3,5,3′-Trihy­droxy-4′-meth­oxy-7-(3-methyl­but-2-en­yloxy)flavone

Zhu, S.-H.; Liu, S.-Q.

doi:10.1107/S1600536811005393

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 67| Part 3| March 2011| Page o661

doi:10.1107/S1600536811005393

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3,5,3′-Trihydroxy-4′-methoxy-7-(3-methylbut-2-enyloxy)flavone

Sheng-Hua Zhu ^a ^* and Shao-Qian Liu ^b

^aGuangdong Food and Drug Vocational College, Guangzhou 510520, People's Republic of China, and ^bJiangxi Key Laboratory of Organic Chemistry, Jiangxi Science & Technology Normal University, Nanchang 330013, People's Republic of China
^*Correspondence e-mail: zhusanmao2@163.com

(Received 18 January 2011; accepted 14 February 2011; online 19 February 2011)

The title compound pteleifolosin C, C₂₁H₂₀O₇, was isolated from the petroleum ether-soluble fraction of an indigenous Chinese tree Melicope pteleifolia (Rutaceae). The dihedral angle between the benzene rings is 2.7 (2)°. Intramolecular O—H⋯O hydrogen bonds occur. In the crystal, molecules are linked by intermolecular O—H—O hydrogen bonds.

Related literature

For the medicinal usage of M. pteleifolia in China, see: Chinese Pharmacopoeia (1977 ) and for folk use of M. pteleifolia in South East Asia, see: Gunawardana et al. (1987 ); Shaari et al. (2006 ). For related structures and background to pteleifolosin C, see: Smith et al. (2001 ); Sultana et al. (1999 ).

Experimental

Crystal data

C₂₁H₂₀O₇
M_r = 384.37
Triclinic, $[P \overline 1]$
a = 8.4073 (18) Å
b = 9.0343 (19) Å
c = 12.489 (3) Å
α = 79.371 (2)°
β = 83.519 (3)°
γ = 78.806 (3)°
V = 911.7 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 296 K
0.60 × 0.50 × 0.45 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.939, T_max = 0.954
8186 measured reflections
4103 independent reflections
3126 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.046
wR(F²) = 0.114
S = 0.98
4103 reflections
259 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5⋯O4	0.82	2.21	2.6682 (17)	115
O5—H5⋯O6ⁱ	0.82	2.04	2.7914 (16)	153
O6—H6⋯O7	0.82	2.19	2.6440 (16)	115
O2—H2⋯O4	0.82	1.88	2.6155 (17)	148
Symmetry code: (i) -x+1, -y+2, -z+1.

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 1997 ); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811005393/jh2258sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811005393/jh2258Isup2.hkl

checkCIF report

Comment top

The title substance is a new compound named pteleifolosin C, which is from petroleum ether soluble fraction of an indigenous Chinese tree Melicope pteleifolia, Rutaceae. In the southern area of China and in the neighboring district of South East Asia, Melicope pteleifolia is a medical herb and an edible plant as well (Gunawardana et al., 1987; Shaari et al., 2006). As a staple material of Guang Dong herbal tea, it also serves as a medical herb for the treatment of injury, wounds, fester and eczema (Chinese Pharmacopoeia, 1977). Nowadays it is used as a constituent in many Chinese patent medicines. In order to find its bioactive ingredients we studied the chemical composition of its leaves and found pteleifolosin C among other flavones.

Related literature top

For the medicinal usage of M. pteleifolia in China, see: Chinese Pharmacopoeia (1977) and for folk use of M. pteleifolia in South East Asia, see: Gunawardana et al. (1987); Shaari et al. (2006). For related structures and background to pteleifolosin C, see: Smith et al. (2001); Sultana et al. (1999).

Experimental top

The dried leaves powder (5 K g) of M. pteleifolia was percolated with 80% EtOH to yield crude extract which was fractionated in a Soxhlet to give petroleum ether, ethyl acetate, acetone and methanol soluble fraction successively. The petroleum ether fraction was subjected to column chromatography over silica gel using solvents of increasing polarity. The fraction obtained with 25% ethyl acetate in petroleum ether was subsequently subjected to gel filtration (Sephadex LH-20) eluting with CHCl₃ and CH₃OH (1:1) mixtures to give yellow powder, which was purified by prep. HPLC and yielded pteleifolosin C (25 mg). It is similar to the flavones found in the same genus with the O-prenylated side chain (Sultana et al., 1999; Smith et al., 2001). ¹HNMR (500 MHz, DMSO-d₆): δ 9.55 (1H, s, –OH), 12.43 (1H, s, –OH), 6.33 (1H, d, J=2.0 Hz), 6.72 (1H, d, J=2.0 Hz), 7.72 (1H, d, J=1.6 Hz), 9.31 (1H, s, –OH), 7.09 (1H, d, J=8.5 Hz), 7.68 (1H, d, J=1.6, 8.5 Hz), 4.64 (2H, d, J=6.5 Hz), 5.46 (1H, t, J=6.5 Hz), 1.76 (3H, s), 1.73 (3H, s), 3.85 (3H, s);

The dihedral angle between the benzene ring C6—C11 and the benzene ring C15—C20 is 2.7 (2)°. and the dihedral angle between the ring C8, C9, C12, C13, C14, O3 and the benzene ring C15—C20 is 2.2 (2) °. The C2—C4 (1.319 (2) Å) and C13—C14 (1.359 (2) Å) are double bands and are significantly shorter than the other C—C bond (e.g.The distance between the single band C1—C2 is 1.495 (3) Å)

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. Molecular view the atom-labelling scheme. Ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii.

3,5-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)-7-[(3-methylbut-2-en-1- yl)oxy]chromen-4-one top

Crystal data top

C₂₁H₂₀O₇	Z = 2
M_r = 384.37	F(000) = 404
Triclinic, P1	D_x = 1.400 Mg m⁻³
a = 8.4073 (18) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.0343 (19) Å	Cell parameters from 3191 reflections
c = 12.489 (3) Å	θ = 0.0–0.0°
α = 79.371 (2)°	µ = 0.11 mm⁻¹
β = 83.519 (3)°	T = 296 K
γ = 78.806 (3)°	Block, colourless
V = 911.7 (3) Å³	0.60 × 0.50 × 0.45 mm

Data collection top

Bruker APEXII CCD diffractometer	4103 independent reflections
Radiation source: fine-focus sealed tube	3126 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
ϕ and ω scans	θ_max = 27.5°, θ_min = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→10
T_min = 0.939, T_max = 0.954	k = −11→11
8186 measured reflections	l = −16→16

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.114	H-atom parameters constrained
S = 0.98	w = 1/[σ²(F_o²) + (0.0437P)² + 0.4019P] where P = (F_o² + 2F_c²)/3
4103 reflections	(Δ/σ)_max = 0.001
259 parameters	Δρ_max = 0.21 e Å⁻³
0 restraints	Δρ_min = −0.22 e Å⁻³

Crystal data top

C₂₁H₂₀O₇	γ = 78.806 (3)°
M_r = 384.37	V = 911.7 (3) Å³
Triclinic, P1	Z = 2
a = 8.4073 (18) Å	Mo Kα radiation
b = 9.0343 (19) Å	µ = 0.11 mm⁻¹
c = 12.489 (3) Å	T = 296 K
α = 79.371 (2)°	0.60 × 0.50 × 0.45 mm
β = 83.519 (3)°

Data collection top

Bruker APEXII CCD diffractometer	4103 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	3126 reflections with I > 2σ(I)
T_min = 0.939, T_max = 0.954	R_int = 0.019
8186 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.046	0 restraints
wR(F²) = 0.114	H-atom parameters constrained
S = 0.98	Δρ_max = 0.21 e Å⁻³
4103 reflections	Δρ_min = −0.22 e Å⁻³
259 parameters

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
C5	0.0698 (2)	0.01370 (19)	0.72012 (14)	0.0408 (4)
H5A	0.1690	−0.0115	0.6744	0.049*
H5B	−0.0105	0.0810	0.6751	0.049*
C2	−0.0595 (2)	−0.21729 (19)	0.72655 (15)	0.0416 (4)
C4	0.0075 (2)	−0.12862 (19)	0.77422 (14)	0.0428 (4)
H4	0.0170	−0.1574	0.8490	0.051*
C3	−0.1194 (3)	−0.3565 (2)	0.79063 (18)	0.0584 (5)
H3A	−0.0962	−0.3684	0.8656	0.088*
H3B	−0.0656	−0.4454	0.7606	0.088*
H3C	−0.2347	−0.3445	0.7866	0.088*
C1	−0.0815 (3)	−0.1880 (2)	0.60687 (17)	0.0596 (5)
H1A	−0.0403	−0.0973	0.5729	0.089*
H1B	−0.1951	−0.1745	0.5962	0.089*
H1C	−0.0234	−0.2736	0.5747	0.089*
O1	0.10023 (15)	0.08534 (13)	0.80716 (9)	0.0457 (3)
C9	0.30637 (18)	0.47465 (17)	0.75333 (12)	0.0334 (3)
C7	0.18620 (19)	0.29532 (17)	0.67786 (13)	0.0351 (3)
H7	0.1540	0.2639	0.6181	0.042*
C8	0.25584 (17)	0.42543 (17)	0.66575 (12)	0.0308 (3)
C11	0.2147 (2)	0.2601 (2)	0.87334 (13)	0.0433 (4)
H11	0.1990	0.2042	0.9429	0.052*
C6	0.16667 (19)	0.21424 (18)	0.78258 (13)	0.0368 (4)
C10	0.2850 (2)	0.38769 (19)	0.85908 (13)	0.0404 (4)
O2	0.3353 (2)	0.43126 (16)	0.94546 (10)	0.0612 (4)
H2	0.3772	0.5074	0.9245	0.092*
C14	0.33864 (17)	0.63647 (16)	0.54058 (12)	0.0296 (3)
C12	0.37894 (18)	0.60914 (17)	0.73464 (12)	0.0337 (3)
C13	0.39232 (18)	0.68726 (17)	0.62346 (12)	0.0327 (3)
O3	0.27254 (13)	0.50474 (12)	0.56215 (8)	0.0341 (3)
O4	0.42931 (16)	0.66001 (14)	0.80866 (9)	0.0477 (3)
C19	0.2782 (2)	0.69577 (18)	0.24055 (13)	0.0383 (4)
H19	0.2381	0.6470	0.1927	0.046*
C15	0.33922 (17)	0.70364 (17)	0.42430 (12)	0.0304 (3)
C18	0.33616 (19)	0.83015 (18)	0.20187 (12)	0.0348 (3)
C16	0.39856 (19)	0.83993 (17)	0.38400 (12)	0.0343 (3)
H16	0.4396	0.8888	0.4313	0.041*
C17	0.39621 (19)	0.90123 (17)	0.27506 (13)	0.0348 (3)
C20	0.27958 (19)	0.63340 (18)	0.35041 (13)	0.0356 (3)
H20	0.2400	0.5429	0.3755	0.043*
O7	0.34083 (16)	0.90551 (14)	0.09652 (9)	0.0479 (3)
O6	0.45551 (17)	1.03420 (14)	0.23818 (10)	0.0501 (3)
H6	0.4399	1.0631	0.1734	0.075*
C21	0.2862 (3)	0.8369 (2)	0.01710 (15)	0.0635 (6)
H21A	0.3524	0.7381	0.0141	0.095*
H21B	0.2944	0.9006	−0.0532	0.095*
H21C	0.1749	0.8255	0.0367	0.095*
O5	0.46006 (16)	0.81540 (14)	0.60612 (9)	0.0478 (3)
H5	0.4836	0.8311	0.6645	0.072*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C5	0.0505 (9)	0.0343 (9)	0.0406 (9)	−0.0176 (7)	−0.0023 (7)	−0.0040 (7)
C2	0.0397 (9)	0.0351 (9)	0.0512 (10)	−0.0108 (7)	0.0002 (7)	−0.0085 (8)
C4	0.0513 (10)	0.0358 (9)	0.0427 (9)	−0.0165 (7)	−0.0038 (7)	−0.0007 (7)
C3	0.0605 (12)	0.0405 (11)	0.0785 (14)	−0.0238 (9)	0.0020 (10)	−0.0096 (10)
C1	0.0662 (13)	0.0615 (13)	0.0584 (12)	−0.0201 (10)	−0.0063 (10)	−0.0191 (10)
O1	0.0668 (8)	0.0371 (7)	0.0382 (6)	−0.0282 (6)	−0.0063 (5)	0.0019 (5)
C9	0.0385 (8)	0.0312 (8)	0.0319 (8)	−0.0106 (6)	−0.0025 (6)	−0.0043 (6)
C7	0.0423 (8)	0.0333 (8)	0.0335 (8)	−0.0147 (7)	−0.0058 (6)	−0.0048 (6)
C8	0.0346 (7)	0.0284 (8)	0.0297 (7)	−0.0097 (6)	−0.0020 (6)	−0.0015 (6)
C11	0.0612 (11)	0.0411 (10)	0.0297 (8)	−0.0210 (8)	−0.0037 (7)	0.0015 (7)
C6	0.0427 (9)	0.0304 (8)	0.0386 (9)	−0.0149 (7)	−0.0032 (7)	−0.0006 (7)
C10	0.0543 (10)	0.0397 (9)	0.0311 (8)	−0.0171 (8)	−0.0049 (7)	−0.0054 (7)
O2	0.1038 (11)	0.0607 (9)	0.0313 (6)	−0.0451 (8)	−0.0121 (7)	−0.0029 (6)
C14	0.0325 (7)	0.0243 (7)	0.0332 (8)	−0.0095 (6)	−0.0021 (6)	−0.0034 (6)
C12	0.0394 (8)	0.0322 (8)	0.0326 (8)	−0.0116 (6)	−0.0038 (6)	−0.0070 (6)
C13	0.0376 (8)	0.0279 (8)	0.0350 (8)	−0.0132 (6)	−0.0029 (6)	−0.0040 (6)
O3	0.0468 (6)	0.0302 (6)	0.0292 (5)	−0.0178 (5)	−0.0057 (4)	−0.0016 (4)
O4	0.0714 (8)	0.0457 (7)	0.0350 (6)	−0.0294 (6)	−0.0104 (6)	−0.0065 (5)
C19	0.0528 (10)	0.0331 (8)	0.0344 (8)	−0.0169 (7)	−0.0096 (7)	−0.0060 (7)
C15	0.0322 (7)	0.0280 (8)	0.0316 (7)	−0.0068 (6)	−0.0032 (6)	−0.0045 (6)
C18	0.0436 (8)	0.0326 (8)	0.0283 (8)	−0.0092 (7)	−0.0039 (6)	−0.0025 (6)
C16	0.0432 (8)	0.0319 (8)	0.0320 (8)	−0.0147 (6)	−0.0046 (6)	−0.0065 (6)
C17	0.0418 (8)	0.0279 (8)	0.0367 (8)	−0.0137 (6)	−0.0026 (6)	−0.0031 (6)
C20	0.0451 (9)	0.0290 (8)	0.0357 (8)	−0.0151 (7)	−0.0054 (7)	−0.0029 (6)
O7	0.0756 (9)	0.0419 (7)	0.0299 (6)	−0.0223 (6)	−0.0089 (6)	0.0000 (5)
O6	0.0808 (9)	0.0405 (7)	0.0363 (6)	−0.0356 (6)	−0.0079 (6)	0.0029 (5)
C21	0.1061 (17)	0.0570 (13)	0.0328 (9)	−0.0242 (12)	−0.0198 (10)	−0.0021 (9)
O5	0.0753 (8)	0.0424 (7)	0.0364 (6)	−0.0362 (6)	−0.0113 (6)	−0.0028 (5)

Geometric parameters (Å, º) top

C5—O1	1.4328 (19)	C10—O2	1.3501 (19)
C5—C4	1.498 (2)	O2—H2	0.8200
C5—H5A	0.9700	C14—C13	1.359 (2)
C5—H5B	0.9700	C14—O3	1.3793 (16)
C2—C4	1.319 (2)	C14—C15	1.467 (2)
C2—C1	1.495 (3)	C12—O4	1.2513 (17)
C2—C3	1.503 (2)	C12—C13	1.440 (2)
C4—H4	0.9300	C13—O5	1.3590 (17)
C3—H3A	0.9600	C19—C18	1.380 (2)
C3—H3B	0.9600	C19—C20	1.384 (2)
C3—H3C	0.9600	C19—H19	0.9300
C1—H1A	0.9600	C15—C20	1.396 (2)
C1—H1B	0.9600	C15—C16	1.404 (2)
C1—H1C	0.9600	C18—O7	1.3655 (19)
O1—C6	1.3581 (18)	C18—C17	1.396 (2)
C9—C8	1.390 (2)	C16—C17	1.372 (2)
C9—C10	1.419 (2)	C16—H16	0.9300
C9—C12	1.433 (2)	C17—O6	1.3713 (18)
C7—C6	1.385 (2)	C20—H20	0.9300
C7—C8	1.389 (2)	O7—C21	1.421 (2)
C7—H7	0.9300	O6—H6	0.8200
C8—O3	1.3650 (18)	C21—H21A	0.9600
C11—C10	1.369 (2)	C21—H21B	0.9600
C11—C6	1.400 (2)	C21—H21C	0.9600
C11—H11	0.9300	O5—H5	0.8200

O1—C5—C4	105.77 (13)	O2—C10—C9	119.45 (14)
O1—C5—H5A	110.6	C11—C10—C9	120.28 (14)
C4—C5—H5A	110.6	C10—O2—H2	109.5
O1—C5—H5B	110.6	C13—C14—O3	119.66 (13)
C4—C5—H5B	110.6	C13—C14—C15	128.81 (13)
H5A—C5—H5B	108.7	O3—C14—C15	111.53 (12)
C4—C2—C1	123.26 (17)	O4—C12—C9	123.70 (14)
C4—C2—C3	121.40 (17)	O4—C12—C13	119.81 (14)
C1—C2—C3	115.33 (16)	C9—C12—C13	116.49 (13)
C2—C4—C5	126.59 (16)	C14—C13—O5	121.85 (14)
C2—C4—H4	116.7	C14—C13—C12	121.80 (13)
C5—C4—H4	116.7	O5—C13—C12	116.35 (13)
C2—C3—H3A	109.5	C8—O3—C14	121.51 (11)
C2—C3—H3B	109.5	C18—C19—C20	120.15 (14)
H3A—C3—H3B	109.5	C18—C19—H19	119.9
C2—C3—H3C	109.5	C20—C19—H19	119.9
H3A—C3—H3C	109.5	C20—C15—C16	118.06 (14)
H3B—C3—H3C	109.5	C20—C15—C14	120.56 (13)
C2—C1—H1A	109.5	C16—C15—C14	121.38 (13)
C2—C1—H1B	109.5	O7—C18—C19	126.65 (13)
H1A—C1—H1B	109.5	O7—C18—C17	114.35 (14)
C2—C1—H1C	109.5	C19—C18—C17	118.99 (14)
H1A—C1—H1C	109.5	C17—C16—C15	120.24 (13)
H1B—C1—H1C	109.5	C17—C16—H16	119.9
C6—O1—C5	119.15 (12)	C15—C16—H16	119.9
C8—C9—C10	118.12 (14)	C16—C17—O6	118.83 (13)
C8—C9—C12	119.70 (14)	C16—C17—C18	121.24 (14)
C10—C9—C12	122.18 (14)	O6—C17—C18	119.93 (14)
C6—C7—C8	117.30 (14)	C19—C20—C15	121.31 (14)
C6—C7—H7	121.3	C19—C20—H20	119.3
C8—C7—H7	121.3	C15—C20—H20	119.3
O3—C8—C7	116.47 (13)	C18—O7—C21	117.28 (13)
O3—C8—C9	120.82 (13)	C17—O6—H6	109.5
C7—C8—C9	122.71 (14)	O7—C21—H21A	109.5
C10—C11—C6	119.59 (15)	O7—C21—H21B	109.5
C10—C11—H11	120.2	H21A—C21—H21B	109.5
C6—C11—H11	120.2	O7—C21—H21C	109.5
O1—C6—C7	124.01 (14)	H21A—C21—H21C	109.5
O1—C6—C11	114.00 (14)	H21B—C21—H21C	109.5
C7—C6—C11	121.99 (14)	C13—O5—H5	109.5
O2—C10—C11	120.26 (15)

C1—C2—C4—C5	0.8 (3)	C15—C14—C13—C12	178.36 (14)
C3—C2—C4—C5	−179.14 (17)	O4—C12—C13—C14	−179.72 (15)
O1—C5—C4—C2	168.75 (17)	C9—C12—C13—C14	0.2 (2)
C4—C5—O1—C6	176.45 (14)	O4—C12—C13—O5	−0.4 (2)
C6—C7—C8—O3	−179.33 (14)	C9—C12—C13—O5	179.51 (14)
C6—C7—C8—C9	0.5 (2)	C7—C8—O3—C14	179.37 (13)
C10—C9—C8—O3	179.69 (14)	C9—C8—O3—C14	−0.5 (2)
C12—C9—C8—O3	−0.8 (2)	C13—C14—O3—C8	1.6 (2)
C10—C9—C8—C7	−0.2 (2)	C15—C14—O3—C8	−178.21 (12)
C12—C9—C8—C7	179.31 (14)	C13—C14—C15—C20	179.39 (15)
C5—O1—C6—C7	9.8 (2)	O3—C14—C15—C20	−0.8 (2)
C5—O1—C6—C11	−170.35 (15)	C13—C14—C15—C16	−0.9 (2)
C8—C7—C6—O1	179.81 (14)	O3—C14—C15—C16	178.91 (13)
C8—C7—C6—C11	−0.1 (2)	C20—C19—C18—O7	−179.26 (16)
C10—C11—C6—O1	179.35 (15)	C20—C19—C18—C17	0.2 (2)
C10—C11—C6—C7	−0.8 (3)	C20—C15—C16—C17	0.4 (2)
C6—C11—C10—O2	−178.46 (17)	C14—C15—C16—C17	−179.33 (14)
C6—C11—C10—C9	1.1 (3)	C15—C16—C17—O6	−179.80 (14)
C8—C9—C10—O2	178.91 (15)	C15—C16—C17—C18	−0.3 (2)
C12—C9—C10—O2	−0.5 (3)	O7—C18—C17—C16	179.55 (15)
C8—C9—C10—C11	−0.7 (2)	C19—C18—C17—C16	0.0 (2)
C12—C9—C10—C11	179.86 (16)	O7—C18—C17—O6	−1.0 (2)
C8—C9—C12—O4	−179.14 (15)	C19—C18—C17—O6	179.51 (15)
C10—C9—C12—O4	0.3 (3)	C18—C19—C20—C15	−0.1 (3)
C8—C9—C12—C13	1.0 (2)	C16—C15—C20—C19	−0.2 (2)
C10—C9—C12—C13	−179.57 (15)	C14—C15—C20—C19	179.55 (15)
O3—C14—C13—O5	179.23 (13)	C19—C18—O7—C21	−2.5 (3)
C15—C14—C13—O5	−1.0 (3)	C17—C18—O7—C21	178.09 (16)
O3—C14—C13—C12	−1.5 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5···O4	0.82	2.21	2.6682 (17)	115
O5—H5···O6ⁱ	0.82	2.04	2.7914 (16)	153
O6—H6···O7	0.82	2.19	2.6440 (16)	115
O2—H2···O4	0.82	1.88	2.6155 (17)	148

Symmetry code: (i) −x+1, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₂₁H₂₀O₇
M_r	384.37
Crystal system, space group	Triclinic, P1
Temperature (K)	296
a, b, c (Å)	8.4073 (18), 9.0343 (19), 12.489 (3)
α, β, γ (°)	79.371 (2), 83.519 (3), 78.806 (3)
V (Å³)	911.7 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.11
Crystal size (mm)	0.60 × 0.50 × 0.45

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.939, 0.954
No. of measured, independent and observed [I > 2σ(I)] reflections	8186, 4103, 3126
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.114, 0.98
No. of reflections	4103
No. of parameters	259
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.21, −0.22

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5···O4	0.82	2.21	2.6682 (17)	115
O5—H5···O6ⁱ	0.82	2.04	2.7914 (16)	153
O6—H6···O7	0.82	2.19	2.6440 (16)	115
O2—H2···O4	0.82	1.88	2.6155 (17)	148

Symmetry code: (i) −x+1, −y+2, −z+1.

Acknowledgements

We thank Professor Bing Chen for helpful discussions and assistance with the crystallization

References

Bruker (1997). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Chinese Pharmacopoeia (1977). Beijing: People's Medical Publishing House. Google Scholar
Gunawardana, Y. A. G. P., Cordell, G. A., Ruangrungsi, N., Chomya, S. & Tantivatana, P. (1987). J. Sci. Sco. Thail. 13, 107–112. CrossRef CAS Google Scholar
Shaari, K., Safri, S., Abas, F., Lajis, N. H. & Israf, D. A. (2006). Natural Product Research 20(5), 415-419. Web of Science CrossRef Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Smith, G., Bartley, J. P., Wang, E. & Bott, R. C. (2001). Acta Cryst. C57, 1336–1337. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sultana, N., Hartley, T. G. & Waterman, P. G. (1999). Phytochemistry, 50, 1249–1253. Web of Science CrossRef CAS Google Scholar