rac-5-Acetyl-6-hy­droxy-3,6-dimethyl-4-phenyl-4,5,6,7-tetra­hydro-2H-indazole

Abel M Maharramov; Arif I Ismiyev; Bahruz A Rashidov; Ilkin V Aliyev

doi:10.1107/S1600536811013195

. 2011 Apr 13;67(Pt 5):o1127. doi: 10.1107/S1600536811013195

rac-5-Acetyl-6-hydroxy-3,6-dimethyl-4-phenyl-4,5,6,7-tetrahydro-2H-indazole

Abel M Maharramov ^a,^*, Arif I Ismiyev ^a, Bahruz A Rashidov ^a, Ilkin V Aliyev ^a

PMCID: PMC3089358 PMID: 21754439

Abstract

The title compound, C₁₇H₂₀N₂O₂, is chiral but crystallizes in a centrosymmetric space group as a racemate, the relative configuration at the stereogenic centres being 2S*,3R*,4S*. The cyclohexane ring adopts a half-chair conformation while the pyrazole ring has an envelope conformation. The crystal packing displays intermolecular O—H⋯N and N—H⋯O hydrogen bonding.

Related literature

For background to the use of β-cycloketols as synthons in syntheses of pyrazoles, see: Pramula et al. (1985 ▶).

Experimental

Crystal data

C₁₇H₂₀N₂O₂
M _r = 284.35
Monoclinic,
a = 18.6999 (9) Å
b = 5.6415 (3) Å
c = 28.4855 (14) Å
β = 94.498 (1)°
V = 2995.8 (3) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.30 × 0.30 × 0.20 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ▶) T _min = 0.975, T _max = 0.984
16597 measured reflections
3709 independent reflections
3079 reflections with I > 2σ(I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.129
S = 1.00
3709 reflections
193 parameters
H-atom parameters constrained
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-Plus, (Bruker, 2001 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks Global, I. DOI: 10.1107/S1600536811013195/kp2321sup1.cif

e-67-o1127-sup1.cif^{(19.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811013195/kp2321Isup2.hkl

e-67-o1127-Isup2.hkl^{(181.9KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯N1ⁱ	0.82	2.03	2.8487 (14)	178
N2—H2C⋯O1ⁱⁱ	0.86	2.11	2.9587 (15)	168

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

We thank Professor Victor N. Khrustalev for fruitful discussions and help in this work.

supplementary crystallographic information

Comment

The exploitation of a simple molecule with different functionalities for the synthesis of heterocycles is usefula approach. In fact, the β-cycloketols has been used as an effective synthon in some projected syntheses of pyrazoles (Pramula et al. 1985).

In the title compound, C₁₇H₂₀N₂O₂ (I), the cyclohexane ring adopts a half-chair conformation (Fig. 1). Cyclohexane ring has a chair conformation. The phenyl ring is in a pseudo-equatorial position. The torsion angle between the acetyl group and the phenyl substituent (C7—C2—C3—C13) is 64.88 (13) °indicating the pseudo-axial location of hydrogen atoms at C2 and C3. The crystal of (I) is racemate and consists of enantiomeric pairs where the relative configuration of the centres are 2S*,3R*,4S*. The crystal structure involves N—H···O and O—H···N intermolecular hydrogen bonds (Table 1 and Fig. 2).

Experimental

2,4-Diacetyl-5-hydroxy-5-metyl-3-phenilcyclohexanon (20 mmol), hydrazine hydrate (20 mmol) were dissolved in 20 mL ethanol. The mixture was stirred at 345–350 K for 10 h. After cooling to room temperature, white crystals were obtained. The crystals were filtered off and washed with ethanol. Then, they were dissolved in ethanol (50 mL) and recrystallised to yield colourless block-shaped crystals suitable for data collection.