Methyl 2-{[(4-hydroxyphenyl)(methoxycarbonyl)methyl]aminocarbonyl}ethanoate hemihydrate

In the structure of the title compound, C13H15NO6·0.5H2O, the water O atom lies on a twofold rotation axis. The methoxycarbonylmethyl and amino groups are essentially coplanar and the methoxycarbonylmethyl group makes a dihedral angle of 79.73 (10)° with the mean plane of the hydroxyphenyl ring. The amino and methoxycarbonylmethyl groups are involved in an intramolecular N—H⋯O hydrogen bond which generates an S(5) ring motif. In the crystal structure, molecules are linked via N—H⋯O and O—H⋯O hydrogen bonds and weak C—H⋯O interactions into a two-dimensional network parallel to the (01) plane. The crystal structure is further stabilized by C—H⋯π interactions.

We have synthesized the title compound and its structure is reported here.
The asymmetric unit of the title compound contains one molecule of C 13 H 15 NO 6 and half an H 2 O molecule with the O1W atom lying on a twofold rotation axis, (Fig. 1). The methoxycarbonylmethyl [C4/C5/C7/O3/O5] and the C3/N1/C4 amino sections of the molecule are essentially coplanar with a dihedral angle of 3.12 (10)° between them. An intramolecular N1-H1N1···O3 hydrogen bond ( Fig. 1) generates an S(5) ring motif (Bernstein et al., 1995) and contributes to this planarity.
In the crystal packing ( Table 1). The crystal is further stablized by C-H···π interactions (Table 1); Cg 1 is the centroid of the C8-C13 phenyl ring.

Experimental
The title compound was synthesized via condensation between an equimolar amount of hydroxyphenylglycine methylester (10.0 g, 60 mmol) and methylmalonate potassium salt (9.4 g, 60 mmol) in acetonitrile/water (140:40 ml) at 273 K. The mixture was stirred for 2 h in the presence of dicyclohexylcarbodiimide, which acted as a catalyst and a peptide-coupling agent. The white precipitate formed during the reaction was filtered and washed thoroughly with dichloromethane. The filtrate and the dichloromethane were combined and evaporated. The resulting crude product was partitioned between water and dichloromethane, and the dichloromethane extract was dried over anhydrous magnesium sulfate and evaporated.
Colorless needle-shaped single crystals suitable for X-ray structure determination were obtained by slow evaporation of dichloromethane/petroleum ether (5:1 v/v) solution after several days (10.93 g, 65%).

Refinement
The amino, hydroxyl and water hydrogen atoms were located in a difference map and refined isotropically. Hydrogen atoms attached to the carbon atoms were constrained in a riding motion approximation with d(C-H) = 0.93 Å, U iso =1.2U eq (C) for aromatic, 0.98 Å, U iso = 1.2U eq (C) for CH, 0.97 Å, U iso = 1.2U eq (C) for CH 2 , 0.96 Å, U iso = 1.5U eq (C) for CH 3 atoms. A rotating group model was used for the methyl groups. In the absence of significant anomalous scattering effects, a total of 1388 Friedel pairs were merged before final refinement.

Special details
Experimental. The data was collected with the Oxford Cyrosystem Cobra low-temperature attachment. 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 > 2sigma(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.