see: Bohlmann et al. (1982 ); Mendoza & Urzúa (1998 ). For the antibacterial activity of the 3S isomer, see: Mendoza et al. (1997 ). For phytopharmacological aspects of Centipeda cunninghamii, see: Campbell (1973 ); Cribb (1988 ); D'Amelio & Mirhom, (1998 ); Maiden (1975 ); Webb (1948 ). For optical rotation data of related compounds, see: Bohlmann et al. (1982); Brieskorn & Pöhlmann (1968 ); Reynolds et al. (1991).

Experimental

Crystal data

C₂₀H₂₈O₃
M_r = 316.4
Monoclinic, P 2₁
a = 8.064 (2) Å
b = 10.775 (3) Å
c = 10.462 (4) Å
β = 109.70 (2)°
V = 855.8 (5) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.30 × 0.25 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
1586 measured reflections
1586 independent reflections
1254 reflections with I > 2σ(I)
R_int = 0.000
1 standard reflections every 30 min intensity decay: none

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.112
S = 1.05
1586 reflections
218 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.15 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1O3⋯O1ⁱ	0.82 (5)	1.83 (5)	2.637 (4)	169 (5)
O1—H1O1⋯O2	0.96 (7)	1.94 (6)	2.651 (4)	129 (5)
Symmetry code: (i) $[-x+1, y-{\script{1\over 2}}, -z+2]$ .

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ) and Mercury (Macrae et al., 2008 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812002206/qk2025sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812002206/qk2025Isup2.hkl

checkCIF report

Comment top

The title compound C₂₀H₂₈O₃ [Fig. 1., systematic name (3R,4S,5S,8S,10R,13R)-3-hydroxykaura-9(11),16-dien-18-oic acid], a diterpene, was isolated during our investigation into the chemical composition and pharmacological activity of active components of Centipeda cunninghamii. The herb is native to Australia and New Zealand and has been utilized by the Aboriginals to treat infection (Campbell, 1973; Cribb, 1988; D'Amelio & Mirhom, 1998) and inflammation (Maiden, 1975; Webb, 1948). Compound (I) crystallizes in the monoclinic chiral space group P2₁. The carbon skeleton is composed of three six- and one five-membered rings in chair (ring A), twist-boat (ring B), half-chair (ring C) and envelope conformations (ring D). In the unit cell, two symmetry equivalent molecules make an intramolecular O—H···O bond between the 3-OH (O1) and the carbonyl oxygen (O2) and are linked by intermolecular O—H···O hydrogen bonds involving the carboxylic hydroxyl group (O3, donor) and the 3-OH group (O1, acceptor) into infinite chains extending parallel to the b axis (Fig. 2; Table 1).

The majority of the ent-kaurane diterpenes characteristically exhibit negative values for optical rotation with the exception of those that feature a double bond between C9 and C11. Piozzi and co-workers (Piozzi et al., 1972) have demonstrated that sequential catalytic hydrogenation of the exocyclic C16—C17 and the endocyclic C9—C11 double bonds in grandiflorenic acid [(4α)-kaura-9(11),16-dien-18-oic acid] transforms the optical rotation from +38 to +43° and subsequently to -80° in the saturated product. More recently Reynolds and co-workers (Reynolds et al., 1991) have analysed the solid state and solution characteristics of grandiflorenic acid, and have determined that the introduction of the C9—C11 double bond in grandiflorenic acid has a drastic effect on the molecular conformation and consequently on optical rotation, whereby the B ring adopts a boat conformation compared to the regular chair conformation in kaurenoic acid. In the case of compound (I) the observed rotation is [α]_D²² + 30.8° (c 0.12, MeOH), which is in agreement with values for the methyl ester derivative of the 3S isomer, +15° (Bohlmann et al., 1982) and the closely related grandiflorenic acid +32.1° (Brieskorn & Pöhlmann, 1968) and + 46° (Reynolds et al., 1991) and establishes the 3R,4S,5S,8S,10R,13R absolute stereochemistry of compound (I). The 3S isomer of compound (I) has been obtained previously from Ichthyothere terminalis (Bohlmann et al., 1982) and Pseudognaphalium cheiranthifolium (Mendoza & Urzúa, 1998). The antibacterial activity of the 3S isomer has also been evaluated and is described in Mendoza et al. (1997).

Related literature top

For the characterization of related kaurane diterpenes, see: Reynolds et al. (1991); Piozzi et al. (1972). For literature on the occurrence of the 3S isomer of the title compound isolated from Ichthyothere terminalis and Pseudognaphalium cheiranthifolium, see: Bohlmann et al. (1982); Mendoza & Urzúa (1998). For the antibacterial activity of the 3S isomer, see: Mendoza et al. (1997). For phytopharmacological aspects of Centipeda cunninghamii, see: Campbell (1973); Cribb (1988); D'Amelio & Mirhom, (1998); Maiden (1975); Webb (1948). For optical rotation data of related compounds, see: Bohlmann et al. (1982); Brieskorn & Pöhlmann (1968); Reynolds et al. (1991).

Experimental top

The whole, air-dried flowers of Centipeda cunninghamii (100 g) were extracted in 100% ethanol (1 L) overnight at ambient temperatures with stirring. The resulting extract was filtered and then partitioned with hexane (3 × 200 ml). The hexane soluble fraction (2.8 g, 2.8% yield w/w) was evaporated and then subjected to reverse phase preparative HPLC (Gilson preparative HPLC system; Phenomenex Luna C18 column, 5 µm, 50 mm × 21.2 mm; sample loading 50 - 100 mg/injection). The column was eluted using a stepwise gradient of H₂O/CH₃CN containing 0.05% CF₃COOH (3:2 to 1:3 over 16.4 min; 1:3 isocratic for 3.6 min; then 1:3 to 1:9 over 1.0 min; then 1:9 isocratic for 7 minutes) at a flow rate of 15 ml/min. Crystals suitable for X-ray diffraction were obtained by slow evaporation of the H₂O/CH₃CN HPLC eluent of (I).

(3R,4S,5S,8S,10R,13R)- 3-Hydroxykaura-9(11),16-dien-18-oic acid (I): Colourless needles (ACN/H₂O) (26.5 mg, 1.0% yield w/w, not optimized); [α]_D²² + 30.8° (c 0.12, MeOH); ¹H NMR (500 MHz, CD₃OD): δ 5.26 (1H, t, J = 3.3 Hz, H-11), 4.89 (1H, d, J = 1.1 Hz, H-17a), 4.77 (1H, br s, H-17b), 3.17 (1H, dd, J = 4.4, 12.1 Hz, H-3), 2.74 (1H, br s, H-13), 2.61 (1H, br d, J = 14.8 Hz, H-15a), 2.44 - 2.40 (1H, m, H-12a), 2.41 - 2.35 (1H, m, H-6a), 2.29 - 2.16 (1H, m, H-2a), 2.20 - 2.16 (1H, m, H-15b), 2.04 (1H, m, H-1a), 1.99 - 1.95 (1H, m. H-7a), 1.99 - 1.95 (1H, m, H-12b), 1.93 – 1.85 (1H, m, H-6 b), 1.68 - 1.74 (1H, m, H-2 b), 1.65 – 1.62 (1H, m, H-5), 1.63 - 1.60 (1H, m, H-14a), 1.51 - 1.47 (1H, m, H-7 b), 1.51 - 1.47 (1H, m, H-14b), 1.38 - 1.32 (1H, m, H-1 b), 1.36 (3H, s, H-19), 1.10 (3H, s, H-20); Lit. (3S isomer as the methyl ester derivative, see Bohlmann et al., 1982); ¹³C NMR (126 MHz, CD₃OD): δ 180.1 (C, C-18), 159.6 (C, C-16), 157.3 (C, C-9), 116.3 (CH, C-11), 106.2 (CH₂, C-17), 79.4 (CH, C-3), 51.5 (CH₂, C-15), 51.3 (C, C-4), 47.0 (CH, C-5), 46.2 (CH₂, C-14), 43.6 (C, C-8), 42.8 (CH, C-13), 40.4 (CH₂, C-1), 39.7 (C, C-10), 39.1 (CH₂, C-12), 31.0 (CH₂, C-7), 29.9 (CH₂, C-2), 24.6 (CH₃, C-19), 24.4 (CH₃, C-20), 19.8 (CH₂, C-6); (+)-LRAPCIMS m/z (rel. int.): 316 [M+H⁺, 0%], 299 (100), 271 (59), 253 (93), 225 (6); (+)-HRAPCIMS m/z (rel. int): 317.2109 calcd for C₂₀H₂₉O₃, 317.2118 (Δ0.0009 a.m.u.).

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: CAD-4 Software (Enraf–Nonius, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. View of (I) with atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 40% probability level.
	Fig. 2. Packing diagram of (I) viewed down the a axis depicting intra and inter molecular O—H···O hydrogen bonding.

(3R,4S,5S,8S,10R,13R)- 3-Hydroxykaura-9(11),16-dien-18-oic acid top

Crystal data top

C₂₀H₂₈O₃	F(000) = 344
M_r = 316.4	D_x = 1.228 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 11 reflections
a = 8.064 (2) Å	θ = 10–11°
b = 10.775 (3) Å	µ = 0.08 mm⁻¹
c = 10.462 (4) Å	T = 296 K
β = 109.70 (2)°	Block, colourless
V = 855.8 (5) Å³	0.30 × 0.25 × 0.10 mm
Z = 2

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.000
Radiation source: fine-focus sealed tube	θ_max = 25.0°, θ_min = 2.1°
Graphite monochromator	h = −9→9
ω–2θ scans	k = 0→12
1586 measured reflections	l = 0→12
1586 independent reflections	1 standard reflections every 30 min
1254 reflections with I > 2σ(I)	intensity decay: none

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.044	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.112	w = 1/[σ²(F_o²) + (0.0704P)²] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max = 0.001
1586 reflections	Δρ_max = 0.15 e Å⁻³
218 parameters	Δρ_min = −0.17 e Å⁻³
1 restraint	Absolute structure: deduced from optical rotation
Primary atom site location: structure-invariant direct methods

Crystal data top

C₂₀H₂₈O₃	V = 855.8 (5) Å³
M_r = 316.4	Z = 2
Monoclinic, P2₁	Mo Kα radiation
a = 8.064 (2) Å	µ = 0.08 mm⁻¹
b = 10.775 (3) Å	T = 296 K
c = 10.462 (4) Å	0.30 × 0.25 × 0.10 mm
β = 109.70 (2)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.000
1586 measured reflections	1 standard reflections every 30 min
1586 independent reflections	intensity decay: none
1254 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.044	1 restraint
wR(F²) = 0.112	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 0.15 e Å⁻³
1586 reflections	Δρ_min = −0.17 e Å⁻³
218 parameters	Absolute structure: deduced from optical rotation

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.3554 (4)	0.4597 (3)	0.9863 (3)	0.0658 (8)
O2	0.4220 (4)	0.2189 (3)	0.9850 (2)	0.0620 (7)
O3	0.5758 (4)	0.1598 (3)	0.8595 (3)	0.0678 (9)
C1	0.0447 (4)	0.3543 (4)	0.6459 (4)	0.0521 (10)
C2	0.1154 (5)	0.3753 (4)	0.7994 (4)	0.0511 (9)
C3	0.2956 (5)	0.4335 (3)	0.8438 (3)	0.0473 (9)
C4	0.4293 (4)	0.3558 (3)	0.8032 (3)	0.0395 (8)
C5	0.3551 (4)	0.3369 (3)	0.6461 (3)	0.0359 (7)
C6	0.4877 (5)	0.2789 (4)	0.5853 (3)	0.0520 (9)
C7	0.4047 (5)	0.2222 (4)	0.4458 (3)	0.0572 (10)
C8	0.2344 (4)	0.2860 (4)	0.3602 (3)	0.0460 (8)
C9	0.1005 (4)	0.2857 (3)	0.4348 (3)	0.0435 (8)
C10	0.1677 (4)	0.2779 (3)	0.5907 (3)	0.0399 (8)
C11	−0.0703 (5)	0.2924 (4)	0.3625 (4)	0.0587 (10)
C12	−0.1416 (5)	0.3019 (4)	0.2107 (4)	0.0667 (12)
C13	0.0059 (6)	0.3158 (4)	0.1511 (4)	0.0609 (11)
C14	0.1503 (6)	0.2238 (4)	0.2209 (4)	0.0645 (11)
C15	0.2579 (5)	0.4187 (4)	0.3156 (3)	0.0499 (9)
C16	0.0971 (5)	0.4395 (4)	0.1910 (3)	0.0485 (9)
C17	0.0429 (5)	0.5449 (4)	0.1297 (4)	0.0567 (10)
C18	0.4701 (4)	0.2379 (3)	0.8902 (3)	0.0422 (8)
C19	0.6049 (5)	0.4288 (4)	0.8399 (4)	0.0578 (10)
C20	0.1658 (5)	0.1410 (4)	0.6329 (4)	0.0518 (9)
H1A	0.0241	0.4344	0.6009	0.062*
H1B	−0.0679	0.3121	0.6225	0.062*
H1O1	0.353 (7)	0.381 (6)	1.029 (6)	0.11 (2)*
H1O3	0.598 (6)	0.104 (5)	0.916 (5)	0.070 (14)*
H2A	0.0352	0.4289	0.8251	0.061*
H2B	0.1212	0.2965	0.8455	0.061*
H3A	0.2844	0.5133	0.7966	0.057*
H5	0.3378	0.4215	0.6096	0.043*
H6A	0.5700	0.3427	0.5799	0.062*
H6B	0.5545	0.2152	0.6467	0.062*
H7A	0.3802	0.1353	0.4561	0.069*
H7B	0.4886	0.2262	0.3977	0.069*
H11	−0.1504	0.2912	0.4089	0.070*
H12A	−0.2197	0.3730	0.1847	0.080*
H12B	−0.2097	0.2281	0.1736	0.080*
H13	−0.0373	0.3044	0.0524	0.073*
H14A	0.2340	0.2154	0.1732	0.077*
H14B	0.1024	0.1429	0.2294	0.077*
H15A	0.2618	0.4781	0.3863	0.060*
H15B	0.3652	0.4260	0.2937	0.060*
H17A	−0.0600	0.5480	0.0549	0.068*
H17B	0.1071	0.6171	0.1610	0.068*
H19A	0.6417	0.4530	0.9336	0.087*
H19B	0.5881	0.5014	0.7839	0.087*
H19C	0.6936	0.3771	0.8250	0.087*
H20A	0.0491	0.1080	0.5929	0.078*
H20B	0.2006	0.1356	0.7300	0.078*
H20C	0.2464	0.0942	0.6021	0.078*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.094 (2)	0.0543 (18)	0.0541 (17)	−0.0171 (15)	0.0310 (15)	−0.0191 (14)
O2	0.0852 (18)	0.0558 (16)	0.0539 (14)	0.0077 (16)	0.0353 (14)	0.0151 (14)
O3	0.0799 (19)	0.0664 (19)	0.0635 (19)	0.0311 (16)	0.0324 (16)	0.0300 (16)
C1	0.0394 (19)	0.061 (2)	0.054 (2)	0.0037 (18)	0.0125 (16)	0.0050 (19)
C2	0.053 (2)	0.046 (2)	0.060 (2)	0.0081 (18)	0.0275 (18)	−0.0023 (18)
C3	0.067 (2)	0.0321 (18)	0.047 (2)	−0.0034 (17)	0.0240 (17)	−0.0033 (16)
C4	0.0405 (18)	0.0345 (18)	0.0401 (18)	−0.0065 (15)	0.0094 (14)	−0.0001 (15)
C5	0.0370 (16)	0.0337 (16)	0.0352 (16)	0.0009 (14)	0.0100 (13)	0.0038 (14)
C6	0.0451 (18)	0.066 (2)	0.0468 (19)	0.0127 (19)	0.0179 (16)	0.0072 (19)
C7	0.070 (2)	0.056 (2)	0.052 (2)	0.020 (2)	0.0293 (18)	0.008 (2)
C8	0.055 (2)	0.0439 (19)	0.0368 (17)	0.0057 (18)	0.0120 (15)	0.0002 (16)
C9	0.053 (2)	0.0355 (16)	0.0396 (17)	−0.0086 (17)	0.0127 (15)	−0.0014 (15)
C10	0.0408 (18)	0.0368 (18)	0.0406 (18)	−0.0055 (16)	0.0119 (15)	−0.0012 (15)
C11	0.052 (2)	0.065 (2)	0.051 (2)	−0.020 (2)	0.0080 (18)	0.004 (2)
C12	0.063 (2)	0.070 (3)	0.048 (2)	−0.025 (2)	−0.0063 (19)	0.004 (2)
C13	0.085 (3)	0.054 (3)	0.0337 (18)	0.001 (2)	0.0073 (19)	−0.0051 (16)
C14	0.095 (3)	0.047 (2)	0.047 (2)	0.007 (2)	0.019 (2)	−0.0020 (19)
C15	0.052 (2)	0.055 (2)	0.0442 (19)	−0.0005 (18)	0.0193 (16)	0.0042 (18)
C16	0.059 (2)	0.049 (2)	0.0421 (19)	0.0009 (18)	0.0233 (16)	0.0043 (17)
C17	0.049 (2)	0.058 (2)	0.065 (2)	0.0036 (19)	0.0203 (17)	0.009 (2)
C18	0.0398 (17)	0.0418 (18)	0.0397 (17)	−0.0048 (16)	0.0061 (15)	−0.0008 (16)
C19	0.052 (2)	0.057 (2)	0.058 (2)	−0.017 (2)	0.0090 (18)	0.0025 (19)
C20	0.064 (2)	0.042 (2)	0.046 (2)	−0.0102 (18)	0.0138 (17)	−0.0012 (17)

Geometric parameters (Å, º) top

O1—C3	1.432 (4)	C8—C15	1.536 (5)
O1—H1O1	0.96 (7)	C8—C14	1.538 (5)
O2—C18	1.198 (4)	C9—C11	1.331 (5)
O3—C18	1.312 (4)	C9—C10	1.537 (4)
O3—H1O3	0.82 (5)	C10—C20	1.541 (5)
C1—C2	1.529 (5)	C11—C12	1.499 (5)
C1—C10	1.544 (5)	C11—H11	0.9300
C1—H1A	0.9700	C12—C13	1.525 (6)
C1—H1B	0.9700	C12—H12A	0.9700
C2—C3	1.505 (5)	C12—H12B	0.9700
C2—H2A	0.9700	C13—C16	1.511 (6)
C2—H2B	0.9700	C13—C14	1.516 (6)
C3—C4	1.534 (5)	C13—H13	0.9800
C3—H3A	0.9800	C14—H14A	0.9700
C4—C18	1.532 (5)	C14—H14B	0.9700
C4—C19	1.551 (5)	C15—C16	1.514 (5)
C4—C5	1.562 (4)	C15—H15A	0.9700
C5—C6	1.549 (5)	C15—H15B	0.9700
C5—C10	1.559 (4)	C16—C17	1.305 (6)
C5—H5	0.9800	C17—H17A	0.9300
C6—C7	1.514 (5)	C17—H17B	0.9300
C6—H6A	0.9700	C19—H19A	0.9600
C6—H6B	0.9700	C19—H19B	0.9600
C7—C8	1.527 (5)	C19—H19C	0.9600
C7—H7A	0.9700	C20—H20A	0.9600
C7—H7B	0.9700	C20—H20B	0.9600
C8—C9	1.531 (5)	C20—H20C	0.9600

C3—O1—H1O1	105 (4)	C9—C10—C1	109.0 (3)
C18—O3—H1O3	107 (3)	C20—C10—C1	109.5 (3)
C2—C1—C10	114.4 (3)	C9—C10—C5	108.8 (2)
C2—C1—H1A	108.7	C20—C10—C5	112.7 (3)
C10—C1—H1A	108.7	C1—C10—C5	107.9 (3)
C2—C1—H1B	108.7	C9—C11—C12	124.1 (4)
C10—C1—H1B	108.7	C9—C11—H11	118.0
H1A—C1—H1B	107.6	C12—C11—H11	118.0
C3—C2—C1	111.4 (3)	C11—C12—C13	111.5 (3)
C3—C2—H2A	109.3	C11—C12—H12A	109.3
C1—C2—H2A	109.3	C13—C12—H12A	109.3
C3—C2—H2B	109.3	C11—C12—H12B	109.3
C1—C2—H2B	109.3	C13—C12—H12B	109.3
H2A—C2—H2B	108.0	H12A—C12—H12B	108.0
O1—C3—C2	110.8 (3)	C16—C13—C14	102.7 (3)
O1—C3—C4	112.0 (3)	C16—C13—C12	110.4 (3)
C2—C3—C4	112.5 (3)	C14—C13—C12	108.5 (3)
O1—C3—H3A	107.1	C16—C13—H13	111.6
C2—C3—H3A	107.1	C14—C13—H13	111.6
C4—C3—H3A	107.1	C12—C13—H13	111.6
C18—C4—C3	108.6 (3)	C13—C14—C8	101.2 (3)
C18—C4—C19	106.2 (3)	C13—C14—H14A	111.5
C3—C4—C19	108.8 (3)	C8—C14—H14A	111.5
C18—C4—C5	116.5 (3)	C13—C14—H14B	111.5
C3—C4—C5	107.9 (3)	C8—C14—H14B	111.5
C19—C4—C5	108.7 (3)	H14A—C14—H14B	109.4
C6—C5—C10	113.6 (3)	C16—C15—C8	104.0 (3)
C6—C5—C4	114.4 (3)	C16—C15—H15A	111.0
C10—C5—C4	115.1 (2)	C8—C15—H15A	111.0
C6—C5—H5	104.0	C16—C15—H15B	111.0
C10—C5—H5	104.0	C8—C15—H15B	111.0
C4—C5—H5	104.0	H15A—C15—H15B	109.0
C7—C6—C5	114.6 (3)	C17—C16—C13	125.5 (3)
C7—C6—H6A	108.6	C17—C16—C15	126.8 (4)
C5—C6—H6A	108.6	C13—C16—C15	107.7 (3)
C7—C6—H6B	108.6	C16—C17—H17A	120.0
C5—C6—H6B	108.6	C16—C17—H17B	120.0
H6A—C6—H6B	107.6	H17A—C17—H17B	120.0
C6—C7—C8	113.7 (3)	O2—C18—O3	120.7 (3)
C6—C7—H7A	108.8	O2—C18—C4	124.7 (3)
C8—C7—H7A	108.8	O3—C18—C4	114.4 (3)
C6—C7—H7B	108.8	C4—C19—H19A	109.5
C8—C7—H7B	108.8	C4—C19—H19B	109.5
H7A—C7—H7B	107.7	H19A—C19—H19B	109.5
C7—C8—C9	110.5 (3)	C4—C19—H19C	109.5
C7—C8—C15	114.8 (3)	H19A—C19—H19C	109.5
C9—C8—C15	109.7 (3)	H19B—C19—H19C	109.5
C7—C8—C14	112.5 (3)	C10—C20—H20A	109.5
C9—C8—C14	108.7 (3)	C10—C20—H20B	109.5
C15—C8—C14	100.2 (3)	H20A—C20—H20B	109.5
C11—C9—C8	118.8 (3)	C10—C20—H20C	109.5
C11—C9—C10	122.3 (3)	H20A—C20—H20C	109.5
C8—C9—C10	118.9 (3)	H20B—C20—H20C	109.5
C9—C10—C20	108.8 (3)

C10—C1—C2—C3	54.8 (4)	C2—C1—C10—C20	72.3 (4)
C1—C2—C3—O1	176.4 (3)	C2—C1—C10—C5	−50.7 (4)
C1—C2—C3—C4	−57.4 (4)	C6—C5—C10—C9	−55.0 (4)
O1—C3—C4—C18	55.0 (3)	C4—C5—C10—C9	170.5 (3)
C2—C3—C4—C18	−70.5 (3)	C6—C5—C10—C20	65.7 (4)
O1—C3—C4—C19	−60.1 (4)	C4—C5—C10—C20	−68.7 (3)
C2—C3—C4—C19	174.4 (3)	C6—C5—C10—C1	−173.2 (3)
O1—C3—C4—C5	−177.9 (3)	C4—C5—C10—C1	52.3 (4)
C2—C3—C4—C5	56.6 (3)	C8—C9—C11—C12	−0.8 (6)
C18—C4—C5—C6	−67.3 (4)	C10—C9—C11—C12	179.1 (4)
C3—C4—C5—C6	170.3 (3)	C9—C11—C12—C13	−5.6 (6)
C19—C4—C5—C6	52.5 (4)	C11—C12—C13—C16	−67.3 (5)
C18—C4—C5—C10	66.8 (4)	C11—C12—C13—C14	44.5 (5)
C3—C4—C5—C10	−55.6 (3)	C16—C13—C14—C8	42.4 (4)
C19—C4—C5—C10	−173.4 (3)	C12—C13—C14—C8	−74.4 (4)
C10—C5—C6—C7	26.2 (5)	C7—C8—C14—C13	−171.1 (3)
C4—C5—C6—C7	161.1 (3)	C9—C8—C14—C13	66.3 (4)
C5—C6—C7—C8	30.5 (5)	C15—C8—C14—C13	−48.7 (4)
C6—C7—C8—C9	−56.6 (4)	C7—C8—C15—C16	156.9 (3)
C6—C7—C8—C15	68.0 (4)	C9—C8—C15—C16	−78.1 (3)
C6—C7—C8—C14	−178.2 (3)	C14—C8—C15—C16	36.2 (3)
C7—C8—C9—C11	−154.9 (4)	C14—C13—C16—C17	161.6 (4)
C15—C8—C9—C11	77.6 (4)	C12—C13—C16—C17	−82.9 (5)
C14—C8—C9—C11	−31.1 (5)	C14—C13—C16—C15	−19.9 (4)
C7—C8—C9—C10	25.3 (4)	C12—C13—C16—C15	95.6 (4)
C15—C8—C9—C10	−102.2 (3)	C8—C15—C16—C17	167.9 (3)
C14—C8—C9—C10	149.1 (3)	C8—C15—C16—C13	−10.5 (4)
C11—C9—C10—C20	85.3 (5)	C3—C4—C18—O2	−8.6 (4)
C8—C9—C10—C20	−94.8 (4)	C19—C4—C18—O2	108.2 (4)
C11—C9—C10—C1	−34.0 (5)	C5—C4—C18—O2	−130.6 (4)
C8—C9—C10—C1	145.8 (3)	C3—C4—C18—O3	176.3 (3)
C11—C9—C10—C5	−151.5 (4)	C19—C4—C18—O3	−66.9 (4)
C8—C9—C10—C5	28.3 (4)	C5—C4—C18—O3	54.3 (4)
C2—C1—C10—C9	−168.8 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1O3···O1ⁱ	0.82 (5)	1.83 (5)	2.637 (4)	169 (5)
O1—H1O1···O2	0.96 (7)	1.94 (6)	2.651 (4)	129 (5)

Symmetry code: (i) −x+1, y−1/2, −z+2.

Experimental details

Crystal data
Chemical formula	C₂₀H₂₈O₃
M_r	316.4
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	296
a, b, c (Å)	8.064 (2), 10.775 (3), 10.462 (4)
β (°)	109.70 (2)
V (Å³)	855.8 (5)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.30 × 0.25 × 0.10

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	1586, 1586, 1254
R_int	0.000
(sin θ/λ)_max (Å⁻¹)	0.594

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.112, 1.05
No. of reflections	1586
No. of parameters	218
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.15, −0.17
Absolute structure	Deduced from optical rotation

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1O3···O1ⁱ	0.82 (5)	1.83 (5)	2.637 (4)	169 (5)
O1—H1O1···O2	0.96 (7)	1.94 (6)	2.651 (4)	129 (5)

Symmetry code: (i) −x+1, y−1/2, −z+2.

Acknowledgements

We would like to acknowledge Dr Kim Dastlick from the Institute of Molecular Biosciences at The University of Queensland for performing optical rotations, and the Chemical Analysis Laboratories, Bulleen, Victoria, for performing high resolution-mass spectrometric analyses. This research was supported by the Centre for Phytochemistry and Pharmacology at Southern Cross University and the University of New South Wales. KB is grateful to the Australian Federal Government for an Australian Postgraduate Award and to Bioactive Exports Pty. Ltd for financial assistance.

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Volume 68| Part 2| February 2012| Pages o526-o527

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