(E)-2-(3,5-Dimethoxybenzylidene)indan-1-one

The title compound was prepared via a Claisen-Schmidt condensation through a solventless, green synthesis technique. The resulting crystals formed in the monoclinic space group P21/c, and adopting the common E configuration.


Structure description
The chalcone family of compounds possess an aromatic ,-unsaturated ketone functionality and can readily be formed by base-promoted condensation-dehydrations of an aromatic aldehyde and an aromatic ketone. They are important pharmacophore scaffolds and can possess anti-inflammatory, anti-fungal, anti-cancer, and anti-malarial biological activities (Singh et al., 2015(Singh et al., , 2014Berthelette et al., 1997). Additionally, the aromatic groups can be functionalized so as to produce other biological effects. The indanone family of compounds are biologically active compounds that are involved in steroid hormone biosynthesis and arachidonic acid metabolism pathways (Berthelette et al., 1997). In addition, indanone derivatives serve as scaffolds for a variety of heterocycles (Sloop et al., 2002(Sloop et al., , 2012.
The combination of these two potential pharmacophores using greener and more efficient synthesis pathways en route to a series of highly functionalized indanone-based chalcones is now being studied by our research group. The solvent-free Claisen-Schmidt reaction undertaken in Fig. 1 minimizes reaction toxicity, limits waste production and enables easier product isolation in many cases.
In the title molecule (Fig. 2), the dihedral angle between the indanone ring system and the benzene ring is 2.54 (4) and the C'7 and C18 atoms of the methoxy groups deviate data reports from the benzene ring by 0.087 (1) and 0.114 (1) Å , respectively. No unusual bond lengths or angles are noted after a routine Mogul geometry check (Bruno et al., 2004).
The predominant supramolecular feature of this structure (Fig. 3) are slipped stacking interactions. This consists of ringover-atom pairings between the indanone ring and the 3position of the dimethoxyphenyl ring of a neighboring molecule and generates a relatively close contact of 2.7 Å for the methylene H atoms of the indanone ring to the adjacent molecule.
Structurally characterized 1b is consistent with known structures of similar indaneones.  (Zhou et al., 2009) and HAVLAR (Mori & Maeda, 1994)]. The latter has seven structure determinations as part of a light-driven solid-state isomerization study (Harada et al., 2009).

Synthesis and crystallization
A 25 mL beaker equipped with a stir bar was charged with 3,5dimethoxybenzaldehyde (0.50 g, 3.0 mmol) and warmed to 60 C. To the liquified aldehyde was added 1-indanone (0.40 g, 3.0 mmol) and solid NaOH (0.20 g, 3.8 mmol). The reaction mixture was stirred for 30 minutes at 60 C. The resulting reaction mixture was neutralized with 4 mL of 1 M HCl, the resulting residue was washed with several 1 mL aliquots of distilled water and the crude product (0.80 g, 95% yield) isolated via vacuum filtration. Recrystallization from 95% ethanol solution via slow evaporation afforded the target chalcone, (E)-2-(3,5-dimethoxybenzylidenyl)-1-indanone (1b) as colorless needles, (0.47 g, 56% yield). Melting range: 174-175 C. IR, 1 H and 13 C NMR spectroscopy and single-crystal X-ray analysis (see supporting information) confirmed the product identity.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1.

Figure 2
Displacement ellipsoid plot of 1b. Ellipsoids are drawn at the 50% probability level.

Figure 3
Packing diagram of 1b viewed along the b axis. 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. data reports data-2 IUCrData (2020). 5, x200759 Refinement. All hydrogen atoms were seen in the difference map of later refinements, but were placed at calculated positions and refined using a riding model, setting isotropic displacement parameters to 1.2 or 1.5 times that of the parent atom for ring H atoms and methyl groups respectively.