Diethyl [hydroxy(2-nitrophenyl)methyl]phosphonate

In the title molecule, C11H16NO6P, the nitro group is twisted out of the mean plane of the benzene ring at 29.91 (3)°. The two ethyl groups are disordered between two orientations in the ratios 0.784 (7)/0.216 (7) and 0.733 (6)/0.267 (6). Intermolecular O—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers.

In the title molecule, C 11 H 16 NO 6 P, the nitro group is twisted out of the mean plane of the benzene ring at 29.91 (3) . The two ethyl groups are disordered between two orientations in the ratios 0.784 (7)/0.216 (7) and 0.733 (6)/0.267 (6). Intermolecular O-HÁ Á ÁO hydrogen bonds link the molecules into centrosymmetric dimers.

Comment
Phosphonates, especially enantiomerically pure forms, are particularly important in connection with their remarkable biological activities. They have been used as enzyme inhibitors, antibacterial agents, anti-HIV agents, botryticides, and haptens for catalytic antibodies (Allen et al., 1978;Hirschmann et al., 1994). In this regard, the preparation of various optically active phosphonates with a diversity of structures is highly desirable for drug discovery and medicinal chemistry. The title compound (I) was obtained in the reaction of diphenylphosphite with an aromatic aldehyde in the presence of triethylamine.
After 15 minutes, triethylamine (0.1 ml) was added, and the reaction mixture was stirred for 2 h at 0°C. The resulting solution was washed with saturated NaHCO 3 solution, extracted with dichloromethane and dried over MgSO 4 . The solution was filtered and purified by column chroatography on silica gel, using ehtyl acetate and petroleum as eluant to afford the title compound. Crystals of (I) suitable for X-ray data collection were obtained by slow evaporation of a chloroform and methanol solution in ratio of 100:1 at 293 K.

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^ > 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.