Crystal structure of 4-(naphthalen-2-yl)-2-oxo-6-phenyl-1,2-dihydropyridine-3-carbonitrile

The structure of 4-(naphthalen-2-yl)-2-oxo-6-phenyl-1,2-dihydropyridine-3-carbonitrile, prepared by a three-component one-pot reaction, is based on dimers connected by N—H⋯O hydrogen bonds, which also interact through π–π contacts.


Chemical context
Pyridine skeletons play a pivotal role in drug discovery with more than 7000 existing drugs containing this moiety (De et al., 2022).Recent investigations of 3-cyanopyrid-2-one derivatives have shown that the unsaturated and cyanide moieties significantly increase their biological activities compared to the original pyridine skeleton.The practical value of these compounds and the broad spectrum of biological activities (ranging from antitumor, anti-tuberculosis, anti-inflammatory, antimicrobial activities to anti-SARS-CoV-2) have made the 3-cyanopyrid-2-ones become the subject of intensive research in pyridine chemistry (Saleh et al., 2021).Beside their promising biological activity, the 3-cyanopyrid-2-ones are also used in materials chemistry involving production of OLED devices, dyes, pigments, and other important applications.
Based on a substituted pyridone scaffold, Cheney et al. (2007) identified a novel series of Pim-1 kinase inhibitors that could compete and interfere with Pim-1 ATP utilization (Cheney et al., 2007).
By performing a high throughput screening and an NMRbased fragment screen, 3-cyanopyridones have been discovered and structurally optimized by hit-to-lead processes to become a novel inhibitor of M. tuberculosis thymidylate kinase (Mtb TMK) showing cellular activity against M. tuberculosis (Naik et al., 2015).
Recently, based on the cyclization reaction between 2-nitro-1,3-dicarbonylic compounds and cyanoacetamide, 2-pyridone rings have been synthesized.These compounds are able to inhibit the aggregation of �-synuclein in human cultured cells and prevent the degeneration of dopaminergic neurons in the search for novel molecules for the treatment of Parkinson's disease (Mahı ´a et al., 2021).The syntheses of 3-cyanopyrid-2ones are well documented and highlighted in the review of Litvinov (2006).These compounds can be synthesized by modification of a substituent in a preformed pyridine substrate or by formation of a C-N bond by a cyclization reaction.During our study on the use of elemental sulfur (Nguyen, 2017a(Nguyen, ,b, 2020) ) as a versatile sulfurating and oxidizing agent for the syntheses of heterocyclic compounds such as thiophene, furan, benzothiazine, we noticed that the product of the Michael addition of cyanoacetamide on chalcone can undergo the formation of a C-N bond and aromatization to form the desired 3-cyanopyrid-2-ones in good yield.

Structural commentary
The title compound crystallizes in the solvent-free form in the centrosymmetric monoclinic space group P2 1 /n with one molecule in the asymmetric unit.The molecular structure is shown in Fig. 1.The �-lactam moiety is almost planar with a maximum deviation from planarity for the N atom of the cyanide group (N31) of 0.047 (2) A ˚.The phenyl group and the lactam moiety form a dihedral angle of 50.4 (4) � while the naphthyl group is rotated by 35.6 (5) � with respect to the central lactam ring.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Positional parameters for the H atom attached to the N atom were refined.All H atoms bonded to C atoms were placed at calculated positions, with C-H = 0.93 A ˚, and refined as riding with U iso (H) = 1.2U eq (C) for Csp 2 -H.SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: Olex2 1.5 (Dolomanov et al., 2009); software used to prepare material for publication: Olex2 1.5 (Dolomanov et al., 2009).

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.

Table 2
Experimental details.