9-(2-Hydroxy-6-oxocyclohex-1-en-1-yl)-2,3,4,9-tetrahydro-1H-xanthen-1-one

In the xanthene ring system in the title compound, C19H18O4, the 4H-pyran ring has a maximum deviation of 0.110 (2) Å from planarity and the cyclohexene ring exhibits a puckered conformation [puckering parameters Q T = 0.452 (3) Å, θ = 57.0 (4) and ϕ = 131.7 (4)°]. The cyclohexene ring attached to the xanthene system adopts an envelope conformation, with the middle of the three methylene C atoms as the flap atom. In the crystal, O—H⋯O and C—H⋯O hydrogen bonds form infinite chains of R 1 2(6) ring motifs along [100] with the xanthene groups arranged in an alternating zigzag manner.

In the xanthene ring system in the title compound, C 19 H 18 O 4 , the 4H-pyran ring has a maximum deviation of 0.110 (2) Å from planarity and the cyclohexene ring exhibits a puckered conformation [puckering parameters Q T = 0.452 (3) Å , = 57.0 (4) and ' = 131.7 (4) ]. The cyclohexene ring attached to the xanthene system adopts an envelope conformation, with the middle of the three methylene C atoms as the flap atom. In the crystal, O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds form infinite chains of R 1 2 (6) ring motifs along [100] with the xanthene groups arranged in an alternating zigzag manner.
Manchester Metropolitan University, Universitä t Paderborn, Erciyes University and Quaid-I-Azam University are gratefully acknowledged for supporting this study.  (Menchen et al., 2003) in addition to their fungicidal, bactericidal and anti-inflammatory possessions (Mohamed et al., 2012a;Mo et al., 2010). As part of our on-going study on synthesis of potential biologically active molecules based xanthene core structure compounds, herein we report the synthesis and structural study of the title compound.

Experimental
The title compound was obtained as a major product from a three component reaction of 112 mg (1 mmol) cyclohexane-1,3-dione, 112 mg(1 mmol)salicylaldehyde and 137 mg (1 mmol) 1-(3-aminophenyl)ethanol in 50 ml ethanol [the amino alcohol in this reaction has not been reacted instead acted as a Lewis base catalyst]. The reaction mixture was refluxed for 3 h at 350 K, then cooled at room temperature in fume cupboard where the excess solvent was evaporated.
The solid that formed was filtered off, washed with cold ethanol and dried under vacuum. On crystallization from ethanol shiny crystals (m.p. 503 K) were collected in an excellent yield (92%). Crystals suitable for X-ray diffraction were grown by slow evaporation method over two days using ethanol solution.

Refinement
All H atoms were positioned geometrically and refined as riding on their parent atoms with O-H = 0.84 Å, C-H = 0.95-1.00 Å and U iso (H) = 1.5U eq (O) for hydroxyl H or 1.2U eq (C) for other H atoms. The H atom of the hydroxyl group was placed using the rotating group refinement option (AFIX 147). Missing symmetry was checked using ADDSYM feature in PLATON (Spek, 2009). Friedel pairs were merged by using MERG 3 instruction.

Figure 1
Molecular structure of title compound. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
The intermolecular hydrogen bonds in (I) indicated as dashed lines along [001]. H-atoms not involved in hydrogen bonding are omitted.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.