2-(4-Methoxyphenoxy)-6-methyl-3-oxo-3,6-dihydro-2H-pyran-4-yl benzoate

Yan, S.; Liang, X.; Zhang, J.; Wang, D.

doi:10.1107/S1600536809004231

organic compounds

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ISSN: 2056-9890

Volume 65| Part 3| March 2009| Page o586

doi:10.1107/S1600536809004231

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2-(4-Methoxyphenoxy)-6-methyl-3-oxo-3,6-dihydro-2H-pyran-4-yl benzoate

Shi-qiang Yan,^a Xiao-mei Liang,^a Jian-jun Zhang ^a ^* and Dao-quan Wang ^a

^aDepartment of Applied Chemistry, China Agricultural University, Beijing 100193, People's Republic of China
^*Correspondence e-mail: zhangjianjun@cau.edu.cn

(Received 30 November 2008; accepted 5 February 2009; online 25 February 2009)

The title compound, C₂₀H₁₈O₆, has been synthesized from 4-methoxyphenyl 3-O-benzoyloxy-α-L-rhamnopyranoside by oxidation on treatment with pyridinium dichromate in the presence of acetic anhydride. In the molecule, the pyran ring adopts an envelope conformation with the O atom at the flap position. Weak intermolecular C—H⋯O hydrogen bonding is present in the crystal structure.

Related literature

For general background to enolone derivatives, see: Schmidt et al. (1954 ); Hodges et al. (1963 ); Bevan et al. (1963 ); Ripperger & Seifert (1975 ); Yan et al. (2008 ).

Experimental

Crystal data

C₂₀H₁₈O₆
M_r = 354.34
Orthorhombic, P 2₁ 2₁ 2₁
a = 8.5906 (17) Å
b = 11.594 (2) Å
c = 17.404 (4) Å
V = 1733.4 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 173 (2) K
0.80 × 0.72 × 0.40 mm

Data collection

Rigaku R-Axis Rapid IP are-detector diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ) T_min = 0.924, T_max = 0.961
3953 measured reflections
2262 independent reflections
1752 reflections with I > 2σ(I)
R_int = 0.015

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.055
S = 0.87
2262 reflections
236 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C15—H15A⋯O6ⁱ	0.95	2.42	3.343 (2)	163
Symmetry code: (i) $[-x+3, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Data collection: RAPID-AUTO (Rigaku, 2001 ); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809004231/xu2467sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809004231/xu2467Isup2.hkl

checkCIF report

Comment top

The enolone structural unit is often present in nature products, such as brevifolic acid, a constituent of the ellagitannins (Schmidt et al., 1954), meliacinslike cedrelone and anthothecol (Hodges et al., 1963; Bevan et al., 1963) or triterpenoids of the elaterin type, which are widely distributed in cucurbitaceous and cruciferous plants (Ripperger & Seifert, 1975). In a continuation of our search for alcohol oxidation (Yan et al., 2008), herein we present the crystal structure of the title compound, which was produced by oxidation with PDC and acetic anhydride.

In the molecule of the title compound (Fig. 1), the pyran ring conformation can be described as an envelope, with C1/C2/C3/C4/C5 lying almost on the same plane and O1 deviating from this mean plane. The terminal benzene rings of the molecule are nearly perpendicular to each other with a dihedral angle of 83.6 (1)°. The weak intermolecular C—H···O hydrogen bonding presents in the crystal structure (Table 1).

Related literature top

For general background to enolone derivatives, see: Schmidt et al. (1954); Hodges et al. (1963); Bevan et al. (1963); Ripperger et al. (1975); Yan et al. (2008).

Experimental top

A mixture of 4-methoxyphenyl 3-O-benzoyloxy-a-L-rhamnopyranoside (3.74 g, 10 mmol), pyridinium dichromate (4.60 g, 12 mmol), and acetic anhydride (5.68 ml, 60 mmol) in CH₂Cl₂ (40 ml) was stirred at reflux for 8 h, at the end of which time TLC (4:1 petroleumether–EtOAc) indicated that the reaction was complete. After direct concentration of the reaction mixture, the dark brown residue was diluted with EtOAc (60 ml) and the solution was passed through a short (5–10 cm) silica-gel column. The column was eluted with EtOAc and the eluents were concentrated and coevaporated with toluene. The residue was subjected to silica-gel column chromatography again (4:1 petroleum ether–EtOAc) to give the title compound (2.48 g, 70%). Single crystals suitable for X-ray measurements were obtained by recrystallization from 8:1 petroleumether–EtOAc at room temperature.

Computing details top

Data collection: RAPID-AUTO (Rigaku, 2001); cell refinement: RAPID-AUTO (Rigaku, 2001); data reduction: RAPID-AUTO (Rigaku, 2001); 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 (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of the title compound, showing the atomic labelling and displacement ellipsoids drawn at the 50% probability level.

2-(4-Methoxyphenoxy)-6-methyl-3-oxo-3,6-dihydro-2H-pyran-4-yl benzoate top

Crystal data top

C₂₀H₁₈O₆	F(000) = 744
M_r = 354.34	D_x = 1.358 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 789 reflections
a = 8.5906 (17) Å	θ = 2.2–27.5°
b = 11.594 (2) Å	µ = 0.10 mm⁻¹
c = 17.404 (4) Å	T = 173 K
V = 1733.4 (6) Å³	Block, colorless
Z = 4	0.80 × 0.72 × 0.40 mm

Data collection top

Rigaku R-Axis Rapid IP are-detector diffractometer	2262 independent reflections
Radiation source: rotating anode	1752 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.015
ω scan	θ_max = 27.4°, θ_min = 2.1°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −11→11
T_min = 0.924, T_max = 0.961	k = −14→15
3953 measured reflections	l = −22→22

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)] = 0.034	H-atom parameters constrained
wR(F²) = 0.055	w = 1/[σ²(F_o²)]
S = 0.87	(Δ/σ)_max = 0.001
2262 reflections	Δρ_max = 0.17 e Å⁻³
236 parameters	Δρ_min = −0.24 e Å⁻³
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0215 (13)

Crystal data top

C₂₀H₁₈O₆	V = 1733.4 (6) Å³
M_r = 354.34	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 8.5906 (17) Å	µ = 0.10 mm⁻¹
b = 11.594 (2) Å	T = 173 K
c = 17.404 (4) Å	0.80 × 0.72 × 0.40 mm

Data collection top

Rigaku R-Axis Rapid IP are-detector diffractometer	2262 independent reflections
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	1752 reflections with I > 2σ(I)
T_min = 0.924, T_max = 0.961	R_int = 0.015
3953 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	0 restraints
wR(F²) = 0.055	H-atom parameters constrained
S = 0.87	Δρ_max = 0.17 e Å⁻³
2262 reflections	Δρ_min = −0.24 e Å⁻³
236 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	1.17184 (15)	0.59200 (11)	0.94630 (8)	0.0262 (4)
O2	0.93224 (17)	0.89681 (11)	0.91264 (8)	0.0298 (4)
O3	1.04268 (19)	0.94639 (12)	1.02536 (9)	0.0370 (4)
O4	1.21198 (18)	0.84659 (12)	0.84053 (9)	0.0372 (4)
O5	1.13746 (15)	0.59345 (11)	0.81269 (7)	0.0230 (3)
O6	1.36640 (18)	0.16881 (11)	0.72242 (9)	0.0371 (4)
C1	1.0087 (2)	0.58644 (17)	0.96426 (13)	0.0278 (5)
H1A	0.9575	0.5302	0.9288	0.033*
C2	0.9327 (3)	0.70107 (17)	0.95530 (12)	0.0290 (5)
H2A	0.8318	0.7123	0.9763	0.035*
C3	1.0009 (3)	0.78794 (17)	0.91900 (12)	0.0257 (5)
C4	1.1459 (2)	0.77091 (16)	0.87611 (12)	0.0250 (5)
C5	1.2071 (2)	0.64760 (16)	0.87719 (11)	0.0236 (5)
H5A	1.3226	0.6488	0.8701	0.028*
C6	0.9976 (3)	0.5411 (2)	1.04592 (14)	0.0425 (6)
H6A	1.0486	0.4657	1.0491	0.064*
H6B	0.8878	0.5333	1.0604	0.064*
H6C	1.0491	0.5952	1.0810	0.064*
C7	0.9639 (2)	0.97192 (17)	0.97094 (13)	0.0251 (5)
C8	0.8888 (2)	1.08488 (16)	0.95760 (12)	0.0230 (5)
C9	0.8571 (3)	1.15548 (17)	1.02010 (13)	0.0304 (5)
H9A	0.8852	1.1316	1.0705	0.037*
C10	0.7844 (3)	1.26088 (18)	1.00880 (15)	0.0379 (6)
H10A	0.7621	1.3092	1.0515	0.045*
C11	0.7445 (3)	1.29565 (18)	0.93534 (14)	0.0384 (6)
H11A	0.6946	1.3679	0.9277	0.046*
C12	0.7767 (3)	1.22605 (17)	0.87332 (14)	0.0340 (6)
H12A	0.7498	1.2507	0.8230	0.041*
C13	0.8478 (2)	1.12062 (16)	0.88406 (12)	0.0278 (5)
H13A	0.8687	1.0724	0.8412	0.033*
C14	1.1981 (2)	0.48407 (16)	0.79498 (10)	0.0203 (5)
C15	1.3486 (2)	0.47295 (16)	0.76804 (11)	0.0242 (5)
H15A	1.4147	0.5385	0.7652	0.029*
C16	1.4024 (2)	0.36583 (16)	0.74524 (12)	0.0260 (5)
H16A	1.5060	0.3573	0.7271	0.031*
C17	1.3043 (2)	0.27089 (16)	0.74899 (12)	0.0247 (5)
C18	1.1540 (3)	0.28231 (17)	0.77601 (12)	0.0278 (5)
H18A	1.0869	0.2173	0.7784	0.033*
C19	1.1018 (2)	0.39045 (16)	0.79972 (11)	0.0260 (5)
H19A	0.9992	0.3991	0.8192	0.031*
C20	1.2665 (3)	0.07108 (16)	0.72123 (15)	0.0446 (7)
H20A	1.3233	0.0044	0.7010	0.067*
H20B	1.1765	0.0871	0.6883	0.067*
H20C	1.2307	0.0544	0.7735	0.067*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0262 (8)	0.0268 (8)	0.0256 (8)	0.0052 (7)	−0.0006 (6)	0.0013 (7)
O2	0.0395 (9)	0.0208 (8)	0.0292 (8)	0.0097 (7)	−0.0036 (7)	−0.0066 (7)
O3	0.0455 (10)	0.0285 (9)	0.0370 (10)	0.0032 (7)	−0.0157 (8)	−0.0016 (7)
O4	0.0356 (10)	0.0274 (8)	0.0486 (10)	−0.0030 (8)	0.0019 (8)	0.0054 (8)
O5	0.0236 (8)	0.0212 (7)	0.0244 (7)	0.0041 (7)	−0.0024 (6)	−0.0035 (6)
O6	0.0275 (9)	0.0231 (8)	0.0607 (11)	0.0022 (7)	−0.0003 (9)	−0.0118 (8)
C1	0.0272 (12)	0.0244 (12)	0.0319 (12)	0.0035 (10)	0.0030 (10)	0.0004 (10)
C2	0.0276 (12)	0.0339 (13)	0.0255 (12)	0.0059 (10)	0.0044 (10)	−0.0026 (10)
C3	0.0294 (13)	0.0236 (11)	0.0242 (11)	0.0062 (10)	−0.0048 (10)	−0.0063 (10)
C4	0.0274 (13)	0.0233 (11)	0.0244 (11)	−0.0013 (10)	−0.0071 (10)	−0.0039 (10)
C5	0.0199 (11)	0.0251 (11)	0.0258 (11)	0.0026 (9)	−0.0010 (10)	−0.0013 (10)
C6	0.0481 (15)	0.0426 (14)	0.0367 (14)	0.0099 (13)	0.0097 (12)	0.0110 (12)
C7	0.0249 (12)	0.0227 (11)	0.0278 (12)	−0.0028 (10)	0.0029 (10)	−0.0022 (10)
C8	0.0196 (11)	0.0199 (11)	0.0295 (12)	−0.0031 (9)	0.0026 (9)	−0.0009 (9)
C9	0.0358 (14)	0.0268 (12)	0.0287 (12)	−0.0022 (11)	0.0055 (11)	−0.0010 (10)
C10	0.0484 (16)	0.0218 (11)	0.0434 (15)	0.0026 (12)	0.0142 (13)	−0.0060 (11)
C11	0.0384 (15)	0.0229 (12)	0.0540 (17)	0.0059 (11)	0.0116 (13)	0.0059 (11)
C12	0.0355 (14)	0.0283 (13)	0.0382 (14)	0.0017 (11)	0.0016 (12)	0.0096 (11)
C13	0.0284 (12)	0.0262 (12)	0.0288 (12)	−0.0008 (10)	0.0030 (10)	−0.0023 (10)
C14	0.0229 (12)	0.0194 (10)	0.0185 (10)	0.0038 (9)	−0.0009 (9)	−0.0022 (8)
C15	0.0235 (12)	0.0207 (10)	0.0284 (12)	−0.0047 (10)	0.0006 (10)	0.0005 (9)
C16	0.0170 (11)	0.0284 (12)	0.0326 (12)	0.0022 (9)	0.0041 (10)	−0.0016 (10)
C17	0.0243 (13)	0.0214 (11)	0.0285 (12)	0.0056 (9)	−0.0048 (10)	−0.0028 (9)
C18	0.0236 (12)	0.0232 (11)	0.0367 (13)	−0.0053 (10)	0.0011 (11)	−0.0004 (10)
C19	0.0212 (12)	0.0280 (12)	0.0287 (12)	0.0001 (10)	0.0040 (9)	−0.0019 (10)
C20	0.0363 (15)	0.0194 (11)	0.0782 (19)	0.0025 (11)	−0.0133 (14)	−0.0114 (12)

Geometric parameters (Å, º) top

O1—C5	1.398 (2)	C8—C13	1.391 (3)
O1—C1	1.437 (2)	C9—C10	1.386 (3)
O2—C7	1.365 (2)	C9—H9A	0.9500
O2—C3	1.398 (2)	C10—C11	1.384 (3)
O3—C7	1.201 (2)	C10—H10A	0.9500
O4—C4	1.215 (2)	C11—C12	1.376 (3)
O5—C14	1.405 (2)	C11—H11A	0.9500
O5—C5	1.418 (2)	C12—C13	1.379 (3)
O6—C17	1.378 (2)	C12—H12A	0.9500
O6—C20	1.422 (2)	C13—H13A	0.9500
C1—C2	1.489 (3)	C14—C19	1.367 (3)
C1—C6	1.518 (3)	C14—C15	1.381 (3)
C1—H1A	1.0000	C15—C16	1.383 (3)
C2—C3	1.326 (3)	C15—H15A	0.9500
C2—H2A	0.9500	C16—C17	1.387 (3)
C3—C4	1.465 (3)	C16—H16A	0.9500
C4—C5	1.523 (3)	C17—C18	1.381 (3)
C5—H5A	1.0000	C18—C19	1.394 (3)
C6—H6A	0.9800	C18—H18A	0.9500
C6—H6B	0.9800	C19—H19A	0.9500
C6—H6C	0.9800	C20—H20A	0.9800
C7—C8	1.478 (3)	C20—H20B	0.9800
C8—C9	1.388 (3)	C20—H20C	0.9800

C5—O1—C1	114.77 (15)	C10—C9—H9A	120.1
C7—O2—C3	115.67 (16)	C8—C9—H9A	120.1
C14—O5—C5	114.64 (14)	C11—C10—C9	120.0 (2)
C17—O6—C20	117.11 (17)	C11—C10—H10A	120.0
O1—C1—C2	111.40 (17)	C9—C10—H10A	120.0
O1—C1—C6	106.29 (18)	C12—C11—C10	120.3 (2)
C2—C1—C6	112.29 (19)	C12—C11—H11A	119.9
O1—C1—H1A	108.9	C10—C11—H11A	119.9
C2—C1—H1A	108.9	C11—C12—C13	120.2 (2)
C6—C1—H1A	108.9	C11—C12—H12A	119.9
C3—C2—C1	122.3 (2)	C13—C12—H12A	119.9
C3—C2—H2A	118.9	C12—C13—C8	120.1 (2)
C1—C2—H2A	118.9	C12—C13—H13A	120.0
C2—C3—O2	122.5 (2)	C8—C13—H13A	120.0
C2—C3—C4	121.08 (19)	C19—C14—C15	120.83 (18)
O2—C3—C4	116.11 (18)	C19—C14—O5	118.64 (18)
O4—C4—C3	124.03 (19)	C15—C14—O5	120.37 (17)
O4—C4—C5	121.5 (2)	C14—C15—C16	119.60 (18)
C3—C4—C5	114.42 (18)	C14—C15—H15A	120.2
O1—C5—O5	112.68 (15)	C16—C15—H15A	120.2
O1—C5—C4	111.63 (17)	C15—C16—C17	119.73 (19)
O5—C5—C4	105.08 (15)	C15—C16—H16A	120.1
O1—C5—H5A	109.1	C17—C16—H16A	120.1
O5—C5—H5A	109.1	O6—C17—C18	123.95 (19)
C4—C5—H5A	109.1	O6—C17—C16	115.51 (19)
C1—C6—H6A	109.5	C18—C17—C16	120.52 (18)
C1—C6—H6B	109.5	C17—C18—C19	119.18 (19)
H6A—C6—H6B	109.5	C17—C18—H18A	120.4
C1—C6—H6C	109.5	C19—C18—H18A	120.4
H6A—C6—H6C	109.5	C14—C19—C18	120.1 (2)
H6B—C6—H6C	109.5	C14—C19—H19A	119.9
O3—C7—O2	122.79 (19)	C18—C19—H19A	119.9
O3—C7—C8	126.03 (19)	O6—C20—H20A	109.5
O2—C7—C8	111.18 (18)	O6—C20—H20B	109.5
C9—C8—C13	119.72 (19)	H20A—C20—H20B	109.5
C9—C8—C7	119.00 (19)	O6—C20—H20C	109.5
C13—C8—C7	121.27 (18)	H20A—C20—H20C	109.5
C10—C9—C8	119.8 (2)	H20B—C20—H20C	109.5

C5—O1—C1—C2	−48.6 (2)	O3—C7—C8—C13	157.1 (2)
C5—O1—C1—C6	−171.17 (16)	O2—C7—C8—C13	−23.2 (3)
O1—C1—C2—C3	14.0 (3)	C13—C8—C9—C10	0.2 (3)
C6—C1—C2—C3	133.1 (2)	C7—C8—C9—C10	−179.0 (2)
C1—C2—C3—O2	−177.84 (19)	C8—C9—C10—C11	−0.3 (3)
C1—C2—C3—C4	8.9 (3)	C9—C10—C11—C12	0.0 (4)
C7—O2—C3—C2	89.0 (2)	C10—C11—C12—C13	0.6 (4)
C7—O2—C3—C4	−97.4 (2)	C11—C12—C13—C8	−0.7 (3)
C2—C3—C4—O4	178.5 (2)	C9—C8—C13—C12	0.3 (3)
O2—C3—C4—O4	4.8 (3)	C7—C8—C13—C12	179.49 (19)
C2—C3—C4—C5	0.3 (3)	C5—O5—C14—C19	116.7 (2)
O2—C3—C4—C5	−173.41 (17)	C5—O5—C14—C15	−67.9 (2)
C1—O1—C5—O5	−59.9 (2)	C19—C14—C15—C16	0.3 (3)
C1—O1—C5—C4	58.1 (2)	O5—C14—C15—C16	−174.99 (17)
C14—O5—C5—O1	−68.5 (2)	C14—C15—C16—C17	0.6 (3)
C14—O5—C5—C4	169.78 (16)	C20—O6—C17—C18	1.8 (3)
O4—C4—C5—O1	149.13 (18)	C20—O6—C17—C16	−176.5 (2)
C3—C4—C5—O1	−32.6 (2)	C15—C16—C17—O6	177.71 (17)
O4—C4—C5—O5	−88.4 (2)	C15—C16—C17—C18	−0.6 (3)
C3—C4—C5—O5	89.8 (2)	O6—C17—C18—C19	−178.37 (19)
C3—O2—C7—O3	−1.6 (3)	C16—C17—C18—C19	−0.2 (3)
C3—O2—C7—C8	178.67 (17)	C15—C14—C19—C18	−1.1 (3)
O3—C7—C8—C9	−23.8 (3)	O5—C14—C19—C18	174.26 (17)
O2—C7—C8—C9	155.93 (18)	C17—C18—C19—C14	1.0 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C15—H15A···O6ⁱ	0.95	2.42	3.343 (2)	163

Symmetry code: (i) −x+3, y+1/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	C₂₀H₁₈O₆
M_r	354.34
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	173
a, b, c (Å)	8.5906 (17), 11.594 (2), 17.404 (4)
V (Å³)	1733.4 (6)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.80 × 0.72 × 0.40

Data collection
Diffractometer	Rigaku R-Axis Rapid IP are-detector diffractometer
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995)
T_min, T_max	0.924, 0.961
No. of measured, independent and observed [I > 2σ(I)] reflections	3953, 2262, 1752
R_int	0.015
(sin θ/λ)_max (Å⁻¹)	0.648

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.055, 0.87
No. of reflections	2262
No. of parameters	236
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.17, −0.24

Computer programs: RAPID-AUTO (Rigaku, 2001), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C15—H15A···O6ⁱ	0.95	2.42	3.343 (2)	163

Symmetry code: (i) −x+3, y+1/2, −z+3/2.

Acknowledgements

The authors thank the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry (No. 21168020) and the Doctoral Program Foundation of Institutions of Higher Education of China (No. 20070019072) for support.

References

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