Crystal structure of dimethyl 5-(4-ethylphenyl)-4-[(4-ethylphenyl)ethynyl]-6,11-diphenyl-1,3,6,11-tetrahydro-2H-6,11-epoxycyclopenta[a]anthracene-2,2-dicarboxylate

In the fused ring of the title compound, C51H42O5, all of the five-membered rings are in an envelope conformation. The dihedral angle between the benzene rings attached to the fused ring is 74.66 (7)o.


Chemical context
The hexadehydro-Diels-Alder reaction, by which benzyne intermediates (Niu et al., 2013) as well as highly functionalized benzenoid products (Karmakar et al., 2013) are prepared, has played a very significant role in the field of organic synthesis. Zhang et al. (2015) observed that benzyne intermediates can be captured by five-membered heterocyclic compounds, such as furans, pyrroles and thiophenes. As part of our work on the application of the hexadehydro-Diels-Alder reaction (Meng et al., 2017), we report herein the synthesis and crystal structure of the title compound.

Figure 2
A packing diagram of the title compound, viewed along the c axis. The C-HÁ Á Á interactions are shown as dashed lines.

Figure 3
(a) The Hirshfeld surface mapped over d norm in the range À0.260 (red) to 1.846 (blue) a.u., and (b) the Hirshfeld surface mapped over shape-index.

Figure 1
The molecular structure of the title compound, with atom labels and displacement ellipsoids drawn at the 50% probability level. H atoms are shown as small circles of arbitrary radii.

Refinement
Crystal data, data collection and structure refinement details are summarized in     model, with U iso (H) = 1.5 or 1.2U eq (C). The ethyl group (C46-C47) was found to be disordered over two sites around the C43-C46 bond axis and the occupancies were refined to 0.548 (9) and 0.452 (9). For the two ethyl groups (C36-C37 and C46-C47), displacement restraints (DELU and SIMU) were applied. For the disordered atoms (C47 and C47A), ISOR restraint and EADP constraint were also applied. Data collection: APEX2 (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHLEXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).   (14) 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.