1-(2-Hydroxy-4,5-dimethoxyphenyl)ethanone

The molecular structure of the title compound, C10H12O4, contains an intramolecular hydrogen bond between the phenol and acetyl substituents. In the crystal, C—H⋯π interactions act between the molecules in a cyclic manner to stabilize stacks of molecules along the b axis. Several C—H⋯O interactions are present between the stacks.

The molecular structure of the title compound, C 10 H 12 O 4 , contains an intramolecular hydrogen bond between the phenol and acetyl substituents. In the crystal, C-HÁ Á Á interactions act between the molecules in a cyclic manner to stabilize stacks of molecules along the b axis. Several C-HÁ Á ÁO interactions are present between the stacks.

Related literature
For a review on lamellarin alkaloids, see: Fan et al. (2008). The experimental procedure of Combes et al. (2002) for a related Fries rearrangement was adapted for the synthesis of the title compound. For alternative syntheses of the title compound by Fries rearrangement, see: Ploypradith et al. (2003); Nolan et al.  Table 1 Hydrogen-bond geometry (Å , ).
The compound crystallizes in the polar space group Pca2 1 . An intramolecular hydrogen bond exists between the phenol and acetyl groups (Fig. 1). Molecules related by translation along the b axis interact through two C-H···π interactions which act between the molecules in a cyclic manner. These stabilize stacks of molecules along the b axis ( Fig. 2). Several C-H···O interactions exist in the structure, the most significant being listed in Table 1. These act between the stacks to stabilize the structure (Fig. 3).

Experimental
The experimental procedure of Combes et al.. (2002) for a related Fries rearrangement was adapted for the synthesis of the title compound. Boron trifloride etherate (20 ml, 23.1 g, 163 mmol) was cautiously added to ice-cooled 3,4-dimethoxyphenyl acetate (7.99 g, 40.7 mmol). The mixture was warmed to room temperature, then heated to 383 K for 5 h before being cooled again to room temperature and stirred for an additional 18 h. Water (50 ml) was added, resulting in the precipitation of a brown solid. This was filtered off, washed with a copious amount of water, then recrystallized from methanol to afford 1-(2-hydroxy-4,5-dimethoxyphenyl)ethanone (4.90 g, 61%) as dark yellow blocks, m.p. 385-386 K.

Refinement
All H atoms attached to carbon were positioned geometrically, and allowed to ride on their parent atoms, with C-H bond lengths of 0.95 Å (CH) or 0.98 Å (CH 3 ), and isotropic displacement parameters set to 1.2 (CH) or 1.5 times (CH 3 ) the U eq of the parent atom. Friedel pairs were merged during final refinement.

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.