Crystal structure of 1-(4-methoxyphenyl)-4-(4-nitrophenyl)-3-phenoxyazetidin-2-one

In the title compound, C22H18N2O5, the central β-lactam ring (r.m.s. deviation = 0.002 Å) makes dihedral angles of 64.21 (14), 82.35 (12) and 20.66 (13)° with the phenyl ring and the nitro- and methoxybenzene rings, respectively. The molecular structure is stabilized by an intramolecular C—H⋯O hydrogen bond. In the crystal, molecules are linked via C—H⋯O hydrogen bonds, forming slabs lying parallel to (111). The slabs are linked via C—H⋯π interactions, forming a three-dimensional network.

In the title compound ( Fig. 1) A weak intramolecular C-H···O hydrogen bond stabilizes the molecular conformation (Table 1).
In the crystal, molecules are linked by C-H···O hydrogen bonds forming slabs lying parallel to (111). The slabs are linked via C-H···π interactions forming a three dimensional network (Table 1 and Fig. 2).

S3. Refinement
All H atoms were placed in calculated positions, with C-H = 0.93 -0.98 Å, and refined using a riding model with U iso (H) = 1.5U eq (C) for methyl H atoms and = 1.2U eq (C) for other H atoms. The crystal was of very low quality and in the final cycles of refinement 45 reflections were omitted owing to very bad agreement [reflections (-6 7 5), (-6 7 3), (-5 8

Figure 1
Perspective view of the molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
View of the hydrogen bonding and molecular packing of the title compound along a axis (only H atoms involved in hydrogen bonding are shown; see Table 1 for details).  Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.19496 (17