Synthesis, structure and Hirshfeld surface analysis of 2-oxo-2H-chromen-4-yl pentanoate

In the title compound, the dihedral angle between the coumarin ring system and the pentanoate ring is 36.26 (8)°. A short intramolecular C—H⋯O contact is observed.


Chemical context
Coumarins are naturally occurring molecules with a versatile range of activities.Their structural and physicochemical characteristics make them a privileged scaffold in medicinal chemistry and chemical biology (Carneiro et al., 2021).Historically, coumarins have been applied for the treatment of a variety of diseases due to their anticoagulant, anti-inflammatory, antiviral, antimicrobial, anticancer, antioxidant (Todorov et al., 2023) and anti-glaucoma (Ziki et al., 2023) activities.Their wide range of biological activities and the use of coumarin-containing drugs clinically have contributed to the growing interest in this class of heterocycles (Khandy et al., 2024).Given their importance, coumarin derivatives continue to be our field of research (Kambo et al., 2017;Hollauer et al., 2023).We report herein the synthesis, crystal structure, and Hirshfeld surface analysis of the title coumarin derivative.

Structural commentary
The molecular structure of the title coumarin derivative is illustrated in Fig. 1.An S(6) ring motif arises from an intra-molecular C2-H2� � �O4 hydrogen bond (Table 1).As expected, the coumarin ring system is almost planar, with a maximum deviation from the plane of 0.016 (3) A ˚for atom C7.An inspection of the bond lengths shows that there is a slight asymmetry of the electronic distribution around the pyrone ring: the C1-C2 [1.336 (3) A ˚] and C2-C3 [1.437 (3) A ˚] bond lengths are shorter and longer, respectively, than those excepted for a C ar -C ar bond.This suggests that the electron density is preferentially located in the C1-C2 bond of the pyrone ring, as seen in other coumarin derivatives (Gomes et al., 2016;Oue ´draogo et al., 2018).

Supramolecular features and Hirshfeld surface analysis
In the crystal, C5-H5� � �O1 hydrogen bonds link molecules into infinite chains along the [001] direction (Table 1, Fig. 2) and the C11-H11B� � �O1 interactions contribute to the crystal cohesion.The intermolecular interactions were quantified using Hirshfeld surface analysis.This approach is a graphical tool for visualization and understanding of intermolecular interactions.The Hirshfeld surface analysis was performed, and the two-dimensional (2D) fingerprint plots were generated with CrystalExplorer 17 (Spackman et al., 2021).Fig. 3 shows the Hirshfeld surface plotted over d norm (normalized contact distance) and Fig. 4 the 2D fingerprint plots..

Figure 2
Part of crystalline packing of the title compound showing a parallel chain in the [001] direction.Dashed lines indicate hydrogen bonds.H atoms not involved in hydrogen-bonding interactions have been omitted for clarity.

Figure 3
The Hirshfeld surface mapped over d norm for visualizing the intermolecular contacts of the title compound.
4.7 molar equivalents) and 4-hydroxycoumarin (6.17 mmol, 1 g) in small portions over 30 min, with vigorous stirring.The reaction mixture was left stirring at room temperature for 3 h.The mixture was then poured in a separating funnel containing 40 ml of chloroform and washed with diluted hydrochloric acid solution until the pH was 2-3.The organic layer was extracted, washed with water to neutrality, dried over MgSO 4 and the solvent removed.The crude product was filtered off with suction, washed with n-hexane and recrystallized from acetone.Dirty white crystals of the title compound were obtained in a good yield (78%), m.p. 408-409 K.

Special details
Experimental.CrysAlisPro 1.171.42.102a (Rigaku Oxford Diffraction, 2023) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.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.

Figure 1
Figure 1Molecular structure of the compound showing the atomic numbering system.Displacement ellipsoids are drawn at the 50% probability level.

Figure 4 Fingerprint
Figure 4 Fingerprint plots for the title compound showing (a) C� � �C, (b) H� � �H, (c) O� � �H/H� � �O and (d) C� � �H/H� � �C interactions.The outline of the full fingerprint is shown in grey.d i is the closest internal distance from a given point on the Hirshfeld surface and d e is the closest external contact.

Table 2
Experimental details.