3-Ethyl-4-phen­oxy-1-(2,2,2-trifluoro­eth­yl)-1H-pyrazol-5-ol

Tara Shahani; Hoong-Kun Fun; R Venkat Ragavan; V Vijayakumar; S Sarveswari

doi:10.1107/S1600536810025948

. 2010 Jul 7;66(Pt 8):o1937–o1938. doi: 10.1107/S1600536810025948

3-Ethyl-4-phenoxy-1-(2,2,2-trifluoroethyl)-1H-pyrazol-5-ol

Tara Shahani ^a, Hoong-Kun Fun ^a,^*,^‡, R Venkat Ragavan ^b, V Vijayakumar ^b, S Sarveswari ^b

PMCID: PMC3007551 PMID: 21588264

Abstract

The title compound, C₁₃H₁₃F₃N₂O₂, crystallizes with two independent molecules in the asymmetric unit, with different conformations of their ethyl side chains. The dihedral angles formed between the 1H-pyrazole and benzene rings in the two molecules are 79.44 (6) and 77.81 (6)°. In the crystal, molecules are linked by O⋯H—N hydrogen bonds into chains propagating along [001] and the packing is further stabilized by π–π interactions [centroid–centroid separations = 3.5409 (10) and 3.6335 (10) Å].

Related literature

For the synthesis, see: Ragavan et al. (2009 ▶, 2010 ▶). For background on the biological activity of 3-ethyl-4-phenoxy-1-(2,2,2-trifluoroethyl)-1H-pyrazol-5-ol, see: Brogden (1986 ▶); Gursoy et al. (2000 ▶); Watanabe et al. (1984 ▶); Kawai et al. (1997 ▶); Wu et al. (2002 ▶). For related structures, see: Shahani et al. (2009 ▶, 2010a ▶,b ▶,c ▶,d ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶). For related literature, see: Coersmeier et al. (1986 ▶).

Experimental

Crystal data

C₁₃H₁₃F₃N₂O₂
M _r = 286.25
Monoclinic,
a = 9.3490 (18) Å
b = 14.712 (3) Å
c = 20.319 (4) Å
β = 113.889 (8)°
V = 2555.3 (9) Å³
Z = 8
Mo Kα radiation
μ = 0.13 mm⁻¹
T = 100 K
0.38 × 0.26 × 0.15 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.952, T _max = 0.981
35406 measured reflections
9653 independent reflections
7544 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.156
S = 1.07
9653 reflections
365 parameters
H-atom parameters constrained
Δρ_max = 0.68 e Å⁻³
Δρ_min = −0.55 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810025948/hb5540sup1.cif

e-66-o1937-sup1.cif^{(26.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810025948/hb5540Isup2.hkl

e-66-o1937-Isup2.hkl^{(472.1KB, hkl)}

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

Table 1. Selected torsion angles (°).

N1A—C8A—C12A—C13A	40.62 (16)
N1B—C8B—C12B—C13B	111.06 (16)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2A—H1OA⋯N1Bⁱ	0.82	1.79	2.5996 (15)	169
O2B—H1OB⋯N1Aⁱⁱ	0.82	1.76	2.5781 (14)	177

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

Acknowledgments

TS and HKF thank Universiti Sains Malaysia (USM) for the Research University Golden Goose Grant (1001/PFIZIK/8111012). TS also thanks the Research University Grant (1001/PFIZIK/811151) for the position of Graduate Research Assistant. VV is grateful to DST-India for funding through the Young Scientist Scheme (Fast Track Proposal).

supplementary crystallographic information

Comment

Pyrazolone derivatives have a broad spectrum of biological activities being used as analgesic, antipyretic and anti-inflammatory therapeutical drugs (Brogden, 1986; Gursoy et al., 2000). A class of new compounds with pyrazolone moiety was synthesized and reported for their antibacterial and antifungal activities (Ragavan et al., 2009, 2010). A new pyrazolone derivative, edaravone (3-methyl-1-phenyl-2-pyrazoline-5-one), is being used as a drug in clinical practice for brain ischemia (Watanabe et al., 1984; Kawai et al., 1997) and the same has been found to be effective against myocardial ischemia (Wu et al., 2002).

There are two independent molecules (A and B) in the asymmetric unit (Fig. 1). The maximum deviations in 1H-pyrazole rings (N1/N2/C7–C9) are 0.002 (1) and 0.003 (1) Å, respectively, for atom C7A of molecule A and atoms N2B and C8B of molecule B. The dihedral angles formed between the 1H-pyrazole rings and benzene rings in molecules A and B are 79.44 (6) and 77.81 (6)°, respectively. The bond lengths (Allen et al.,1987) and angles are within normal ranges and comparable to those closely related structures (Shahani et al., 2009, 2010a,b,c,d).

In the crystal packing (Fig. 2), intermolecular O2A···H1OA—N1B, O2B···H1OB—N1A hydrogen bonds (Table 1) link the molecules into one-dimensional chains along [001] direction. The interesting feature of the crystal packing is provided by weak π–π interactions [Cg1···Cg4 = 3.5409 (10) Å, symmetry code, 1+x, 3/2-y, -1/2+z], [Cg2···Cg3 = 3.6335 (10) Å, symmetry code, -1 + x, y, z], Cg1 and Cg4 are the centroids of the benzene rings (C1A–C6A & C1B–C6B), Cg2 and Cg3 are the centroids of the 1H-pyrazole rings (N1A/N2A/C7A–C9A & N1B/N2B/C7B–C9B).

Experimental

The title compound has been synthesized according to the available procedure in the literature (Ragavan et al., 2009, 2010) and purified by column chromatography using ethyl acetate and methanol mixture (1:99). The obtained solid was recrystallized using absolute ethanol to yield colourless blocks of (I). Yield: 49%; Mp. 463–465 K.