Crystal structure of 2-[2-(benzyloxy)benzylidene]malononitrile

In the title benzylidenemalononitrile derivative, C17H12N2O, the dihedral angles between the central benzene ring and the Y-shaped C=C(CN)2 group (r.m.s. deviation = 0.006 Å) and the terminal benzene ring are 12.72 (8) and 37.60 (11)°, respectively. The Car—O—Csp 3—Car torsion angle is −174.52 (13)° and the major twist between the aromatic rings occurs about the Csp 3—Car bond. Weak aromatic π–π stacking [centroid–centroid separation = 3.7784 (13) Å; slippage = 1.21 Å] between inversion-related pairs of the central benzene rings is observed in the crystal.


S1. Comment
Malononitriles and their benzylidene derivative represent a wide group of organic compounds having a number of pharmacological activities including inhibition of epidermal growth factor protein tyrosine kinas (Turpaev et al., 2011, Gazit et al., 1989, expression of iNOS and COX-2 pro-inflammatory agents. Structural analogues of benzylidenemalononitrile are also known to have free radical scavenging (Sagara et al., 2002) and antiinflammatory properties (suppression of TNFα release) (Novogrodsky et al., 1994). The title compound was obtained as a part of our ongoing resaerch to synthesize and evaluate the biological activities of structural analogues having benzylidenemalononitrile as basic nucleus.

S2. Experimental
In a round-bottomed flask 2-benzyloxybenzaldehyde (1 mmol) and a catalytic amount (3 mol%) of Bi(NO3) 3 in water/ethanol (10 ml) were stirred for 2 minutes at room temperature followed by the additon of malononitrile (1.1 mmol). The reaction mixture was refluxed for 20 minutes. After completion of the reaction (TLC analysis), Bi(NO 3 ) 3 was filtered for the next use and the filtrate was kept at room temperature over night to obtain crystals. Crystals were filtered, washed with water, dried, and re-crystallized from hot ethanol as colourless plates. Thin layer chromatography was carried out on aluminium plates pre-coated with silica gel (Kieselgel 60, E. Merck, Darmstadt, Germany). UV light at 254 and 365 nm was used for chromatograms visualization.

S3. Refinement
H atoms on phenyl and methine were positioned geometrically with C-H = 0.93 Å (CH phenyl) and 0.97 Å (CH) and constrained to ride on their parent atoms with U iso (H)=1.2U eq (CH).

Figure 1
The molecular structure of (I) with displacement ellipsoids drawn at 30% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.