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Acta Cryst. (2009). E65, o2146    [ doi:10.1107/S1600536809031183 ]

5,7-Dimethoxyisobenzofuran-1(3H)-one

M.-X. Sun, X. Li, W.-Y. Liu and K. Xiao

Abstract top

The asymmetric unit of the title compound, C10H10O4, which has been isolated from rhizoma Polygonum Cuspidatum, a Chinese folk medicine, contains two crystallographically independent molecules. The molecules are essentially planar, with a maximum deviation of 0.061 (2) Å from the best planes. The crystal packing is stabilized by weak intermolecular C-H...O hydrogen-bonding interactions, with a stacking direction of the molecules parallel to [101].

Comment top

The compound 5, 7-dimethoxyphthalide has been previously reported. It could be obtained by different synthetic strategies, e.g. from 5,7-dihydroxyphthalide (Talapatra & Monoj, 1980), 6-iodo-3-methoxybenzyl alcohols (Dang et al., 1999) or 3,5-dimethoxybenzyl alcohol (Orito et al.,1995). It could act as an intermediate product in the process of synthesizing some significant compounds, such as 5,7-dimethoxy-4-methylphthalide and 5,7-dihydroxy-4-methylphthaIide (Zuo et al., 2008), or mycophenolic acid and its analogs (Lee et al., 2001). It was also reported as a byproduct in the synthesis of zearalenone and lasiodiplodin (Fürstner et al., 2000). However, no structural details were provided. In this study, 5,7-dimethoxyphthalide was isolated from the rhizoma Polygonum cuspidatum as colorless prismatic crystals.

The molecule (Fig. 1 ) is essentially planar with a maximum deviation of 0.061 (2) Å from the best planes. The crystal packing is stabilized by weak intermolecular C—H···O hydrogen-bonding interactions with a stacking direction of the molecules parallel to [101] (Fig. 2 ).

Related literature top

For the synthesis of 5,7-dimethoxyphthalide, see: Talapatra & Monoj (1980); Dang et al. (1999); Orito et al. (1995). For the title compound as an intermediate product, see: Zuo et al. (2008); Lee et al. (2001). For the title compound as a byproduct, see: Fürstner et al. (2000).

Experimental top

The slices of the dried roots of P. cuspidatum (10 kg) were extracted with 60% aqueous acetone 3 times (24 h each) at room temperature. The solvent was evaporated in vacuo and some hydrophobic substances precipitated which were filtered off. The filtrate was concentrated to a suitable volume, then chromatographed on a Sephadex LH-20 column eluted with H2O, aqueous MeOH (10%-70%) and 50% acetone successively to give five fractions. The fraction eluated by 10% MeOH was subjected to MCI gel chromatography eluted with gradient aqueous MeOH solvent. The 30% aqueous MeOH eluate from the MCI column afforded the compound 5,7-dimethoxyphthalide as an amorphous powder. The powder was recrystallized in acetone and produced colourless prismatic crystals.

Refinement top

The H atoms were refined at calculated positions riding on the parent carbon atoms (C–H = 0.95–0.99 Å) with isotropic displacement parameters Uiso(H) = 1.2U(Ceq) or 1.5U(–CH3). All CH3 hydrogen atoms were allowed to rotate but not to tip.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); 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) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of 5,7-dimethoxyphthalide, showing the atom-labelling scheme. H atoms are shown as small spheres of arbitrary radius. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. Molecular packing in the crystal, viewed along the b axis. Dashed lines indicate intermolecular C—H···O hydrogen bonds.
5,7-Dimethoxyisobenzofuran-1(3H)-one top
Crystal data top
C10H10O4F(000) = 816
Mr = 194.18Dx = 1.440 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 715 reflections
a = 8.532 (3) Åθ = 2.6–21.3°
b = 25.877 (10) ŵ = 0.11 mm−1
c = 8.374 (3) ÅT = 293 K
β = 104.322 (6)°Prism, colourless
V = 1791.5 (11) Å30.12 × 0.12 × 0.10 mm
Z = 8
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer		3216 independent reflections
Radiation source: fine-focus sealed tube1766 reflections with I > 2σ(I)
graphiteRint = 0.062
φ and ω scansθmax = 25.2°, θmin = 1.6°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −7→10
Tmin = 0.987, Tmax = 0.989k = −30→31
7489 measured reflectionsl = −10→8
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.052H-atom parameters constrained
wR(F2) = 0.131 w = 1/[σ2(Fo2) + (0.053P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.93(Δ/σ)max < 0.001
3216 reflectionsΔρmax = 0.18 e Å−3
258 parametersΔρmin = −0.19 e Å−3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0026 (5)
Crystal data top
C10H10O4V = 1791.5 (11) Å3
Mr = 194.18Z = 8
Monoclinic, P21/cMo Kα radiation
a = 8.532 (3) ŵ = 0.11 mm−1
b = 25.877 (10) ÅT = 293 K
c = 8.374 (3) Å0.12 × 0.12 × 0.10 mm
β = 104.322 (6)°
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer		3216 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		1766 reflections with I > 2σ(I)
Tmin = 0.987, Tmax = 0.989Rint = 0.062
7489 measured reflectionsθmax = 25.2°
Refinement top
R[F2 > 2σ(F2)] = 0.052H-atom parameters constrained
wR(F2) = 0.131Δρmax = 0.18 e Å−3
S = 0.93Δρmin = −0.19 e Å−3
3216 reflectionsAbsolute structure: ?
258 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Experimental. The powder of 5,7-dimethoxyphthalide was solved in acetone and produced colorless crystal.

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
xyzUiso*/Ueq
O1A0.3975 (2)0.42391 (7)0.1615 (2)0.0627 (6)
O2A0.2605 (3)0.35976 (8)0.0110 (2)0.0674 (6)
O3A0.4002 (2)0.25798 (7)0.1709 (2)0.0571 (6)
O4A0.8571 (2)0.28610 (7)0.6142 (2)0.0628 (6)
C1A0.3670 (4)0.37248 (11)0.1270 (3)0.0518 (8)
C2A0.4830 (3)0.34270 (10)0.2496 (3)0.0417 (6)
C3A0.5069 (3)0.28902 (10)0.2724 (3)0.0470 (7)
C4A0.6341 (3)0.27237 (10)0.3971 (3)0.0471 (7)
H4A0.65290.23720.41410.057*
C5A0.7359 (3)0.30831 (11)0.4992 (3)0.0487 (7)
C6A0.7112 (3)0.36054 (10)0.4795 (3)0.0486 (7)
H6A0.77800.38420.54780.058*
C7A0.5835 (3)0.37640 (10)0.3545 (3)0.0452 (7)
C8A0.5296 (3)0.43027 (10)0.3046 (3)0.0542 (8)
H8A10.49420.44780.39200.065*
H8A20.61640.45000.27820.065*
C9A0.4125 (4)0.20351 (11)0.2069 (4)0.0644 (9)
H9A10.51770.19140.20250.097*
H9A20.33120.18530.12700.097*
H9A30.39680.19760.31500.097*
C10A0.9664 (4)0.31963 (13)0.7237 (4)0.0764 (10)
H10A1.02020.34150.66140.115*
H10B1.04510.29940.79990.115*
H10C0.90720.34060.78330.115*
O1B−0.0885 (2)0.46776 (7)0.6553 (2)0.0582 (5)
O2B−0.2380 (2)0.53224 (8)0.5190 (2)0.0674 (6)
O3B−0.0891 (2)0.63386 (7)0.6714 (2)0.0551 (5)
O4B0.3667 (2)0.60524 (7)1.1150 (2)0.0539 (5)
C1B−0.1230 (3)0.51938 (12)0.6263 (3)0.0522 (8)
C2B−0.0013 (3)0.54864 (11)0.7460 (3)0.0454 (7)
C3B0.0172 (3)0.60196 (10)0.7725 (3)0.0415 (7)
C4B0.1434 (3)0.61849 (10)0.8969 (3)0.0440 (7)
H4B0.15900.65370.91620.053*
C5B0.2488 (3)0.58354 (10)0.9954 (3)0.0420 (6)
C6B0.2297 (3)0.53046 (10)0.9714 (3)0.0418 (6)
H6B0.29880.50691.03750.050*
C7B0.1032 (3)0.51477 (9)0.8449 (3)0.0403 (6)
C8B0.0538 (3)0.46110 (10)0.7869 (3)0.0522 (7)
H8B10.13860.44420.74770.063*
H8B20.03020.44060.87500.063*
C9B−0.0723 (4)0.68778 (10)0.7035 (4)0.0620 (8)
H9B1−0.08630.69480.81170.093*
H9B2−0.15270.70620.62320.093*
H9B30.03350.69880.69730.093*
C10B0.4778 (3)0.57130 (11)1.2222 (3)0.0589 (8)
H10D0.41920.54851.27690.088*
H10E0.55310.59131.30280.088*
H10F0.53560.55141.15870.088*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O1A0.0734 (15)0.0519 (13)0.0597 (13)0.0139 (11)0.0105 (11)0.0112 (10)
O2A0.0663 (14)0.0782 (15)0.0517 (13)0.0101 (12)0.0029 (11)0.0066 (11)
O3A0.0585 (13)0.0487 (13)0.0580 (12)0.0039 (10)0.0028 (10)−0.0025 (10)
O4A0.0558 (12)0.0596 (13)0.0618 (13)0.0065 (10)−0.0066 (11)−0.0011 (10)
C1A0.055 (2)0.059 (2)0.0442 (18)0.0101 (16)0.0194 (16)0.0078 (15)
C2A0.0409 (16)0.0434 (16)0.0435 (16)0.0030 (13)0.0157 (13)0.0015 (13)
C3A0.0446 (17)0.0492 (18)0.0479 (18)−0.0023 (14)0.0129 (14)−0.0027 (14)
C4A0.0491 (17)0.0413 (16)0.0515 (17)0.0026 (13)0.0132 (15)−0.0009 (13)
C5A0.0420 (17)0.0535 (19)0.0498 (17)0.0078 (14)0.0095 (14)0.0018 (14)
C6A0.0468 (18)0.0459 (17)0.0530 (18)−0.0022 (13)0.0120 (15)−0.0059 (13)
C7A0.0444 (17)0.0441 (17)0.0520 (17)0.0035 (13)0.0215 (14)0.0037 (14)
C8A0.064 (2)0.0491 (18)0.0544 (18)0.0077 (14)0.0233 (16)0.0054 (14)
C9A0.069 (2)0.0492 (19)0.071 (2)−0.0037 (15)0.0088 (17)−0.0008 (15)
C10A0.068 (2)0.078 (2)0.069 (2)0.0022 (18)−0.0115 (18)−0.0118 (18)
O1B0.0522 (13)0.0547 (13)0.0659 (13)−0.0078 (10)0.0111 (10)−0.0179 (10)
O2B0.0443 (12)0.0910 (16)0.0590 (13)−0.0001 (12)−0.0020 (10)−0.0168 (11)
O3B0.0514 (12)0.0544 (13)0.0538 (12)0.0078 (10)0.0018 (9)0.0017 (10)
O4B0.0504 (12)0.0478 (11)0.0521 (12)0.0024 (9)−0.0089 (10)−0.0010 (9)
C1B0.0381 (18)0.067 (2)0.0520 (19)−0.0063 (15)0.0115 (15)−0.0141 (15)
C2B0.0382 (16)0.0581 (18)0.0409 (16)−0.0021 (14)0.0117 (13)−0.0038 (14)
C3B0.0381 (16)0.0455 (17)0.0410 (16)0.0036 (13)0.0098 (13)0.0033 (13)
C4B0.0428 (16)0.0402 (16)0.0474 (16)−0.0020 (13)0.0080 (14)0.0000 (13)
C5B0.0386 (16)0.0485 (18)0.0387 (15)−0.0018 (13)0.0090 (13)−0.0029 (13)
C6B0.0381 (16)0.0438 (16)0.0437 (16)0.0047 (12)0.0107 (13)0.0030 (12)
C7B0.0417 (16)0.0397 (16)0.0431 (15)0.0003 (13)0.0175 (13)−0.0005 (13)
C8B0.0486 (18)0.0493 (18)0.0581 (18)−0.0027 (14)0.0118 (14)−0.0050 (14)
C9B0.064 (2)0.050 (2)0.068 (2)0.0100 (15)0.0074 (16)0.0063 (15)
C10B0.0473 (19)0.062 (2)0.0578 (19)0.0068 (15)−0.0056 (15)−0.0028 (15)
Geometric parameters (Å, °) top
O1A—C1A1.373 (3)O1B—C1B1.376 (3)
O1A—C8A1.437 (3)O1B—C8B1.434 (3)
O2A—C1A1.200 (3)O2B—C1B1.202 (3)
O3A—C3A1.346 (3)O3B—C3B1.357 (3)
O3A—C9A1.440 (3)O3B—C9B1.422 (3)
O4A—C5A1.355 (3)O4B—C5B1.354 (3)
O4A—C10A1.428 (3)O4B—C10B1.434 (3)
C1A—C2A1.458 (4)C1B—C2B1.463 (4)
C2A—C7A1.377 (3)C2B—C7B1.372 (3)
C2A—C3A1.410 (4)C2B—C3B1.400 (4)
C3A—C4A1.376 (3)C3B—C4B1.368 (3)
C4A—C5A1.408 (4)C4B—C5B1.393 (3)
C4A—H4A0.9300C4B—H4B0.9300
C5A—C6A1.371 (4)C5B—C6B1.392 (4)
C6A—C7A1.374 (3)C6B—C7B1.373 (3)
C6A—H6A0.9300C6B—H6B0.9300
C7A—C8A1.495 (3)C7B—C8B1.497 (3)
C8A—H8A10.9700C8B—H8B10.9700
C8A—H8A20.9700C8B—H8B20.9700
C9A—H9A10.9599C9B—H9B10.9599
C9A—H9A20.9599C9B—H9B20.9599
C9A—H9A30.9599C9B—H9B30.9599
C10A—H10A0.9599C10B—H10D0.9599
C10A—H10B0.9599C10B—H10E0.9599
C10A—H10C0.9599C10B—H10F0.9599
C1A—O1A—C8A110.8 (2)C1B—O1B—C8B110.8 (2)
C3A—O3A—C9A116.7 (2)C3B—O3B—C9B117.3 (2)
C5A—O4A—C10A117.5 (2)C5B—O4B—C10B117.7 (2)
O2A—C1A—O1A120.2 (3)O2B—C1B—O1B120.0 (3)
O2A—C1A—C2A132.1 (3)O2B—C1B—C2B132.7 (3)
O1A—C1A—C2A107.7 (2)O1B—C1B—C2B107.3 (2)
C7A—C2A—C3A119.4 (2)C7B—C2B—C3B120.2 (2)
C7A—C2A—C1A108.8 (2)C7B—C2B—C1B109.1 (3)
C3A—C2A—C1A131.8 (3)C3B—C2B—C1B130.6 (3)
O3A—C3A—C4A125.1 (3)O3B—C3B—C4B124.3 (2)
O3A—C3A—C2A116.7 (2)O3B—C3B—C2B118.0 (2)
C4A—C3A—C2A118.2 (2)C4B—C3B—C2B117.7 (2)
C3A—C4A—C5A120.4 (3)C3B—C4B—C5B121.3 (2)
C3A—C4A—H4A119.8C3B—C4B—H4B119.4
C5A—C4A—H4A119.8C5B—C4B—H4B119.4
O4A—C5A—C6A124.8 (3)O4B—C5B—C6B123.7 (2)
O4A—C5A—C4A113.5 (2)O4B—C5B—C4B114.9 (2)
C6A—C5A—C4A121.6 (3)C6B—C5B—C4B121.3 (2)
C5A—C6A—C7A117.1 (2)C7B—C6B—C5B116.4 (2)
C5A—C6A—H6A121.5C7B—C6B—H6B121.8
C7A—C6A—H6A121.5C5B—C6B—H6B121.8
C6A—C7A—C2A123.3 (2)C2B—C7B—C6B123.1 (2)
C6A—C7A—C8A128.5 (3)C2B—C7B—C8B107.9 (2)
C2A—C7A—C8A108.2 (2)C6B—C7B—C8B129.0 (2)
O1A—C8A—C7A104.5 (2)O1B—C8B—C7B104.8 (2)
O1A—C8A—H8A1110.9O1B—C8B—H8B1110.8
C7A—C8A—H8A1110.9C7B—C8B—H8B1110.8
O1A—C8A—H8A2110.9O1B—C8B—H8B2110.8
C7A—C8A—H8A2110.9C7B—C8B—H8B2110.8
H8A1—C8A—H8A2108.9H8B1—C8B—H8B2108.9
O3A—C9A—H9A1109.5O3B—C9B—H9B1109.5
O3A—C9A—H9A2109.5O3B—C9B—H9B2109.5
H9A1—C9A—H9A2109.5H9B1—C9B—H9B2109.5
O3A—C9A—H9A3109.5O3B—C9B—H9B3109.5
H9A1—C9A—H9A3109.5H9B1—C9B—H9B3109.5
H9A2—C9A—H9A3109.5H9B2—C9B—H9B3109.5
O4A—C10A—H10A109.5O4B—C10B—H10D109.5
O4A—C10A—H10B109.5O4B—C10B—H10E109.5
H10A—C10A—H10B109.5H10D—C10B—H10E109.5
O4A—C10A—H10C109.5O4B—C10B—H10F109.5
H10A—C10A—H10C109.5H10D—C10B—H10F109.5
H10B—C10A—H10C109.5H10E—C10B—H10F109.5
C8A—O1A—C1A—O2A−179.8 (2)C8B—O1B—C1B—O2B179.5 (2)
C8A—O1A—C1A—C2A−0.5 (3)C8B—O1B—C1B—C2B−1.5 (3)
O2A—C1A—C2A—C7A178.2 (3)O2B—C1B—C2B—C7B178.6 (3)
O1A—C1A—C2A—C7A−1.0 (3)O1B—C1B—C2B—C7B−0.3 (3)
O2A—C1A—C2A—C3A−0.6 (5)O2B—C1B—C2B—C3B0.5 (5)
O1A—C1A—C2A—C3A−179.8 (3)O1B—C1B—C2B—C3B−178.5 (2)
C9A—O3A—C3A—C4A6.2 (4)C9B—O3B—C3B—C4B−3.4 (4)
C9A—O3A—C3A—C2A−172.6 (2)C9B—O3B—C3B—C2B177.8 (2)
C7A—C2A—C3A—O3A177.0 (2)C7B—C2B—C3B—O3B180.0 (2)
C1A—C2A—C3A—O3A−4.3 (4)C1B—C2B—C3B—O3B−2.0 (4)
C7A—C2A—C3A—C4A−1.9 (4)C7B—C2B—C3B—C4B1.1 (4)
C1A—C2A—C3A—C4A176.8 (3)C1B—C2B—C3B—C4B179.1 (2)
O3A—C3A—C4A—C5A−178.2 (2)O3B—C3B—C4B—C5B−179.5 (2)
C2A—C3A—C4A—C5A0.6 (4)C2B—C3B—C4B—C5B−0.7 (4)
C10A—O4A—C5A—C6A0.5 (4)C10B—O4B—C5B—C6B0.2 (4)
C10A—O4A—C5A—C4A−179.9 (2)C10B—O4B—C5B—C4B179.1 (2)
C3A—C4A—C5A—O4A−178.9 (2)C3B—C4B—C5B—O4B−179.2 (2)
C3A—C4A—C5A—C6A0.7 (4)C3B—C4B—C5B—C6B−0.2 (4)
O4A—C5A—C6A—C7A179.0 (2)O4B—C5B—C6B—C7B179.6 (2)
C4A—C5A—C6A—C7A−0.6 (4)C4B—C5B—C6B—C7B0.8 (4)
C5A—C6A—C7A—C2A−0.8 (4)C3B—C2B—C7B—C6B−0.6 (4)
C5A—C6A—C7A—C8A−179.5 (3)C1B—C2B—C7B—C6B−179.0 (2)
C3A—C2A—C7A—C6A2.1 (4)C3B—C2B—C7B—C8B−179.8 (2)
C1A—C2A—C7A—C6A−176.9 (2)C1B—C2B—C7B—C8B1.8 (3)
C3A—C2A—C7A—C8A−178.9 (2)C5B—C6B—C7B—C2B−0.4 (4)
C1A—C2A—C7A—C8A2.1 (3)C5B—C6B—C7B—C8B178.7 (2)
C1A—O1A—C8A—C7A1.7 (3)C1B—O1B—C8B—C7B2.5 (3)
C6A—C7A—C8A—O1A176.6 (2)C2B—C7B—C8B—O1B−2.6 (3)
C2A—C7A—C8A—O1A−2.3 (3)C6B—C7B—C8B—O1B178.2 (2)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C6A—H6A···O1Bi0.932.513.397 (3)161
C8A—H8A1···O2Bii0.972.533.337 (3)140
C6B—H6B···O1Aiii0.932.443.325 (3)159
Symmetry codes: (i) x+1, y, z; (ii) −x, −y+1, −z+1; (iii) x, y, z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C6A—H6A···O1Bi0.932.513.397 (3)161
C8A—H8A1···O2Bii0.972.533.337 (3)140
C6B—H6B···O1Aiii0.932.443.325 (3)159
Symmetry codes: (i) x+1, y, z; (ii) −x, −y+1, −z+1; (iii) x, y, z+1.
Acknowledgements top

The authors acknowledge financial support from the National Natural Science Foundation of China (20872179) and the Science and Technology Commission of Shanghai Municipality (STCSM) (08DZ1971504).

references
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