Redetermined structure, inter­molecular inter­actions and absolute configuration of royleanone

Fun, H.-K.; Chantrapromma, S.; Salae, A.W.; Razak, I.A.; Karalai, C.

doi:10.1107/S1600536811011457

organic compounds

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ISSN: 2056-9890

Volume 67| Part 5| May 2011| Pages o1032-o1033

doi:10.1107/S1600536811011457

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Redetermined structure, intermolecular interactions and absolute configuration of royleanone

Hoong-Kun Fun,^a ^*‡ Suchada Chantrapromma,^b § Abdul Wahab Salae,^a ¶ Ibrahim Abdul Razak ^a and Chatchanok Karalai ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bCrystal Materials Research Unit, Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand
^*Correspondence e-mail: hkfun@usm.my

(Received 4 March 2011; accepted 28 March 2011; online 7 April 2011)

The structure of the title diterpenoid, C₂₀H₂₈O₃, {systematic name: (4bS,8aS)-3-hydroxy-2-isopropyl-4b,8,8-trimethyl-4b,5,6,7,8,8a,9,10-octahydrophenanthrene-1,4-dione} is confirmed [Eugster et al. (1993 ). Private communication (refcode HACGUN). CCDC, Union Road, Cambridge] and its packing is now described. Its absolute structure was established by refinement against data collected with Cu radiation: the two stereogenic centres both have S configurations. One cyclohexane ring adopts a chair conformation whereas the other cyclohexane ring is in a half-chair conformation and the benzoquinone ring is slightly twisted. An intramolecular O—H⋯O hydrogen bond generates an S(5) ring motif. In the crystal, molecules are linked into chains along [010] by O—H⋯O hydrogen bonds and weak C—H⋯O interactions. The packing also features C⋯O [3.131 (3) Å] short contacts.

Related literature

For the previous determination of the title structure, see: Eugster et al. (1993). For ring conformations, see: Cremer & Pople (1975 ). For bond-length data, see: Allen et al. (1987 ). For background to Verbenaceae plants and the bioactivity of diterpenoids, see: Bunluepuech & Tewtrakul (2009 ); Edwards et al. (1962 ); Kabouche et al. (2007 ); Suresh et al. (2011 ); Slamenová et al. (2004 ); Tezuka et al. (1998 ). For a related structure, see: Razak et al. (2010 ). For hydrogen-bond motifs, see: Bernstein et al. (1995). For the stability of the temperature controller used in the data collection, see Cosier & Glazer, (1986 ).

Experimental

Crystal data

C₂₀H₂₈O₃
M_r = 316.42
Monoclinic, P 2₁
a = 10.2247 (2) Å
b = 7.6353 (1) Å
c = 10.7292 (2) Å
β = 97.992 (1)°
V = 829.48 (2) Å³
Z = 2
Cu Kα radiation
μ = 0.66 mm⁻¹
T = 100 K
0.52 × 0.31 × 0.15 mm

Data collection

Bruker APEX DUO CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.726, T_max = 0.909
5901 measured reflections
2390 independent reflections
2375 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.036
wR(F²) = 0.098
S = 1.06
2390 reflections
217 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.20 e Å⁻³
Absolute structure: Flack (1983 ) 699 Friedel pairs
Flack parameter: 0.11 (19)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H1O2⋯O1	0.88 (4)	2.05 (3)	2.5977 (18)	119 (3)
O2—H1O2⋯O3ⁱ	0.88 (4)	2.35 (4)	3.1079 (19)	145 (3)
C1—H1A⋯O1	0.97	2.38	2.993 (2)	120
C7—H7A⋯O1ⁱⁱ	0.97	2.51	3.131 (3)	122
C17—H17B⋯O2	0.96	2.49	3.071 (2)	119
C20—H20A⋯O1	0.96	2.47	3.125 (2)	125
Symmetry codes: (i) x, y-1, z; (ii) x, y+1, z.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811011457/hb5812sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811011457/hb5812Isup2.hkl

checkCIF report

Comment top

The extracts of Verbenaceae plants have been found to possess anti-HIV-1 integrase activity (Bunluepuech & Tewtrakul, 2009) and cytotoxicity (Suresh et al., 2011). During the course of our study of chemical constituents and bioactive compounds from Premna obtusifolia (Verbenaceae), the title diterpenoid (I), which is known as royleanone (Edwards et al., 1962; Tezuka et al., 1998) was isolated from the roots of this plant. Compound (I) was reported to show significant biological properties such as antioxidant (Kabouche et al., 2007) and cytotoxic activities (Slame˘nová et al., 2004). The absolute configuration of (I) was determined by making use of the anomalous scattering of Cu Kα X-radiation with the Flack parameter being refined to 0.11 (19). We herein report the crystal structure of (I).

The molecule of (I) has three fused six membered rings (Fig. 1). The two cyclohexane rings are trans fused. One cyclohexane ring (C1–C5/C10) is in a standard chair conformation whereas the other (C5–C10) is in half chair conformation, with the C5 and C6 atoms having the deviation of 0.396 (2) and -0.323 (2) Å, respectively from the plane through C7–C10 atoms and the puckering parameters Q = 0.563 (2) Å, θ = 55.20 (19)° and ϕ = 16.1 (2)° (Cremer & Pople, 1975). The benzoquinone ring (C8–C9/C11–C14/O1/O3) is slightly twisted with the maximum deviations of -0.091 (1) and 0.055 (2) Å for atoms C9 and C13, respectively, and with the puckering parameters Q = 0.1474 (19) Å, θ = 72.9 (7)° and ϕ = 86.8 (8)° (Cremer & Pople, 1975). The O1, O2 and O3 atoms lie close to the mean plane of the C8–C9/C11–C14 ring with the r.m.s. of 0.0870 (1) Å. The bond angles around C8, C9, C12 and C13 are indicative of sp² hybridization for these atoms. The orientation of the propanyl group is described by the torsion angles C12–C13–C15–C16 = -69.8 (2) and C12–C13–C15–C17 = 54.2 (2) °. Intramolecular O2—H1O2···O1 hydrogen bond (Table 1) generate S(5) ring motif (Fig. 1) (Bernstein et al., 1995). The bond distances and angles in (I) are within normal ranges (Allen et al., 1987) and comparable with a related structure (Razak et al., 2010). The absolute configuration at atoms C1 and C5 or positions 4b and 8a of royleanone are both S, which agrees with the previous stereochemistry of royleanone (Kabouche et al., 2007; Slame˘nová et al., 2004; Tezuka et al., 1998). The S,S configurations are also consistent with those in a related structure (Razak et al., 2010).

In the crystal of (I) (Fig. 2), the molecules are linked into chains along the [0 1 0] through O2—H1O2···O3 hydrogen bond and C7—H7A···O1 weak interaction (Fig. 2 and Table 1). The crystal is stabilized by these interactions together with C···O[3.131 (3) Å] short contacts.

Related literature top

For the previous determination of the title structure, see: Eugster et al. (1993). For ring conformations, see: Cremer & Pople (1975). For bond-length data, see: Allen et al. (1987). For background to Verbenaceae plants and the bioactivity of diterpenoids, see: Bunluepuech & Tewtrakul (2009); Edwards et al. (1962); Kabouche et al. (2007); Suresh et al. (2011); Slame˘nová et al. (2004); Tezuka et al. (1998). For a related structure, see: Razak et al. (2010). For hydrogen-bond motifs, see: Bernstein et al. (1995). For the stability of the temperature controller used in the data collection, see Cosier & Glazer, (1986).

Experimental top

The air-dried roots of premna obtusifolia (4.5 kg) were extracted with hexane (2 × 20 l) at room temperature. The combined extracts were concentrated under reduced pressure to give a dark yellow extract (40.0 g) which was subjected to quick column chromatography (QCC) over silica gel using solvents of increasing polarity from n-hexane to EtOAc to afford 7 fractions (F1-F7). Fraction F2 was further purified by quick column chromatography using hexane, yielding the title compound (6.1 mg). Yellow blocks were recrystallized from CH₂Cl₂ by the slow evaporation of the solvent at room temperature after several days, M.p 451-453 K.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The structure of (I), showing 40% probability displacement ellipsoids. The hydrogen bond is shown as a dashed line.
	Fig. 2. The crystal packing of (I) viewed along the a axis, showing [010] chains. Hydrogen bonds are shown as dashed lines.

(4bS,8aS)-3-hydroxy-2-isopropyl-4b,8,8-trimethyl- 4b,5,6,7,8,8a,9,10-octahydrophenanthrene-1,4-dione top

Crystal data top

C₂₀H₂₈O₃	F(000) = 344
M_r = 316.42	D_x = 1.267 Mg m⁻³
Monoclinic, P2₁	Melting point = 451–453 K
Hall symbol: P 2yb	Cu Kα radiation, λ = 1.54178 Å
a = 10.2247 (2) Å	Cell parameters from 2390 reflections
b = 7.6353 (1) Å	θ = 5.6–72.1°
c = 10.7292 (2) Å	µ = 0.66 mm⁻¹
β = 97.992 (1)°	T = 100 K
V = 829.48 (2) Å³	Block, yellow
Z = 2	0.52 × 0.31 × 0.15 mm

Data collection top

Bruker APEX Duo CCD diffractometer	2390 independent reflections
Radiation source: sealed tube	2375 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
ϕ and ω scans	θ_max = 72.1°, θ_min = 5.6°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −12→12
T_min = 0.726, T_max = 0.909	k = −9→6
5901 measured reflections	l = −13→12

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)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.098	w = 1/[σ²(F_o²) + (0.0639P)² + 0.2006P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max = 0.001
2390 reflections	Δρ_max = 0.35 e Å⁻³
217 parameters	Δρ_min = −0.20 e Å⁻³
1 restraint	Absolute structure: Flack (1983) 699 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.11 (19)

Crystal data top

C₂₀H₂₈O₃	V = 829.48 (2) Å³
M_r = 316.42	Z = 2
Monoclinic, P2₁	Cu Kα radiation
a = 10.2247 (2) Å	µ = 0.66 mm⁻¹
b = 7.6353 (1) Å	T = 100 K
c = 10.7292 (2) Å	0.52 × 0.31 × 0.15 mm
β = 97.992 (1)°

Data collection top

Bruker APEX Duo CCD diffractometer	2390 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	2375 reflections with I > 2σ(I)
T_min = 0.726, T_max = 0.909	R_int = 0.021
5901 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.098	Δρ_max = 0.35 e Å⁻³
S = 1.06	Δρ_min = −0.20 e Å⁻³
2390 reflections	Absolute structure: Flack (1983) 699 Friedel pairs
217 parameters	Absolute structure parameter: 0.11 (19)
1 restraint

Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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 (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.64538 (13)	−0.0889 (2)	0.48735 (12)	0.0254 (3)
O2	0.54777 (12)	−0.05136 (18)	0.25211 (12)	0.0219 (3)
H1O2	0.567 (3)	−0.139 (5)	0.304 (3)	0.055 (9)*
O3	0.59784 (11)	0.55637 (18)	0.31995 (11)	0.0202 (3)
C1	0.91254 (18)	0.0149 (3)	0.61639 (17)	0.0244 (4)
H1A	0.8633	−0.0932	0.6003	0.029*
H1B	0.9513	0.0438	0.5414	0.029*
C2	1.02342 (19)	−0.0129 (3)	0.72689 (19)	0.0293 (4)
H2A	0.9853	−0.0529	0.7997	0.035*
H2B	1.0828	−0.1033	0.7048	0.035*
C3	1.10107 (17)	0.1532 (3)	0.76032 (17)	0.0258 (5)
H3A	1.1496	0.1824	0.6916	0.031*
H3B	1.1652	0.1310	0.8341	0.031*
C4	1.01699 (15)	0.3115 (3)	0.78684 (15)	0.0194 (4)
C5	0.90137 (15)	0.3285 (3)	0.67650 (14)	0.0181 (4)
H5A	0.9442	0.3520	0.6020	0.022*
C6	0.80962 (18)	0.4855 (3)	0.68588 (18)	0.0264 (4)
H6A	0.7458	0.4577	0.7419	0.032*
H6B	0.8607	0.5859	0.7199	0.032*
C7	0.73866 (16)	0.5283 (3)	0.55608 (16)	0.0194 (4)
H7A	0.6623	0.6004	0.5646	0.023*
H7B	0.7972	0.5959	0.5108	0.023*
C8	0.69435 (15)	0.3689 (2)	0.48092 (15)	0.0155 (4)
C9	0.72317 (14)	0.2047 (2)	0.52206 (14)	0.0153 (4)
C10	0.81709 (15)	0.1624 (2)	0.64288 (14)	0.0153 (3)
C11	0.65384 (15)	0.0604 (3)	0.44783 (15)	0.0174 (4)
C12	0.58810 (16)	0.0954 (3)	0.31623 (15)	0.0175 (4)
C13	0.57151 (15)	0.2572 (3)	0.26820 (15)	0.0165 (4)
C14	0.61740 (15)	0.4041 (3)	0.35330 (15)	0.0156 (3)
C15	0.51364 (15)	0.3012 (3)	0.13372 (14)	0.0184 (4)
H15A	0.5037	0.4287	0.1280	0.022*
C16	0.61027 (18)	0.2461 (3)	0.04345 (16)	0.0260 (4)
H16A	0.6936	0.3034	0.0671	0.039*
H16B	0.5750	0.2790	−0.0409	0.039*
H16C	0.6226	0.1215	0.0477	0.039*
C17	0.37759 (17)	0.2199 (3)	0.09225 (18)	0.0262 (4)
H17A	0.3187	0.2518	0.1508	0.039*
H17B	0.3856	0.0947	0.0900	0.039*
H17C	0.3431	0.2621	0.0099	0.039*
C18	1.10451 (18)	0.4757 (3)	0.78830 (19)	0.0294 (5)
H18A	1.1833	0.4592	0.8472	0.044*
H18B	1.0570	0.5755	0.8129	0.044*
H18C	1.1279	0.4948	0.7058	0.044*
C19	0.97379 (18)	0.2988 (3)	0.91827 (15)	0.0266 (4)
H19A	1.0493	0.3138	0.9813	0.040*
H19B	0.9350	0.1860	0.9281	0.040*
H19C	0.9101	0.3886	0.9274	0.040*
C20	0.73179 (17)	0.1029 (3)	0.74287 (16)	0.0265 (4)
H20A	0.6730	0.0115	0.7087	0.040*
H20B	0.6813	0.2003	0.7666	0.040*
H20C	0.7880	0.0598	0.8155	0.040*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0347 (7)	0.0149 (7)	0.0236 (6)	−0.0044 (6)	−0.0064 (5)	0.0030 (5)
O2	0.0283 (6)	0.0142 (8)	0.0208 (6)	−0.0021 (5)	−0.0050 (5)	−0.0011 (5)
O3	0.0217 (6)	0.0152 (7)	0.0221 (6)	−0.0003 (5)	−0.0024 (4)	0.0026 (5)
C1	0.0284 (8)	0.0194 (11)	0.0228 (8)	0.0053 (8)	−0.0062 (7)	−0.0049 (7)
C2	0.0307 (9)	0.0224 (11)	0.0313 (10)	0.0092 (9)	−0.0082 (7)	−0.0048 (9)
C3	0.0194 (8)	0.0331 (13)	0.0227 (8)	0.0065 (8)	−0.0046 (6)	−0.0044 (8)
C4	0.0183 (7)	0.0220 (11)	0.0169 (7)	−0.0007 (8)	−0.0006 (6)	−0.0001 (7)
C5	0.0189 (7)	0.0198 (10)	0.0152 (7)	−0.0025 (7)	0.0009 (6)	0.0001 (7)
C6	0.0310 (9)	0.0199 (10)	0.0258 (9)	0.0003 (8)	−0.0055 (7)	−0.0054 (8)
C7	0.0224 (7)	0.0148 (10)	0.0207 (8)	−0.0005 (7)	0.0016 (6)	−0.0011 (7)
C8	0.0143 (7)	0.0157 (10)	0.0163 (7)	−0.0009 (6)	0.0020 (6)	−0.0002 (6)
C9	0.0147 (6)	0.0167 (10)	0.0145 (7)	−0.0008 (6)	0.0020 (5)	−0.0005 (6)
C10	0.0172 (7)	0.0158 (9)	0.0124 (7)	−0.0013 (7)	0.0005 (6)	0.0006 (6)
C11	0.0177 (7)	0.0158 (10)	0.0182 (7)	0.0007 (7)	0.0015 (6)	0.0008 (7)
C12	0.0176 (7)	0.0167 (11)	0.0178 (8)	−0.0011 (7)	0.0016 (6)	−0.0020 (7)
C13	0.0141 (7)	0.0179 (10)	0.0170 (8)	0.0000 (6)	0.0004 (6)	−0.0003 (7)
C14	0.0132 (6)	0.0157 (9)	0.0181 (7)	0.0007 (6)	0.0029 (6)	−0.0001 (7)
C15	0.0220 (7)	0.0160 (10)	0.0161 (7)	0.0003 (7)	−0.0016 (6)	0.0009 (7)
C16	0.0301 (9)	0.0294 (12)	0.0181 (8)	0.0049 (8)	0.0020 (6)	0.0026 (7)
C17	0.0224 (8)	0.0256 (11)	0.0277 (8)	0.0000 (8)	−0.0065 (6)	−0.0001 (8)
C18	0.0268 (9)	0.0307 (12)	0.0281 (9)	−0.0091 (9)	−0.0056 (7)	0.0027 (9)
C19	0.0277 (8)	0.0341 (12)	0.0167 (8)	−0.0016 (8)	−0.0013 (6)	−0.0050 (8)
C20	0.0225 (8)	0.0388 (13)	0.0181 (8)	−0.0087 (8)	0.0020 (6)	0.0034 (8)

Geometric parameters (Å, º) top

O1—C11	1.224 (2)	C8—C14	1.506 (2)
O2—C12	1.349 (2)	C9—C11	1.481 (2)
O2—H1O2	0.88 (4)	C9—C10	1.536 (2)
O3—C14	1.225 (2)	C10—C20	1.542 (2)
C1—C2	1.537 (2)	C11—C12	1.501 (2)
C1—C10	1.542 (2)	C12—C13	1.341 (3)
C1—H1A	0.9700	C13—C14	1.481 (3)
C1—H1B	0.9700	C13—C15	1.519 (2)
C2—C3	1.513 (3)	C15—C17	1.532 (2)
C2—H2A	0.9700	C15—C16	1.535 (2)
C2—H2B	0.9700	C15—H15A	0.9800
C3—C4	1.533 (3)	C16—H16A	0.9600
C3—H3A	0.9700	C16—H16B	0.9600
C3—H3B	0.9700	C16—H16C	0.9600
C4—C19	1.538 (2)	C17—H17A	0.9600
C4—C18	1.539 (3)	C17—H17B	0.9600
C4—C5	1.558 (2)	C17—H17C	0.9600
C5—C6	1.534 (3)	C18—H18A	0.9600
C5—C10	1.548 (3)	C18—H18B	0.9600
C5—H5A	0.9800	C18—H18C	0.9600
C6—C7	1.514 (2)	C19—H19A	0.9600
C6—H6A	0.9700	C19—H19B	0.9600
C6—H6B	0.9700	C19—H19C	0.9600
C7—C8	1.495 (2)	C20—H20A	0.9600
C7—H7A	0.9700	C20—H20B	0.9600
C7—H7B	0.9700	C20—H20C	0.9600
C8—C9	1.348 (3)

C12—O2—H1O2	107 (2)	C9—C10—C5	106.69 (14)
C2—C1—C10	112.12 (15)	C20—C10—C5	115.45 (14)
C2—C1—H1A	109.2	C1—C10—C5	107.17 (13)
C10—C1—H1A	109.2	O1—C11—C9	123.94 (15)
C2—C1—H1B	109.2	O1—C11—C12	116.59 (16)
C10—C1—H1B	109.2	C9—C11—C12	119.46 (16)
H1A—C1—H1B	107.9	C13—C12—O2	123.80 (15)
C3—C2—C1	111.93 (18)	C13—C12—C11	122.80 (16)
C3—C2—H2A	109.2	O2—C12—C11	113.40 (16)
C1—C2—H2A	109.2	C12—C13—C14	116.67 (14)
C3—C2—H2B	109.2	C12—C13—C15	125.48 (17)
C1—C2—H2B	109.2	C14—C13—C15	117.82 (16)
H2A—C2—H2B	107.9	O3—C14—C13	120.92 (15)
C2—C3—C4	114.57 (15)	O3—C14—C8	118.62 (15)
C2—C3—H3A	108.6	C13—C14—C8	120.41 (16)
C4—C3—H3A	108.6	C13—C15—C17	113.86 (15)
C2—C3—H3B	108.6	C13—C15—C16	109.82 (14)
C4—C3—H3B	108.6	C17—C15—C16	110.11 (15)
H3A—C3—H3B	107.6	C13—C15—H15A	107.6
C3—C4—C19	111.12 (16)	C17—C15—H15A	107.6
C3—C4—C18	107.69 (15)	C16—C15—H15A	107.6
C19—C4—C18	106.43 (16)	C15—C16—H16A	109.5
C3—C4—C5	108.09 (14)	C15—C16—H16B	109.5
C19—C4—C5	114.68 (13)	H16A—C16—H16B	109.5
C18—C4—C5	108.58 (15)	C15—C16—H16C	109.5
C6—C5—C10	109.26 (13)	H16A—C16—H16C	109.5
C6—C5—C4	114.94 (15)	H16B—C16—H16C	109.5
C10—C5—C4	116.62 (16)	C15—C17—H17A	109.5
C6—C5—H5A	104.9	C15—C17—H17B	109.5
C10—C5—H5A	104.9	H17A—C17—H17B	109.5
C4—C5—H5A	104.9	C15—C17—H17C	109.5
C7—C6—C5	109.12 (15)	H17A—C17—H17C	109.5
C7—C6—H6A	109.9	H17B—C17—H17C	109.5
C5—C6—H6A	109.9	C4—C18—H18A	109.5
C7—C6—H6B	109.9	C4—C18—H18B	109.5
C5—C6—H6B	109.9	H18A—C18—H18B	109.5
H6A—C6—H6B	108.3	C4—C18—H18C	109.5
C8—C7—C6	113.02 (17)	H18A—C18—H18C	109.5
C8—C7—H7A	109.0	H18B—C18—H18C	109.5
C6—C7—H7A	109.0	C4—C19—H19A	109.5
C8—C7—H7B	109.0	C4—C19—H19B	109.5
C6—C7—H7B	109.0	H19A—C19—H19B	109.5
H7A—C7—H7B	107.8	C4—C19—H19C	109.5
C9—C8—C7	122.99 (14)	H19A—C19—H19C	109.5
C9—C8—C14	121.79 (15)	H19B—C19—H19C	109.5
C7—C8—C14	115.20 (15)	C10—C20—H20A	109.5
C8—C9—C11	116.69 (14)	C10—C20—H20B	109.5
C8—C9—C10	123.65 (15)	H20A—C20—H20B	109.5
C11—C9—C10	119.60 (16)	C10—C20—H20C	109.5
C9—C10—C20	107.53 (12)	H20A—C20—H20C	109.5
C9—C10—C1	109.58 (13)	H20B—C20—H20C	109.5
C20—C10—C1	110.27 (16)

C10—C1—C2—C3	−56.7 (2)	C4—C5—C10—C9	−172.64 (13)
C1—C2—C3—C4	54.2 (2)	C6—C5—C10—C20	−64.48 (19)
C2—C3—C4—C19	76.8 (2)	C4—C5—C10—C20	67.96 (19)
C2—C3—C4—C18	−167.00 (15)	C6—C5—C10—C1	172.24 (13)
C2—C3—C4—C5	−49.9 (2)	C4—C5—C10—C1	−55.33 (17)
C3—C4—C5—C6	−177.96 (16)	C8—C9—C11—O1	−162.38 (16)
C19—C4—C5—C6	57.5 (2)	C10—C9—C11—O1	14.7 (2)
C18—C4—C5—C6	−61.40 (19)	C8—C9—C11—C12	17.2 (2)
C3—C4—C5—C10	52.25 (18)	C10—C9—C11—C12	−165.74 (13)
C19—C4—C5—C10	−72.3 (2)	O1—C11—C12—C13	169.20 (16)
C18—C4—C5—C10	168.81 (14)	C9—C11—C12—C13	−10.4 (2)
C10—C5—C6—C7	−68.58 (19)	O1—C11—C12—O2	−10.7 (2)
C4—C5—C6—C7	158.12 (15)	C9—C11—C12—O2	169.71 (14)
C5—C6—C7—C8	40.90 (19)	O2—C12—C13—C14	177.82 (14)
C6—C7—C8—C9	−4.3 (2)	C11—C12—C13—C14	−2.1 (2)
C6—C7—C8—C14	177.17 (14)	O2—C12—C13—C15	−4.1 (2)
C7—C8—C9—C11	169.78 (13)	C11—C12—C13—C15	176.03 (14)
C14—C8—C9—C11	−11.8 (2)	C12—C13—C14—O3	−174.92 (15)
C7—C8—C9—C10	−7.2 (2)	C15—C13—C14—O3	6.8 (2)
C14—C8—C9—C10	171.21 (13)	C12—C13—C14—C8	7.7 (2)
C8—C9—C10—C20	105.79 (19)	C15—C13—C14—C8	−170.58 (13)
C11—C9—C10—C20	−71.10 (19)	C9—C8—C14—O3	−177.84 (15)
C8—C9—C10—C1	−134.34 (17)	C7—C8—C14—O3	0.68 (19)
C11—C9—C10—C1	48.77 (19)	C9—C8—C14—C13	−0.4 (2)
C8—C9—C10—C5	−18.63 (19)	C7—C8—C14—C13	178.12 (13)
C11—C9—C10—C5	164.48 (13)	C12—C13—C15—C17	54.2 (2)
C2—C1—C10—C9	170.62 (16)	C14—C13—C15—C17	−127.68 (17)
C2—C1—C10—C20	−71.2 (2)	C12—C13—C15—C16	−69.8 (2)
C2—C1—C10—C5	55.2 (2)	C14—C13—C15—C16	108.33 (18)
C6—C5—C10—C9	54.93 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1O2···O1	0.88 (4)	2.05 (3)	2.5977 (18)	119 (3)
O2—H1O2···O3ⁱ	0.88 (4)	2.35 (4)	3.1079 (19)	145 (3)
C1—H1A···O1	0.97	2.38	2.993 (2)	120
C7—H7A···O1ⁱⁱ	0.97	2.51	3.131 (3)	122
C17—H17B···O2	0.96	2.49	3.071 (2)	119
C20—H20A···O1	0.96	2.47	3.125 (2)	125

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

Experimental details

Crystal data
Chemical formula	C₂₀H₂₈O₃
M_r	316.42
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	100
a, b, c (Å)	10.2247 (2), 7.6353 (1), 10.7292 (2)
β (°)	97.992 (1)
V (Å³)	829.48 (2)
Z	2
Radiation type	Cu Kα
µ (mm⁻¹)	0.66
Crystal size (mm)	0.52 × 0.31 × 0.15

Data collection
Diffractometer	Bruker APEX Duo CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.726, 0.909
No. of measured, independent and observed [I > 2σ(I)] reflections	5901, 2390, 2375
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.098, 1.06
No. of reflections	2390
No. of parameters	217
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)	0.35, −0.20
Absolute structure	Flack (1983) 699 Friedel pairs
Absolute structure parameter	0.11 (19)

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1O2···O1	0.88 (4)	2.05 (3)	2.5977 (18)	119 (3)
O2—H1O2···O3ⁱ	0.88 (4)	2.35 (4)	3.1079 (19)	145 (3)
C1—H1A···O1	0.97	2.38	2.993 (2)	120
C7—H7A···O1ⁱⁱ	0.97	2.51	3.131 (3)	122
C17—H17B···O2	0.96	2.49	3.071 (2)	119
C20—H20A···O1	0.96	2.47	3.125 (2)	125

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

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

§Additional correspondence author, e-mail: suchada.c@psu.ac.th. Thomson Reuters ResearcherID: A-5085-2009.

¶On PhD study leave from Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand.

Acknowledgements

AWS thanks Universiti Sains Malaysia for the PhD student visiting fellowship. SC thanks the Prince of Songkla University for generous support. The authors thank Universiti Sains Malaysia for the Research University Grant No.1001/PFIZIK/811151.

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