2-(2,5-Dimethoxyphenyl)-N-[2-(4-hydroxyphenyl)ethyl]acetamide

In the title compound, C18H21NO4, the dihedral angles between the acetamide group and the methoxy- and hydroxy-substitured benzene rings are 80.81 (5) and 8.19 (12)°, respectively. The benzene rings are twisted with respect to each other, making a dihedral angle of 72.89 (5)°. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

In the title compound, C 18 H 21 NO 4 , the dihedral angles between the acetamide group and the methoxy-and hydroxy-substitured benzene rings are 80.81 (5) and 8.19 (12) , respectively. The benzene rings are twisted with respect to each other, making a dihedral angle of 72.89 (5) . In the crystal, N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional network.

Data collection
Bruker SMART CCD area-detector diffractometer 8417 measured reflections 3638 independent reflections 2352 reflections with I > 2(I) R int = 0.063 Refinement R[F 2 > 2(F 2 )] = 0.040 wR(F 2 ) = 0.088 S = 0.87 3638 reflections 216 parameters H atoms treated by a mixture of independent and constrained refinement Á max = 0.11 e Å À3 Á min = À0.12 e Å À3 Table 1 Hydrogen-bond geometry (Å , ). (2) 3.023 (2)  We wish to thank the DBIO company for partial support of this work.  (Kubo et al., 2000), and its inhibition is one of the major strategies in developing new whitening agents. Over the last few decades, various tyrosinase inhibitors, including azelaic acid (Lemic-Stojcevic et al., 1995), kojic acid (Battaini et al., 2000), arbutin (Cabanes et al., 1994), and N-phenylthiourea (PTU) (Thanigaimalai et al., 2010) have been studied. But some of their individual activities are either not potent enough to be considered of practical use or not compatible with safety regulations for food and cosmetic additives. In our continuing search for tyrosinase inhibitors, we have synthesized the title compound, (I), from the reaction of 2,5-dimethoxyphenyl acetyl chloride and tyramine under ambient conditions. Herein, the crystal structure of (I) is described (Fig. 1).

Experimental
The starting materials, 2,5-dimethoxyphenyl acetyl chloride and tyramine, were purchased from Sigma Chemical Co.
Solvents for organic synthesis were redistilled before use. All other chemicals and solvents were of analytical grade and were used without further purification. The title compound was prepared from the reaction of 2,5-dimethoxyphenyl acetyl chloride (0.21 g, 1.0 mmol) and tyramine (0.14 g, 1.0 mmol) by simple substitution in THF (6 ml) triethylamine (0.12 g, 1.2 mmol). The solvent was removed under reduced pressure. The mixture was purified by column chromatography on silica gel (2:1 dichloromethane/ethylacetate) to give the title compound. Colourless crystals were obtained by slow evaporation of its ethanol solution at room temperature.

Refinement
H atoms of the NH and OH groups were located in a difference Fourier map and refined freely (N-H = 0.88 (2) Å and O -H = 0.87 (3) Å]. Other H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93-0.97 Å, and with U iso (H) = 1.2U eq (C) for aromatic and methylene, and 1.5U eq (C) for methyl H atoms. In the absence of significant anomalous scattering effects, 1471 Friedel pairs were averaged in the final refinement.    where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.11 e Å −3 Δρ min = −0.12 e Å −3

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.