rac-1-[6-Hydroxy-4-(4-methoxyphenyl)-3,6-dimethyl-4,5,6,7-tetrahydro-2H-indazol-5-yl]ethanone

The title compound, C18H22N2O3, represents a (4S,5R,6S)-stereoisomer, crystallizing as a racemate in a centrosymmetric space group. The six-membered aliphatic ring adopts a half-chair conformation, with the hydroxy- and acetyl-substituted C atoms deviating by 0.458 (2) and −0.366 (2) Å, respectively, from the plane defined by other four ring atoms. The pyrazole ring is essentially planar [r.m.s deviation = 0.004 (2) Å]. In the crystal, the molecules are linked into chains along the b axis by N—H⋯N hydrogen bonds. The chains are linked by O—H⋯N hydrogen bonds into layers parallel to the bc plane.

The title compound, C 18 H 22 N 2 O 3 , represents a (4S,5R,6S)stereoisomer, crystallizing as a racemate in a centrosymmetric space group. The six-membered aliphatic ring adopts a halfchair conformation, with the hydroxy-and acetyl-substituted C atoms deviating by 0.458 (2) and À0.366 (2) Å , respectively, from the plane defined by other four ring atoms. The pyrazole ring is essentially planar [r.m.s deviation = 0.004 (2) Å ]. In the crystal, the molecules are linked into chains along the b axis by N-HÁ Á ÁN hydrogen bonds. The chains are linked by O-HÁ Á ÁN hydrogen bonds into layers parallel to the bc plane.
supplementary materials Acta Cryst. (2013) has a half-chair conformation. Four atoms of a six-membered ring C 1 ,C 2 , C 5 , C 6 are located on the same plane within 0.004 (2) Å while C 3 (+ 0.458 (2) Å) and C 4 (-0.366 (2) Å) atoms are deviating to the opposite sides of the plane. The pyrazole ring is essentially planar (r.m.s deviation is 0.004 (2) Å). Hydrogen bonds N-H ··· N combine molecules into chains oriented along the axis b (Fig.2). H-bonds O-H ··· N form centrosymmetric cycles. Through these cycles, the above chains are combined into two-dimensional layers parallel to the plane bc.
Experimental 2,4-Diacetyl-5-hydroxy-5-metyl-3(4-methoxyphenyl)cyclohexanone (20 mmol) and hydrazine hydrate (20 mmol) were dissolved in 20 ml of ethanol. The mixture was stirred at 335-340 K for 10 h. After cooling to the room temperature, white crystals were obtained. The crystals were filtered off and washed with cold ethanol. Then they were dissolved in ethanol (50 ml) and recrystallized to yield colourless block-shaped crystals suitable for data collection.

Refinement
Hydrogen atoms of the OH and NH group found in difference-Fourier maps and included in the refinement with isotropic displacement parameters. The other hydrogen atoms were placed in calculated positions with and refined in the riding mode with isotropic displacement parameters restricted to 1.2U eq of the adjacent C atom (1.5U eq for methyl C atoms). The molecular structure of the title compound with the atomic numbering scheme. Non-essential H-atoms were removed for clarity. Displacement ellipsoids were drawn at 50% probability.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.