Crystal structure of N-isopropyl-N-(phenyl)phenylglyoxylamide

The title compound, C17H17NO2, was synthesized and its photoreactive properties in the crystalline state were investigated. A solid-state photoreaction did not occur because the reaction sites were too far apart in the molecule.


Chemical context
An achiral molecule of N,N-diisopropylarylglyoxylamide 1a having two isopropyl groups crystallizes in the chiral space group P2 1 2 1 2 1 and is transformed to the optically active -lactam derivative 2a upon UV light irradiation ( Fig. 1; Toda et al., 1987Toda et al., , 1993Sekine et al., 1989;Hashizume et al., 1995Hashizume et al., , 1996Hashizume et al., , 1998. Likewise, N-ethyl-N-isopropylphenylglyoxylamide 1b, having an ethyl group and an isopropyl group, forms a chiral crystal (P2 1 2 1 2 1 ), and its photoirradiation in the solid state yields the optically active -lactam derivative 2b ( Fig. 1; Toda et al., 1997). Therefore, we synthesized the title compound 1c having a phenyl group and an isopropyl group, and investigated whether an optically active -lactam derivative could be obtained by photoreaction of its crystals. It was found that the photoreaction did not proceed in the solid state. In this paper, an explanation for the lack of photoreactivity is presented based on single crystal X-ray structural analysis.
In order for the Norrish-Yang reaction to take place, the reacting atoms in the molecular structure must be in close proximity. In the crystal structure of 1c, the distance between the -hydrogen atom H15 and the carbonyl oxygen atom O1 is 4.565 Å . This interatomic distance is much longer than the ideal value of up to about 2.7 Å , at which photoreaction can proceed in the crystal (Konieczny et al., 2018). Moreover, the distance between the reacting C7 and C15 carbon atoms is 3.845 (2) Å , which is outside the range of ideal values of up to about 3.2 Å . These interatomic distances in 1c are large enough to prevent the photoreaction from taking place. In contrast, the corresponding distances are 2.78 (4) and 2.871 (4) Å in 1a, and 2.81 (3) and 2.897 (3) Å in 1b. As those distances are close to the ideal values, the photoreaction could occur in the crystalline state.

Supramolecular features
In the crystal of 1c, the molecules are linked by weak intermolecular C-HÁ Á ÁO interactions (C10-H10Á Á ÁO1 i and C13-H13Á Á ÁO2 ii ; symmetry codes as in Table 1), forming a layer structure parallel to the ab plane (Fig. 3).

D-HÁ
(0.72 ml, 5 mmol) and triethylamine (0.70 ml, 5 mmol) in dry diethyl ether (2 ml) was added a solution of benzoylformyl chloride (0.84 g, 5 mmol) in dry diethyl ether (2 ml), and the reaction mixture was stirred for 3 h in an ice bath. After filtration of triethylammonium chloride, the filtrate was washed with dilute HCl and aqueous NaHCO 3 and dried over MgSO 4 . The crude product was recrystallized from benzene to give 1c as colourless prisms (0.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were positioned in geometrically calculated positions (C-H = 0.95-0.98 Å ) and refined using a riding model with U iso (H) = 1.2U eq (C) and 1.5U eq (C-methyl).

Funding information
A part of this work was supported by JSPS KAKENHI Grant Nos. JP17K05745 and JP18H04504.

2-Oxo-N,2-diphenyl-N-(propan-2-yl)acetamide
Crystal data Special details 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.