4-Formyl­phenyl 2,3,4,6-tetra-O-acetyl-β-d-allopyran­oside

Ye, D.; Zhang, K.; Chen, H.; Yin, S.; Li, Y.

doi:10.1107/S1600536809018248

organic compounds

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ISSN: 2056-9890

Volume 65| Part 6| June 2009| Page o1338

doi:10.1107/S1600536809018248

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4-Formylphenyl 2,3,4,6-tetra-O-acetyl-β-D-allopyranoside

Ding Ye,^a Kuan Zhang,^a Hua-feng Chen,^a Shu-fan Yin ^a and Ying Li ^a ^*

^aCollege of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China
^*Correspondence e-mail: chuandayouji217@163.com

(Received 19 March 2009; accepted 14 May 2009; online 20 May 2009)

The title compound, C₂₁H₂₄O₁₁, crystallizes exclusively as the β-anomer. The substituent of the protected sugar at position C-3 is in the axial position, while all other groups are in equatorial positions. The pyranoside ring adopts a stable chair conformation.

Related literature

For the synthesis see: Chen et al. (1981 ); Wen et al. (2008 ). For the pharmacological activities of helicid derivatives, see: Fan et al. (2008 ), Sha et al. (1987 ). For related structures, see: Burkhardt et al. (2007a , 2007b )

Experimental

Crystal data

C₂₁H₂₄O₁₁
M_r = 452.40
Monoclinic, P 2₁
a = 7.056 (4) Å
b = 17.758 (6) Å
c = 9.129 (3) Å
β = 102.80 (4)°
V = 1115.4 (8) Å³
Z = 2
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 291 K
0.44 × 0.42 × 0.20 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: none
4596 measured reflections
4149 independent reflections
2143 reflections with I > 2σ(I)
R_int = 0.029
3 standard reflections every 150 reflections intensity decay: 3.7%

Refinement

R[F² > 2σ(F²)] = 0.050
wR(F²) = 0.143
S = 0.95
4149 reflections
293 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: DIFRAC (Gabe & White, 1993 ); cell refinement: DIFRAC; data reduction: NRCVAX (Gabe et al., 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 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809018248/bx2200sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809018248/bx2200Isup2.hkl

checkCIF report

Comment top

The natural compound helicid, 4-(β-D-allopyranosyloxy)benzaldehyde (Chen et al., 1981), is a major active ingredient of Chinese herbal medicine, which has good biological effects on central nervous system with low toxicity (Sha et al., 1987). Some helicid derivatives have been reported with good pharmacological activities (Fan et al., 2008). The title compound, a new helicid derivative, was synthesized via reaction of helicid and acetyl anhydride with good yield of 98% (Wen et al., 2008). Herein, we describe the structure of 4-formylphenyl-2,3, 4,6-tetra-O-acetyl-β-D-allopyranoside which compare well with the related structures 3-Formylphenyl-2,3,4,6-tetra-O-acetyl-β-D– glucopyranoside (Burkhardt et al., 2007a) and 3-Formylphenyl-2,3,4,6-tetra-O-acetyl-α -D– glucopyranoside (Burkhardt et al., 2007b) . The 4-formylphenyl group is subsituted at anomeric atom C1. The remaining hydroxy groups at C2, C3, C4 and C6 are protected by acetyl groups. Due to its hydrophobic substituents the compound is soluble in less polar solvents such as CH₂Cl₂. The 4-formylphenyl substituent at C1 is in an equatorial position, corresponding to the exclusive presence of the β anomer of the saccharide.The substituent of the protected sugar at C3 is in the axial position.

Related literature top

For the synthesis see: Chen et al. (1981); Wen et al. (2008). For the pharmacological activities of helicid derivatives, see: Fan et al. (2008), Sha et al. (1987). For related structures, see: Burkhardt et al. (2007a, 2007b)

Experimental top

To a solution of helicid (1.0 g, 3.5 mmol) in 2 ml of DMF and 3 ml of TEA was added dropwise acetyl anhydride (2.5 g, 25 mmol) under ice bath. The mixture was stirred vigorously at room temperature 5 h, and then poured into 20 ml of ice water. The precipitate was filtered, washed with water, and recrystallized with ethanol. By slow evaporation at room temperature, we got colorless crystals, yield 98%, m.p.:408–409 K. IR (KBr): 1752, 1693, 1601, 1506, 1224, 1157, 1127, 1085, 914, 876; ¹H NMR (400 MHz, CDCl₃, 298 K): 2.18, 2.08, 2.05, 2.05 (4 s, 12H, CH3); 4.26–4.24 (m, 2H, H6a, H6e); 4.32–4.27 (m, 1H, H5); 5.16 (dd, 1H, J₄₃ = 2.8 Hz, J₄₅ = 9.9 Hz, H4); 5.19 (dd, 1H, J₂₃ = 3.0 Hz, J₂₁ = 8.1 Hz, H2); 5.48 (d, 1H, J₁₂ = 8.1 Hz, H1); 5.75 (t, 1H, J₃₂ = 2.9 Hz, H3); 7.85 (d, 2H, J₈₉ = J₁₂₁₁ = 8.6 Hz, ArH); 7.13 (d, 2H, J₉₁₀ = J₁₁₁₀ = 8.6 Hz, ArH); 9.91 (s, 1H, H—C=O) p.p.m. ¹³C NMR (100 MHz, CDCl₃, 298 K): 191.2, 170.8, 170.6, 170.5, 169.8, 161.7, 132.3, 117.2, 99.0, 71.8, 71.1, 68.8, 67.2, 61.8, 21.2, 21.1,21.0 p.p.m. ESI-MS: m/z (%) = 475 [M + Na]⁺ (100). Analysis calculated for C₂₁H₂₄O₁₁.

Computing details top

Data collection: DIFRAC (Gabe & White, 1993); cell refinement: DIFRAC (Gabe et al., 1989); data reduction: NRCVAX (Gabe et al., 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); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of (I), with displacement ellipsoids drawn at the 30% probability level.

4-Formylphenyl 2,3,4,6-tetra-O-acetyl-β-D-allopyranoside top

Crystal data top

C₂₁H₂₄O₁₁	F(000) = 476
M_r = 452.40	D_x = 1.347 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 33 reflections
a = 7.056 (4) Å	θ = 4.6–9.4°
b = 17.758 (6) Å	µ = 0.11 mm⁻¹
c = 9.129 (3) Å	T = 291 K
β = 102.80 (4)°	Block, colourless
V = 1115.4 (8) Å³	0.44 × 0.42 × 0.20 mm
Z = 2

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.029
Radiation source: fine-focus sealed tube	θ_max = 32.5°, θ_min = 2.3°
Graphite monochromator	h = −10→10
ω/2θ scans	k = −25→26
4596 measured reflections	l = −13→13
4149 independent reflections	3 standard reflections every 150 reflections
2143 reflections with I > 2σ(I)	intensity decay: 3.7%

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.143	H-atom parameters constrained
S = 0.95	w = 1/[σ²(F_o²) + (0.0778P)²] where P = (F_o² + 2F_c²)/3
4149 reflections	(Δ/σ)_max < 0.001
293 parameters	Δρ_max = 0.30 e Å⁻³
1 restraint	Δρ_min = −0.20 e Å⁻³

Crystal data top

C₂₁H₂₄O₁₁	V = 1115.4 (8) Å³
M_r = 452.40	Z = 2
Monoclinic, P2₁	Mo Kα radiation
a = 7.056 (4) Å	µ = 0.11 mm⁻¹
b = 17.758 (6) Å	T = 291 K
c = 9.129 (3) Å	0.44 × 0.42 × 0.20 mm
β = 102.80 (4)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.029
4596 measured reflections	3 standard reflections every 150 reflections
4149 independent reflections	intensity decay: 3.7%
2143 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.050	1 restraint
wR(F²) = 0.143	H-atom parameters constrained
S = 0.95	Δρ_max = 0.30 e Å⁻³
4149 reflections	Δρ_min = −0.20 e Å⁻³
293 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
O1	0.4950 (3)	0.63276 (10)	0.1617 (2)	0.0399 (4)
O2	0.2064 (3)	0.55171 (14)	−0.0604 (2)	0.0526 (5)
O3	0.3692 (5)	0.62506 (18)	−0.1903 (3)	0.0857 (9)
O4	0.2271 (3)	0.48018 (11)	0.2871 (2)	0.0436 (4)
O5	−0.0540 (3)	0.52455 (15)	0.3289 (4)	0.0733 (8)
O6	0.5256 (3)	0.54679 (12)	0.5011 (2)	0.0446 (4)
O7	0.3283 (4)	0.48347 (14)	0.6212 (3)	0.0657 (7)
O8	0.5465 (3)	0.69998 (12)	0.5428 (2)	0.0468 (5)
O9	0.2909 (5)	0.7687 (2)	0.5597 (4)	0.1025 (12)
O10	0.6171 (3)	0.74339 (10)	0.2628 (2)	0.0415 (4)
O11	1.2834 (4)	0.88786 (18)	−0.0222 (3)	0.0780 (8)
C1	0.5854 (4)	0.66770 (14)	0.2979 (3)	0.0370 (5)
H1	0.7070	0.6424	0.3454	0.044*
C2	0.4428 (4)	0.67009 (15)	0.4018 (3)	0.0385 (6)
H2	0.3343	0.7036	0.3589	0.046*
C3	0.3648 (4)	0.59176 (16)	0.4229 (3)	0.0394 (6)
H3	0.2627	0.5944	0.4801	0.047*
C4	0.2873 (4)	0.55657 (15)	0.2697 (3)	0.0388 (6)
H4	0.1757	0.5858	0.2156	0.047*
C5	0.4441 (4)	0.55511 (15)	0.1781 (3)	0.0382 (6)
H5	0.5581	0.5283	0.2352	0.046*
C6	0.3858 (4)	0.52131 (17)	0.0245 (3)	0.0482 (7)
H6A	0.4876	0.5304	−0.0293	0.058*
H6B	0.3723	0.4673	0.0338	0.058*
C7	0.2171 (6)	0.6017 (2)	−0.1706 (4)	0.0620 (9)
C8	0.0234 (7)	0.6216 (3)	−0.2607 (5)	0.0897 (13)
H8A	0.0274	0.6713	−0.3014	0.135*
H8B	−0.0694	0.6204	−0.1981	0.135*
H8C	−0.0141	0.5862	−0.3412	0.135*
C9	0.0503 (4)	0.47285 (19)	0.3242 (4)	0.0528 (8)
C10	0.0162 (6)	0.3927 (2)	0.3635 (5)	0.0743 (11)
H10A	0.0886	0.3821	0.4634	0.111*
H10B	0.0578	0.3596	0.2937	0.111*
H10C	−0.1198	0.3851	0.3586	0.111*
C11	0.4840 (5)	0.49291 (18)	0.5944 (3)	0.0535 (8)
C12	0.6629 (7)	0.4484 (3)	0.6583 (6)	0.0856 (13)
H12A	0.7167	0.4648	0.7591	0.128*
H12B	0.7566	0.4557	0.5978	0.128*
H12C	0.6303	0.3959	0.6590	0.128*
C13	0.4540 (5)	0.75101 (18)	0.6110 (4)	0.0563 (8)
C14	0.5769 (7)	0.7780 (3)	0.7549 (5)	0.0842 (13)
H14A	0.5345	0.8273	0.7771	0.126*
H14B	0.7100	0.7804	0.7465	0.126*
H14C	0.5656	0.7439	0.8341	0.126*
C15	0.7685 (4)	0.75945 (14)	0.1960 (3)	0.0359 (5)
C16	0.8011 (4)	0.83541 (16)	0.1761 (3)	0.0430 (6)
H16	0.7223	0.8714	0.2069	0.052*
C17	0.9503 (4)	0.85760 (16)	0.1108 (3)	0.0453 (7)
H17	0.9704	0.9085	0.0961	0.054*
C18	1.0703 (4)	0.80472 (17)	0.0669 (3)	0.0417 (6)
C19	1.0361 (4)	0.72875 (17)	0.0863 (3)	0.0460 (7)
H19	1.1167	0.6930	0.0568	0.055*
C20	0.8838 (4)	0.70516 (16)	0.1487 (3)	0.0443 (6)
H20	0.8594	0.6542	0.1587	0.053*
C21	1.2373 (5)	0.8255 (2)	0.0018 (4)	0.0587 (8)
H21	1.3126	0.7864	−0.0224	0.070*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0456 (10)	0.0342 (9)	0.0435 (10)	−0.0048 (8)	0.0178 (8)	0.0015 (8)
O2	0.0535 (12)	0.0559 (12)	0.0508 (11)	−0.0077 (10)	0.0171 (10)	−0.0018 (10)
O3	0.101 (2)	0.085 (2)	0.0768 (18)	−0.0286 (18)	0.0309 (15)	0.0115 (15)
O4	0.0422 (10)	0.0337 (10)	0.0598 (11)	−0.0029 (8)	0.0218 (9)	0.0005 (9)
O5	0.0492 (13)	0.0593 (16)	0.121 (2)	0.0022 (12)	0.0392 (14)	0.0042 (15)
O6	0.0462 (11)	0.0442 (10)	0.0462 (10)	0.0045 (9)	0.0162 (8)	0.0099 (8)
O7	0.0768 (17)	0.0592 (15)	0.0691 (15)	−0.0078 (13)	0.0330 (13)	0.0151 (13)
O8	0.0454 (11)	0.0481 (11)	0.0502 (11)	−0.0016 (9)	0.0177 (9)	−0.0086 (9)
O9	0.102 (2)	0.109 (3)	0.097 (2)	0.049 (2)	0.0209 (18)	−0.0315 (19)
O10	0.0459 (10)	0.0294 (9)	0.0559 (11)	0.0004 (8)	0.0257 (9)	0.0009 (8)
O11	0.0760 (18)	0.0810 (19)	0.0855 (19)	−0.0344 (15)	0.0361 (15)	−0.0012 (15)
C1	0.0399 (13)	0.0320 (12)	0.0432 (13)	−0.0019 (10)	0.0176 (11)	0.0001 (11)
C2	0.0402 (14)	0.0360 (13)	0.0427 (13)	0.0008 (11)	0.0167 (11)	−0.0013 (11)
C3	0.0367 (13)	0.0387 (13)	0.0478 (14)	0.0010 (11)	0.0197 (11)	0.0035 (12)
C4	0.0374 (13)	0.0300 (12)	0.0521 (15)	−0.0012 (11)	0.0166 (11)	0.0027 (11)
C5	0.0399 (14)	0.0329 (13)	0.0465 (14)	−0.0001 (11)	0.0195 (11)	0.0010 (11)
C6	0.0526 (17)	0.0426 (15)	0.0540 (17)	−0.0005 (13)	0.0216 (14)	−0.0051 (13)
C7	0.086 (3)	0.0523 (19)	0.0521 (18)	−0.0007 (18)	0.0236 (18)	−0.0051 (15)
C8	0.099 (3)	0.102 (3)	0.063 (2)	0.017 (3)	0.006 (2)	0.004 (2)
C9	0.0444 (16)	0.0487 (18)	0.070 (2)	−0.0114 (15)	0.0227 (14)	−0.0075 (16)
C10	0.078 (3)	0.049 (2)	0.105 (3)	−0.0242 (19)	0.039 (2)	0.005 (2)
C11	0.068 (2)	0.0462 (17)	0.0481 (16)	0.0011 (15)	0.0168 (15)	0.0058 (14)
C12	0.089 (3)	0.079 (3)	0.088 (3)	0.020 (2)	0.018 (2)	0.032 (2)
C13	0.070 (2)	0.0432 (17)	0.0644 (19)	0.0026 (16)	0.0339 (17)	−0.0080 (15)
C14	0.096 (3)	0.090 (3)	0.077 (2)	−0.037 (3)	0.041 (2)	−0.036 (2)
C15	0.0365 (13)	0.0345 (13)	0.0379 (13)	−0.0017 (10)	0.0108 (10)	0.0020 (10)
C16	0.0446 (15)	0.0302 (13)	0.0559 (17)	−0.0023 (11)	0.0148 (13)	−0.0053 (12)
C17	0.0479 (16)	0.0354 (14)	0.0534 (16)	−0.0104 (12)	0.0132 (13)	−0.0016 (12)
C18	0.0395 (13)	0.0463 (16)	0.0408 (13)	−0.0058 (12)	0.0125 (11)	0.0022 (12)
C19	0.0489 (16)	0.0406 (15)	0.0530 (16)	0.0063 (13)	0.0210 (13)	0.0013 (12)
C20	0.0501 (15)	0.0312 (13)	0.0568 (16)	0.0019 (12)	0.0230 (13)	0.0011 (12)
C21	0.0525 (18)	0.070 (2)	0.0581 (18)	−0.0109 (17)	0.0212 (15)	0.0046 (17)

Geometric parameters (Å, º) top

O1—C1	1.409 (3)	C7—C8	1.474 (6)
O1—C5	1.441 (3)	C8—H8A	0.9600
O2—C7	1.356 (4)	C8—H8B	0.9600
O2—C6	1.435 (4)	C8—H8C	0.9600
O3—C7	1.201 (5)	C9—C10	1.500 (5)
O4—C9	1.369 (4)	C10—H10A	0.9600
O4—C4	1.441 (3)	C10—H10B	0.9600
O5—C9	1.184 (4)	C10—H10C	0.9600
O6—C11	1.356 (4)	C11—C12	1.494 (5)
O6—C3	1.441 (4)	C12—H12A	0.9600
O7—C11	1.189 (4)	C12—H12B	0.9600
O8—C13	1.347 (4)	C12—H12C	0.9600
O8—C2	1.435 (3)	C13—C14	1.484 (5)
O9—C13	1.185 (5)	C14—H14A	0.9600
O10—C15	1.372 (3)	C14—H14B	0.9600
O10—C1	1.411 (3)	C14—H14C	0.9600
O11—C21	1.188 (5)	C15—C16	1.387 (4)
C1—C2	1.529 (3)	C15—C20	1.391 (4)
C1—H1	0.9800	C16—C17	1.377 (4)
C2—C3	1.524 (4)	C16—H16	0.9300
C2—H2	0.9800	C17—C18	1.382 (4)
C3—C4	1.519 (4)	C17—H17	0.9300
C3—H3	0.9800	C18—C19	1.389 (4)
C4—C5	1.528 (3)	C18—C21	1.479 (4)
C4—H4	0.9800	C19—C20	1.388 (4)
C5—C6	1.497 (4)	C19—H19	0.9300
C5—H5	0.9800	C20—H20	0.9300
C6—H6A	0.9700	C21—H21	0.9300
C6—H6B	0.9700

C1—O1—C5	113.85 (19)	H8B—C8—H8C	109.5
C7—O2—C6	117.3 (3)	O5—C9—O4	122.9 (3)
C9—O4—C4	115.1 (2)	O5—C9—C10	126.4 (3)
C11—O6—C3	116.5 (2)	O4—C9—C10	110.7 (3)
C13—O8—C2	117.4 (2)	C9—C10—H10A	109.5
C15—O10—C1	118.5 (2)	C9—C10—H10B	109.5
O1—C1—O10	106.5 (2)	H10A—C10—H10B	109.5
O1—C1—C2	109.2 (2)	C9—C10—H10C	109.5
O10—C1—C2	105.9 (2)	H10A—C10—H10C	109.5
O1—C1—H1	111.7	H10B—C10—H10C	109.5
O10—C1—H1	111.7	O7—C11—O6	124.5 (3)
C2—C1—H1	111.7	O7—C11—C12	125.8 (3)
O8—C2—C3	110.5 (2)	O6—C11—C12	109.7 (3)
O8—C2—C1	107.0 (2)	C11—C12—H12A	109.5
C3—C2—C1	111.0 (2)	C11—C12—H12B	109.5
O8—C2—H2	109.4	H12A—C12—H12B	109.5
C3—C2—H2	109.4	C11—C12—H12C	109.5
C1—C2—H2	109.4	H12A—C12—H12C	109.5
O6—C3—C4	108.2 (2)	H12B—C12—H12C	109.5
O6—C3—C2	107.6 (2)	O9—C13—O8	121.5 (3)
C4—C3—C2	109.0 (2)	O9—C13—C14	126.2 (3)
O6—C3—H3	110.7	O8—C13—C14	112.2 (3)
C4—C3—H3	110.7	C13—C14—H14A	109.5
C2—C3—H3	110.7	C13—C14—H14B	109.5
O4—C4—C3	109.9 (2)	H14A—C14—H14B	109.5
O4—C4—C5	108.1 (2)	C13—C14—H14C	109.5
C3—C4—C5	110.7 (2)	H14A—C14—H14C	109.5
O4—C4—H4	109.3	H14B—C14—H14C	109.5
C3—C4—H4	109.3	O10—C15—C16	115.4 (2)
C5—C4—H4	109.3	O10—C15—C20	124.1 (2)
O1—C5—C6	108.0 (2)	C16—C15—C20	120.5 (2)
O1—C5—C4	105.6 (2)	C17—C16—C15	120.0 (3)
C6—C5—C4	115.9 (2)	C17—C16—H16	120.0
O1—C5—H5	109.0	C15—C16—H16	120.0
C6—C5—H5	109.0	C16—C17—C18	120.5 (3)
C4—C5—H5	109.0	C16—C17—H17	119.8
O2—C6—C5	112.4 (2)	C18—C17—H17	119.8
O2—C6—H6A	109.1	C17—C18—C19	119.2 (3)
C5—C6—H6A	109.1	C17—C18—C21	122.7 (3)
O2—C6—H6B	109.1	C19—C18—C21	118.0 (3)
C5—C6—H6B	109.1	C20—C19—C18	121.2 (3)
H6A—C6—H6B	107.8	C20—C19—H19	119.4
O3—C7—O2	122.4 (4)	C18—C19—H19	119.4
O3—C7—C8	125.6 (4)	C19—C20—C15	118.6 (3)
O2—C7—C8	111.9 (4)	C19—C20—H20	120.7
C7—C8—H8A	109.5	C15—C20—H20	120.7
C7—C8—H8B	109.5	O11—C21—C18	125.6 (4)
H8A—C8—H8B	109.5	O11—C21—H21	117.2
C7—C8—H8C	109.5	C18—C21—H21	117.2
H8A—C8—H8C	109.5

C5—O1—C1—O10	−177.44 (19)	C3—C4—C5—C6	179.7 (2)
C5—O1—C1—C2	−63.6 (3)	C7—O2—C6—C5	104.7 (3)
C15—O10—C1—O1	−76.9 (3)	O1—C5—C6—O2	−68.4 (3)
C15—O10—C1—C2	167.0 (2)	C4—C5—C6—O2	49.8 (3)
C13—O8—C2—C3	−101.7 (3)	C6—O2—C7—O3	−6.0 (5)
C13—O8—C2—C1	137.3 (2)	C6—O2—C7—C8	173.2 (3)
O1—C1—C2—O8	175.1 (2)	C4—O4—C9—O5	6.4 (5)
O10—C1—C2—O8	−70.7 (3)	C4—O4—C9—C10	−171.0 (3)
O1—C1—C2—C3	54.4 (3)	C3—O6—C11—O7	−4.2 (5)
O10—C1—C2—C3	168.6 (2)	C3—O6—C11—C12	176.3 (3)
C11—O6—C3—C4	−94.4 (3)	C2—O8—C13—O9	2.7 (5)
C11—O6—C3—C2	148.0 (2)	C2—O8—C13—C14	−179.5 (3)
O8—C2—C3—O6	−53.2 (3)	C1—O10—C15—C16	−174.9 (2)
C1—C2—C3—O6	65.4 (3)	C1—O10—C15—C20	5.6 (4)
O8—C2—C3—C4	−170.2 (2)	O10—C15—C16—C17	179.6 (2)
C1—C2—C3—C4	−51.7 (3)	C20—C15—C16—C17	−0.8 (4)
C9—O4—C4—C3	78.4 (3)	C15—C16—C17—C18	−1.1 (4)
C9—O4—C4—C5	−160.6 (2)	C16—C17—C18—C19	1.5 (4)
O6—C3—C4—O4	58.7 (2)	C16—C17—C18—C21	−177.5 (3)
C2—C3—C4—O4	175.4 (2)	C17—C18—C19—C20	0.0 (4)
O6—C3—C4—C5	−60.7 (3)	C21—C18—C19—C20	179.1 (3)
C2—C3—C4—C5	56.0 (3)	C18—C19—C20—C15	−1.9 (4)
C1—O1—C5—C6	−169.3 (2)	O10—C15—C20—C19	−178.2 (3)
C1—O1—C5—C4	66.1 (3)	C16—C15—C20—C19	2.3 (4)
O4—C4—C5—O1	178.8 (2)	C17—C18—C21—O11	−1.5 (5)
C3—C4—C5—O1	−60.7 (3)	C19—C18—C21—O11	179.4 (3)
O4—C4—C5—C6	59.3 (3)

Experimental details

Crystal data
Chemical formula	C₂₁H₂₄O₁₁
M_r	452.40
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	291
a, b, c (Å)	7.056 (4), 17.758 (6), 9.129 (3)
β (°)	102.80 (4)
V (Å³)	1115.4 (8)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.11
Crystal size (mm)	0.44 × 0.42 × 0.20

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	4596, 4149, 2143
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.756

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.050, 0.143, 0.95
No. of reflections	4149
No. of parameters	293
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.30, −0.20

Computer programs: DIFRAC (Gabe & White, 1993), DIFRAC (Gabe et al., 1989), NRCVAX (Gabe et al., 1989), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997).

Acknowledgements

The authors thank Mr Zhi-Hua Mao of Sichuan University for the data collection.

References

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