5,7-Dimethoxy­isobenzofuran-1(3H)-one

Ming-Xue Sun; Xu Li; Wen-Yong Liu; Kai Xiao

doi:10.1107/S1600536809031183

. 2009 Aug 15;65(Pt 9):o2146. doi: 10.1107/S1600536809031183

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

Ming-Xue Sun ^a, Xu Li ^b, Wen-Yong Liu ^a, Kai Xiao ^a,^*

PMCID: PMC2969903 PMID: 21577555

Abstract

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].

Related literature

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, see: Zuo et al. (2008 ▶); Lee et al. (2001 ▶). For the title compound as a byproduct, see: Fürstner et al. (2000 ▶).

Experimental

Crystal data

C₁₀H₁₀O₄
M _r = 194.18
Monoclinic,
a = 8.532 (3) Å
b = 25.877 (10) Å
c = 8.374 (3) Å
β = 104.322 (6)°
V = 1791.5 (11) Å³
Z = 8
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 293 K
0.12 × 0.12 × 0.10 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.987, T _max = 0.989
7489 measured reflections
3216 independent reflections
1766 reflections with I > 2σ(I)
R _int = 0.062

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.131
S = 0.93
3216 reflections
258 parameters
H-atom parameters constrained
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.19 e Å⁻³

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

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809031183/wm2246sup1.cif

e-65-o2146-sup1.cif^{(21.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809031183/wm2246Isup2.hkl

e-65-o2146-Isup2.hkl^{(157.8KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6A—H6A⋯O1Bⁱ	0.93	2.51	3.397 (3)	161
C8A—H8A1⋯O2Bⁱⁱ	0.97	2.53	3.337 (3)	140
C6B—H6B⋯O1Aⁱⁱⁱ	0.93	2.44	3.325 (3)	159

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

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).

supplementary crystallographic information

Comment

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 ).

Experimental

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.