Crystal structure of dimethyl 1-oxo-2,4-diphenyl-1,2-dihydronaphthalene-2,3-dicarboxylate

In the title compound, a naphthalene derivative, the cyclohexa-1,3-diene ring of the 1,2-dihydronaphthalene ring system adopts a half-chair conformation. The mean plane of the 1,2-dihydronapthalene ring system make dihedral angles of 86.23 (6) and 64.80 (7)° with two phenyl rings. In the crystal, the molecules are linked by C—H⋯O, interactions and further stabilized by C—H⋯π and π–π interactions.


Figure 2
A packing diagram of the title compound, showing a C(10) zigzag chain along to the c axis formed via C-HÁ Á ÁO hydrogen bonds (dashed lines). The H atoms not involved in the hydrogen bonding have been excluded for clarity. [Symmetry code: (i) x, 3 2 À y, À 1 2 + z.]

Figure 1
The molecular structure of the title compound with the atom-numbering scheme. The displacement ellipsoids are drawn at the 30% probability level. H atoms are shown as spheres of arbitrary radii.

Synthesis and crystallization
To a solution of 1,3-diphenylisobenzofuran (1 g, 3.70 mmol) in dry dichloromethane, dimethyl acetylenedicarboxylate (0.58 g, 4.07 mmol) was added and the reaction mixture was stirred at room temperature for 1 h. Removal of solvent followed by column chromatographic purification (silica gel; 15% ethyl acetate in hexane) afforded isobenzofurandimethyl acetylenedicarboxylate adduct as a colourless solid (1.10 g, 72%). To a solution of the adduct (0.50 g, 1.21 mmol) in dry dichloromethane, BF 3 ÁOEt 2 (0.075 g, 0.52 mmol) was added and the reaction mixture was stirred at room temperature for 5 min. Removal of solvent followed by column chromatographic purification (silica gel; 15% ethyl acetate in hexane) gave the title compound as a colourless solid (0.45 g, 94%). Single crystals suitable for X-ray diffraction were prepared by slow evaporation of an ethyl acetate solution of the title compound at room temperature (m.p. = 454-456 K).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms were localized in a difference-Fourier map and then were treated as riding atoms, with C-H = 0.93 and 0.96 Å for aryl and methyl groups, respectively, and with U iso (H) = 1.2U eq (aryl C) and 1.5U eq (methyl C), allowing for free rotation of the methyl groups.   Crystal structure of dimethyl 1-oxo-2,4-diphenyl-1,2-dihydronaphthalene-2,3dicarboxylate Gajendran Jagadeesan, Immanuel Monica Chandramalar, Jayachandran Karunakaran,

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. 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 > 2sigma(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.