(E)-2,2′-[3-(2-Nitrophenyl)prop-2-ene-1,1-diyl]bis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-one)

In the title compound, C25H29NO6, each of the cyclohexenone rings adopts a half-chair conformation. Each of the pairs of hydroxy and carbonyl O atoms are oriented to allow for the formation of intramolecular O—H⋯O hydrogen bonds, which are typical of xanthene derivatives. The nitro group is rotationally disordered over two orientations in a 0.544 (6):0.456 (6) ratio. In the crystal, weak intermolecualr C—H⋯O hydrogen bonds link molecules into layers parallel to the ab plane.

In the title compound, C 25 H 29 NO 6 , each of the cyclohexenone rings adopts a half-chair conformation. Each of the pairs of hydroxy and carbonyl O atoms are oriented to allow for the formation of intramolecular O-HÁ Á ÁO hydrogen bonds, which are typical of xanthene derivatives. The nitro group is rotationally disordered over two orientations in a 0.544 (6):0.456 (6) ratio. In the crystal, weak intermolecualr C-HÁ Á ÁO hydrogen bonds link molecules into layers parallel to the ab plane.  Table 1 Hydrogen-bond geometry (Å , ). Symmetry codes: (i) Àx þ 1; Ày þ 2; Àz þ 1; (ii)
Data collection: RAPID-AUTO (Rigaku, 2006); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: IL MILIONE (Burla et al., 2007); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalStructure (Rigaku, 2010); software used to prepare material for publication: CrystalStructure. Comment As a part of our ongoing study of the substituent effect on the solid state structures of Xanthene derivatives (Cha et al., 2011) we present here the crystal structure of the title compound (I) (Fig. 1).
In the crystal, weak intermolecular C-H···O hydrogen bonds (Table 1) link molecules into layers parallel to the ab plane.

Experimental
To solution of 1,3-cyclohexanedione (4.61 mmol), 2-nitrocinnamaldehyde (1.84 mmol) and 4° MS was added catalytic amounts of L-proline (0.47 mmol) in under nitrogen atmosphere. After stirring for 5 h, The anhydrous ethyl acetate (0.5 ml) was added to a reaction mixture and the solution was stirred for 3 days. The reaction mixture was filtered through pad of celite to remove MS and concentrated. The residue oil was purified by flash column chromatography to afford product which was recrystallized from ethanol to give crystals suitable for X-ray analysis.

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.93-0.98 Å and Uiso(H) = 1.2 or 1.5Ueq(C). Rotating group model was applied for the methyl groups. The nitro group was refined as disordered over two orientations. Fig. 1. The molecular structure of (I) showing the atomic numbering and 50% probability displacement ellipsoid. Only major part of the disordered nitro group is shown.