3-Isobutyl-5,5-diphenylimidazolidine-2,4-dione

The imidazolidine ring is slightly ‘ruffled’ and the isobutyl substituent is rotated well out of the plane of its ring. In the crystal, inversion dimers are formed by pairs of N—H⋯O hydrogen bonds with C—H⋯O hydrogen bonds linking them into chains parallel to (10 ). The chains are joined into layers parallel to the ac plane by C—H⋯π(ring) interactions.


Structure description
Imidazolidin-2,4-dione, also known as hydantoin, is an important nucleus found in numerous natural products and in several clinically important medicines. One of the best known examples of such a derivative is phenytoine, 5,5-diphenylimidazolidine-2,4-dione, a drug widely prescribed as an anticonvulsant agent and for the treatment of many other diseases including HIV (Weichet, 1974;Havera & Strycker, 1976;Khodair et al., 1997;Thenmozhiyal et al., 2004).
Given the wide range of therapeutic applications for such compounds, and in a continuation of our work in this area (Ramli et al., 2017a,b;Akrad et al. 2017;Guerrab et al. 2019Guerrab et al. , 2020aGuerrab et al. ,b, 2021Guerrab et al. , 2022, the title compound ( Fig. 1) was prepared and its crystal structure is reported here.
The two phenyl rings (C4-C9 and C10-C15) are disposed on either side of the fivemembered ring and make dihedral angles of 68.42 (3) and 73.04 (3) , respectively, with the mean plane of the latter ring. The five-membered ring is slightly 'ruffled' with deviations from the mean plane ranging from 0.206 (5) Å (N2) to À0.218 (5) Å (C3) (r.m.s. deviation = 0.0155 Å ). The isobutyl group is rotated well out of the mean plane of the five-membered ring, as indicated by the C2-N1-C16-C17 torsion angle of 72.64 (10) . In the crystal, inversion dimers are formed by pairs of N2-H2Á Á ÁO2 hydrogen bonds (Table 1) with the dimers connected by C8-H8Á Á ÁO1 hydrogen bonds, forming chains of molecules extending parallel to (101) (Fig. 2 and Table 2). The chains data reports are connected into layers parallel to the ac plane by C7-H7Á Á ÁCg1 interactions (Table 1 and Fig. 3).

Synthesis and crystallization
To a solution of 5,5-diphenylimidazolidine-2,4-dione (500 mg, 1.98 mmol), one equivalent of isobutyl bromide (246.88 mL, 1.98 mmol) in absolute dimethylformamide (DMF, 15 ml) was added and the resulting solution heated under reflux for 3 h in the presence of 1.1 equivalents of K 2 CO 3 (301.31 mg, 2.18 mmol). The reaction mixture was filtered while hot, and the solvent evaporated under reduced pressure. The residue obtained was dried and recrystallized from an ethanol solution to yield colourless prism-like crystals (Guerrab et al., 2018) Refinement Crystal data, data collection and structure refinement details are presented in Table 2. A small amount of residual density, well removed from the main molecule and which could not be satisfactorily modelled by a plausible solvent molecule disordered across a centre of symmetry was removed with PLATON SQUEEZE (Spek, 2015). Three reflections affected by the beamstop were omitted from the final refinement.

Figure 2
A portion of one layer viewed along the b-axis direction with N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds depicted, respectively, by violet and black dashed lines. C-HÁ Á Á(ring) interactions are depicted by green dashed lines and non-interacting hydrogen atoms are omitted for clarity.

Figure 3
Packing viewed along the c-axis direction with intermolecular interactions depicted as in Fig. 2 and non-interacting hydrogen atoms omitted for clarity. Table 1 Hydrogen-bond geometry (Å , ).
Cg1 is the centroid of the five-membered ring.

Figure 1
The title molecule with the labelling scheme and 50% probability ellipsoids.  Special details Experimental. The diffraction data were obtained from 9 sets of frames, each of width 0.5° in ω or φ, collected with scan parameters determined by the "strategy" routine in APEX3. The scan time was 5 sec/frame. Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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. H-atoms attached to carbon were placed in calculated positions (C-H = 0.95 -1.00 Å) and were included as riding contributions with isotropic displacement parameters 1.2 -1.5 times those of the attached atoms. That attached to nitrogen was placed in a location derived from a difference map and refined with a DFIX 0.91 0.01 instruction. A small amount of residual density, well-removed from the main molecule and which could not be satisfactorily modeled by a plausible solvent molecule disordered across a center of symmetry was removed with PLATON SQUEEZE (Spek, 2015). Three reflections affected by the beamstop were omitted from the final refinement.