4,5,7-Trimethoxy-2-methyl-3-(2,4,5-trimethoxyphenyl)-1-[3-(2,4,5-trimethoxyphenyl)pentan-2-yl]indane acetone 0.858-solvate

In the title compound, C36H48O9.0.858C3H6O, the five-membered ring adopts an envelope conformation. The acetone solvent molecule was disordered and was refined over two positions with equal occupancies, giving an overall occupancy of 0.858 (4). There are weak intramolecular C—H⋯O hydrogen bonds and intermolecular C—H⋯π interactions in the structure.

The benzene ring (C4 to C9) is almost perpendicular to the other two benzene rings (C10 to C15; C18 to C23) with the interplanar angles of 85.05 (9) and 77.58 (7)°, respectively, while the interplanar angle between the benzene rings (C10 to C15 and C18 to C23) equals to 61.31 (10)°. As shown in Fig. 3, the acetone solvate was disordered and it was refined in two positions with equal occupancies giving the overall occupancy 0.858 (4). This means that the content of acetone is lesser than that of asarone trimer, or in other words, that in some unit cells the acetone molecule is not present. The molecular and crystal structure of the title compound is stabilized by intramolecular weak C-H···O hydrogen bonds and C-H···π-ring electron interactions (Table 1).

Experimental
In the α-asarone preparation from 2,4,5-trimethoxybenzaldehyde (Xu et al., 2009), the crude product, containing α-asarone, asarone dimers and asarone trimer and other unknown impurities, was dissolved in hot EtOH/H 2 O (V:V 7:3), and then cooled and filtrated. The yellow powder, obtained by concentrating of the filtrate in vacuo, was dissolved again in EtOH/H 2 O (V:V 7:3), and then cooled and filtrated. The filtrate afforded a yellow oil after removal of the solvents under reduced pressure.

Refinement
All the H atoms were placed into the calculated idealized positions, with C-H = 0.98 (methine), 0.97 (methylene), 0.96 (methyl) and 0.93 Å (aryl), and were treated in riding mode approximation. (The methyl groups were checked in the difference electron density maps and allowed to rotate freely about their axes.) U iso (H)=1.5U eq C methyl or U iso (H)=1.3U eq C methylene /C methine / aryl . The acetone solvate appeared to be disordered, and it was refined in two positions.
Its occupancy was also refined with assumed equal occupancy at each position because of the proximity of both disordered parts. The following restraints for the disordered acetones have been used: C=O distance was restrained to 1.207 (2) Å; the distances between the neighbour carbons were restrained to 1.344 (2) Å. The displacement parameters of the corresponding atoms were restrained by SIMU 0.05 0.05 for the pairs of the atoms C38A C38B; C39A C39B; O36A O36B; C37A C37B.
Figures Fig. 1. The title molecule without the acetone solvate. The displacement ellipsoids are drawn at the 30% probability level. Fig. 2. The title molecule with the disordered acetone solvate. The displacement ellipsoids are drawn at the 30% probability level.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.