5-Methoxy-2-benzofuran-1(3H)-one

In the title compound, C9H8O3, the molecular skeleton is almost planar, with an r.m.s. deviation of 0.010 (2) Å. In the crystal, weak C—H⋯O hydrogen bonds connect the molecules into a two-dimensional network parallel to the ac plane.

In the title compound, C 9 H 8 O 3 , the molecular skeleton is almost planar, with an r.m.s. deviation of 0.010 (2) Å . In the crystal, weak C-HÁ Á ÁO hydrogen bonds connect the molecules into a two-dimensional network parallel to the ac plane.

Experimental
Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; 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: WinGX (Farrugia, 1999). Isobenzofuran-1(3H)-ones (phthalides) are a class of heterocyclic compounds which occur in several natural products and have been investigated for several biological properties, such as antiplatelet (Ma et al., 2012) and antioxidant activities (Huang et al., 2012), inhibition of glutamate induced cytotoxicity in PC12 cells (Zhao et al., 2012) and phytotoxicity (Arnone et al., 2002). The title compound, C 9 H 8 O 3 was obtained as an intermediate in a synthetic route in the preparation of compounds endowed with phytotoxic activity and we report the crystal structure of it in a continuation of our work on the synthesis of phthalides (Pereira et al., 2012).
The title molecule ( Fig. 1) is essentially planar with a mean deviation of 0.010 (2) Å from the least squares plane traced by 12 non-H atoms. All bond distances and angles agree well with those reported in the related compounds (Sun et al., 2009;Mendenhall et al., 2003;Pereira et al., 2012). In the crystal, molecules are linked via weak C6-H6···O1 hydrogen bonds (Table 1) forming chains along the ac plane. These layers are extended by C8-H8A···O2 hydrogen bonds into a two-dimensional network structure (Fig. 2).

Experimental
Starting materials were commercially available from Sigma Aldrich (USA) and were used without further purification. 5-Methoxyisobenzofuran-1(3H)-one was prepared as follows (Zhang et al., 2009). A tube of 40 ml equipped with a magnetic stir bar was charged with palladium(II) acetate (67.3 mg, 0.30 mmol), potassium bicarbonate (750 mg, 7.50 mmol), 4-methoxybenzoic acid (456 mg, 3.00 mmol) and dibromomethane (12 ml). The tube was sealed with a teflon cap and the reaction mixture was stirred at 140 °C for 18 h. After this time, the mixture was filtered through a pad of celite.

Figure 1
The molecular structure of the title compound, showing the atom labeling and displacement ellipsoids are drawn at the 30% probability level.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.16 e Å −3 Δρ min = −0.13 e Å −3 Special details 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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.