3-(2-Methoxyphenyl)-2,3-dihydro-1H-benzo[f]chromen-1-one

In the title flavanone, the molecules are linked by weak C—H⋯O interactions into [101] chains.


Structure description
Flavanones are widely used as health-care products because they are found at high concentrations in natural sources (Lichota et al., 2019). Flavanones possess a chromane ring as a common structural feature, but they show a broad spectrum of biological activities depending on the placement of the hydroxyl or methoxy group substituents at different positions of the flavanone skeleton (Lee et al., 2016;Singh et al., 2014). Compounds in which the phenyl group in the chromane ring system is replaced by a naphthyl ring system have shown versatile biological activities and physiochemical properties (Kumar et al., 2017;Shin et al., 2014). Therefore, the naphthyl ring systemcontaining title flavanone compound, C 20 H 16 O 3 , was synthesized and its crystal structure was determined.
In the crystal, weak C-HÁ Á ÁO interactions link the molecules into C(7) chains propagating along [101] (Table 1, Fig. 2) with adjacent molecules in the chain related by n-glide symmetry.

Synthesis and crystallization
The synthetic scheme for the preparation of the title compound is shown in Fig. 3: 2-hydroxy-1-acetonaphthone (I, 372 mg, 2 mmol) and 2-methoxybenzaldehyde (II, 272 mg, 2 mmol) were dissolved in ethanol (20 ml) and the temperature was adjusted to around 276-277 K in an ice-bath. To the cooled reaction mixture was added 1.5 ml of 50% aqueous KOH solution, and the reaction mixture was stirred at room temperature for 24 h. The mixture was poured into iced water (80 ml) and was acidified with 6 N HCl solution. The mixture was extracted with ethyl acetate (3 Â 40 ml) and the combined organic layers were dried with MgSO 4 . Filtration and evaporation of the filtrate gave a solid product of chalcone (III), which was used for next reaction: the solid was dissolved in DMSO and a catalytic amount of conc. HCl was added. After stirring for 10 h, the reaction mixture was poured into iced water to give a solid product of the title flavanone and yellow blocks were recovered by recrystallization from ethanol solution.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Table 1 Hydrogen-bond geometry (Å , ).

Figure 2
Part of the crystal structure of the title compound, showing the weak C-HÁ Á ÁO hydrogen bonds as blue lines. H atoms not involved in these interactions have been omitted for clarity.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level.

data-1
IUCrData ( where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.32 e Å −3 Δρ min = −0.20 e Å −3 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.