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Acta Cryst. (2010). E66, o2228    [ doi:10.1107/S1600536810030643 ]

Ethyl 1-tert-butyl-5-phenyl-1H-pyrazole-4-carboxylate

H.-K. Fun, C. K. Quah, B. Chandrakantha, A. M. Isloor and P. Shetty

Abstract top

In the title compound, C16H20N2O2, the pyrazole ring is essentially planar [maximum deviation = 0.008 (2) Å] and is inclined at an angle of 82.82 (10)° with respect to the phenyl ring. The crystal packing is consolidated by pairs of intermolecular C-H...O hydrogen bonds, which link the molecules into centrosymmetric dimers stacked along the a axis.

Comment top

Pyrazole and its derivatives represent one of the most active classes of compounds possessing a wide spectrum of biological activities. During the past years, considerable evidences have been accumulated to demonstrate the efficacy of pyrazole derivatives including antibacterial (Isloor et al., 2009), antifungal (Lambert & Fowler, 2005), herbicidal (Lan et al., 1999), insecticidal and other biological activities. Keeping in view of the importance of the pyrazole derivatives, we have synthesized a new pyrazole molecule, with the aim of studying its single crystal structure.

The title molecule (Fig. 1) consists of a phenyl ring (C1-C6), a tert-butyl moiety (C10-C13) and a ethyl carboxylate moiety (O1/O2/C14-C16) attached to a pyrazole ring (N1/N2/C7-C9). The pyrazole ring is essentially planar (maximum deviation = 0.008 (2) Å for atom N2) and is inclined at an angle of 82.82 (10)° with the phenyl ring. Bond lengths and angles are within normal ranges, and comparable to closely related structures (Fun et al., 2009,2010a,b).

In the crystal structure (Fig. 2), the crystal packing is consolidated by pairs of intermolecular C15—H15B···O2 hydrogen bonds linking the molecules into centrosymmetric dimers which are stacked down the a axis.

Related literature top

For general background to pyrazole derivatives and their biological activity, see: Isloor et al. (2009); Lambert & Fowler (2005); Lan et al. (1999). For related structures, see: Fun et al. (2009; 2010a,b). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

Experimental top

A mixture of ethyl-3-(dimethylamino)-2-(phenylcarbonyl)prop-2-enoate (2.0 g, 0.0080 mol), tert-butyl hydrazine.HCl (1.09 g, 0.0088 mol) and sodium bicarbonate (2.05 g, 0.0240 mol) in absolute ethanol (25 ml) was refluxed for 2 h. Reaction completion was monitored through thin layer chromatography and the reaction mixture was evaporated under reduced pressure. The residue was stirred with 1.5N HCl and the solid separated was filtered and dried under vacuum. The solid obtained was purified by column chromatography using silica gel 60-120 mesh size and petroleum ether-ethyl acetate as eluent to afford title compound as yellow solid (1.5g, 71%); melting point 343-347 K.

Refinement top

All H atoms were positioned geometrically and refined using a riding model with C-H = 0.93-0.97 Å and Uiso(H) = 1.2 or 1.5 Ueq(C). A rotating-group model was applied for the methyl groups.

Computing details top

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

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme.
[Figure 2] Fig. 2. The crystal structure of the title compound, viewed along the a axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.
Ethyl 1-tert-butyl-5-phenyl-1H-pyrazole-4-carboxylate top
Crystal data top
C16H20N2O2Z = 2
Mr = 272.34F(000) = 292
Triclinic, P1Dx = 1.251 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 9.0665 (2) ÅCell parameters from 6289 reflections
b = 9.3351 (2) Åθ = 2.4–34.3°
c = 10.5408 (3) ŵ = 0.08 mm−1
α = 110.450 (1)°T = 100 K
β = 113.987 (1)°Needle, yellow
γ = 97.645 (2)°0.41 × 0.20 × 0.12 mm
V = 723.22 (3) Å3
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		2655 independent reflections
Radiation source: fine-focus sealed tube2179 reflections with I > 2σ(I)
graphiteRint = 0.038
φ and ω scansθmax = 25.5°, θmin = 2.4°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)		h = −10→10
Tmin = 0.967, Tmax = 0.990k = −11→11
12406 measured reflectionsl = −12→12
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.099H-atom parameters constrained
S = 1.04 w = 1/[σ2(Fo2) + (0.0402P)2 + 0.3388P]
where P = (Fo2 + 2Fc2)/3
2655 reflections(Δ/σ)max = 0.001
185 parametersΔρmax = 0.22 e Å−3
0 restraintsΔρmin = −0.20 e Å−3
Crystal data top
C16H20N2O2γ = 97.645 (2)°
Mr = 272.34V = 723.22 (3) Å3
Triclinic, P1Z = 2
a = 9.0665 (2) ÅMo Kα radiation
b = 9.3351 (2) ŵ = 0.08 mm−1
c = 10.5408 (3) ÅT = 100 K
α = 110.450 (1)°0.41 × 0.20 × 0.12 mm
β = 113.987 (1)°
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		2655 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)		2179 reflections with I > 2σ(I)
Tmin = 0.967, Tmax = 0.990Rint = 0.038
12406 measured reflectionsθmax = 25.5°
Refinement top
R[F2 > 2σ(F2)] = 0.042H-atom parameters constrained
wR(F2) = 0.099Δρmax = 0.22 e Å−3
S = 1.04Δρmin = −0.20 e Å−3
2655 reflectionsAbsolute structure: ?
185 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.53056 (13)0.32289 (13)0.13622 (12)0.0190 (3)
O20.52454 (14)0.14419 (13)0.23468 (13)0.0247 (3)
N10.85134 (17)0.68033 (16)0.57591 (15)0.0199 (3)
N20.87235 (16)0.58254 (15)0.64872 (15)0.0169 (3)
C10.8628 (2)0.18877 (19)0.56614 (19)0.0203 (4)
H1A0.93340.20790.52590.024*
C20.8544 (2)0.0604 (2)0.60345 (19)0.0223 (4)
H2A0.9206−0.00530.58950.027*
C30.7477 (2)0.02988 (19)0.66145 (19)0.0216 (4)
H3A0.7430−0.05570.68720.026*
C40.6484 (2)0.12657 (19)0.68093 (19)0.0209 (4)
H4A0.57540.10500.71830.025*
C50.65692 (19)0.25632 (19)0.64487 (18)0.0187 (4)
H5A0.58990.32130.65830.022*
C60.76584 (19)0.28886 (19)0.58869 (18)0.0166 (4)
C70.77480 (19)0.42591 (18)0.54764 (18)0.0160 (3)
C80.69038 (19)0.42220 (19)0.40266 (18)0.0166 (4)
C90.7435 (2)0.58270 (19)0.42835 (19)0.0190 (4)
H9A0.70700.61630.35070.023*
C100.98019 (19)0.66369 (19)0.82223 (18)0.0178 (4)
C110.8627 (2)0.6922 (2)0.89211 (19)0.0233 (4)
H11A0.79590.75350.85270.035*
H11B0.92990.75081.00300.035*
H11C0.78840.59020.86460.035*
C121.0849 (2)0.5612 (2)0.87611 (19)0.0213 (4)
H12A1.14840.53650.82190.032*
H12B1.01010.46280.85480.032*
H12C1.16230.61990.98560.032*
C131.1020 (2)0.8262 (2)0.8701 (2)0.0232 (4)
H13A1.03760.89440.84280.035*
H13B1.16780.80910.81750.035*
H13C1.17710.87680.98020.035*
C140.57491 (19)0.2808 (2)0.25368 (19)0.0178 (4)
C150.4271 (2)0.19063 (19)−0.01920 (18)0.0204 (4)
H15A0.32690.1272−0.02750.024*
H15B0.49210.1206−0.04220.024*
C160.3759 (2)0.2633 (2)−0.1304 (2)0.0261 (4)
H16A0.31370.1788−0.23480.039*
H16B0.47590.3313−0.11640.039*
H16C0.30510.3263−0.11120.039*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0228 (6)0.0165 (6)0.0116 (6)0.0008 (5)0.0054 (5)0.0054 (5)
O20.0322 (6)0.0163 (7)0.0189 (7)−0.0002 (5)0.0098 (5)0.0070 (5)
N10.0249 (7)0.0164 (7)0.0176 (8)0.0037 (6)0.0089 (6)0.0094 (6)
N20.0197 (7)0.0145 (7)0.0143 (7)0.0020 (6)0.0070 (6)0.0070 (6)
C10.0222 (8)0.0189 (9)0.0181 (9)0.0033 (7)0.0100 (7)0.0075 (7)
C20.0250 (8)0.0169 (9)0.0211 (9)0.0067 (7)0.0085 (8)0.0076 (7)
C30.0262 (8)0.0142 (9)0.0164 (9)0.0001 (7)0.0043 (7)0.0080 (7)
C40.0222 (8)0.0193 (9)0.0156 (9)−0.0014 (7)0.0075 (7)0.0069 (7)
C50.0191 (8)0.0159 (9)0.0159 (9)0.0021 (7)0.0069 (7)0.0047 (7)
C60.0179 (7)0.0134 (8)0.0098 (8)−0.0009 (6)0.0022 (6)0.0035 (6)
C70.0163 (7)0.0142 (9)0.0161 (8)0.0028 (6)0.0088 (7)0.0049 (7)
C80.0185 (8)0.0170 (9)0.0151 (8)0.0046 (7)0.0088 (7)0.0077 (7)
C90.0227 (8)0.0189 (9)0.0153 (9)0.0044 (7)0.0082 (7)0.0095 (7)
C100.0192 (8)0.0158 (9)0.0124 (8)0.0013 (7)0.0057 (7)0.0039 (7)
C110.0243 (8)0.0228 (10)0.0180 (9)0.0039 (7)0.0099 (7)0.0061 (8)
C120.0230 (8)0.0194 (9)0.0140 (9)0.0025 (7)0.0051 (7)0.0059 (7)
C130.0220 (8)0.0198 (9)0.0189 (9)0.0001 (7)0.0058 (7)0.0067 (7)
C140.0182 (7)0.0201 (9)0.0168 (9)0.0050 (7)0.0093 (7)0.0095 (7)
C150.0224 (8)0.0170 (9)0.0135 (9)0.0013 (7)0.0059 (7)0.0034 (7)
C160.0282 (9)0.0258 (10)0.0173 (9)0.0050 (8)0.0076 (8)0.0079 (8)
Geometric parameters (Å, °) top
O1—C141.3511 (18)C8—C141.467 (2)
O1—C151.4550 (18)C9—H9A0.93
O2—C141.2116 (18)C10—C121.524 (2)
N1—C91.320 (2)C10—C111.524 (2)
N1—N21.3695 (17)C10—C131.530 (2)
N2—C71.363 (2)C11—H11A0.96
N2—C101.502 (2)C11—H11B0.96
C1—C21.388 (2)C11—H11C0.96
C1—C61.391 (2)C12—H12A0.96
C1—H1A0.93C12—H12B0.96
C2—C31.386 (2)C12—H12C0.96
C2—H2A0.93C13—H13A0.96
C3—C41.380 (2)C13—H13B0.96
C3—H3A0.93C13—H13C0.96
C4—C51.392 (2)C15—C161.499 (2)
C4—H4A0.93C15—H15A0.97
C5—C61.393 (2)C15—H15B0.97
C5—H5A0.93C16—H16A0.96
C6—C71.489 (2)C16—H16B0.96
C7—C81.388 (2)C16—H16C0.96
C8—C91.403 (2)
C14—O1—C15115.77 (12)C12—C10—C13108.71 (13)
C9—N1—N2105.07 (12)C11—C10—C13109.39 (14)
C7—N2—N1111.67 (12)C10—C11—H11A109.5
C7—N2—C10131.06 (13)C10—C11—H11B109.5
N1—N2—C10116.93 (12)H11A—C11—H11B109.5
C2—C1—C6120.21 (15)C10—C11—H11C109.5
C2—C1—H1A119.9H11A—C11—H11C109.5
C6—C1—H1A119.9H11B—C11—H11C109.5
C3—C2—C1120.18 (16)C10—C12—H12A109.5
C3—C2—H2A119.9C10—C12—H12B109.5
C1—C2—H2A119.9H12A—C12—H12B109.5
C4—C3—C2119.92 (15)C10—C12—H12C109.5
C4—C3—H3A120.0H12A—C12—H12C109.5
C2—C3—H3A120.0H12B—C12—H12C109.5
C3—C4—C5120.25 (15)C10—C13—H13A109.5
C3—C4—H4A119.9C10—C13—H13B109.5
C5—C4—H4A119.9H13A—C13—H13B109.5
C4—C5—C6120.01 (15)C10—C13—H13C109.5
C4—C5—H5A120.0H13A—C13—H13C109.5
C6—C5—H5A120.0H13B—C13—H13C109.5
C1—C6—C5119.40 (14)O2—C14—O1123.37 (14)
C1—C6—C7119.91 (14)O2—C14—C8126.18 (14)
C5—C6—C7120.65 (14)O1—C14—C8110.45 (13)
N2—C7—C8106.22 (13)O1—C15—C16107.43 (13)
N2—C7—C6125.57 (14)O1—C15—H15A110.2
C8—C7—C6128.21 (14)C16—C15—H15A110.2
C7—C8—C9105.09 (14)O1—C15—H15B110.2
C7—C8—C14127.70 (14)C16—C15—H15B110.2
C9—C8—C14127.19 (14)H15A—C15—H15B108.5
N1—C9—C8111.93 (14)C15—C16—H16A109.5
N1—C9—H9A124.0C15—C16—H16B109.5
C8—C9—H9A124.0H16A—C16—H16B109.5
N2—C10—C12110.47 (13)C15—C16—H16C109.5
N2—C10—C11108.18 (12)H16A—C16—H16C109.5
C12—C10—C11111.78 (13)H16B—C16—H16C109.5
N2—C10—C13108.24 (12)
C9—N1—N2—C7−1.56 (17)C6—C7—C8—C9−179.96 (15)
C9—N1—N2—C10−175.57 (13)N2—C7—C8—C14177.44 (15)
C6—C1—C2—C30.9 (2)C6—C7—C8—C14−1.8 (3)
C1—C2—C3—C40.5 (2)N2—N1—C9—C81.04 (18)
C2—C3—C4—C5−1.0 (2)C7—C8—C9—N1−0.18 (18)
C3—C4—C5—C60.1 (2)C14—C8—C9—N1−178.40 (15)
C2—C1—C6—C5−1.8 (2)C7—N2—C10—C1244.2 (2)
C2—C1—C6—C7−179.70 (15)N1—N2—C10—C12−143.23 (13)
C4—C5—C6—C11.3 (2)C7—N2—C10—C11−78.5 (2)
C4—C5—C6—C7179.20 (14)N1—N2—C10—C1194.12 (15)
N1—N2—C7—C81.46 (17)C7—N2—C10—C13163.07 (15)
C10—N2—C7—C8174.38 (15)N1—N2—C10—C13−24.31 (18)
N1—N2—C7—C6−179.31 (14)C15—O1—C14—O2−4.6 (2)
C10—N2—C7—C6−6.4 (3)C15—O1—C14—C8175.15 (12)
C1—C6—C7—N2−97.7 (2)C7—C8—C14—O25.7 (3)
C5—C6—C7—N284.4 (2)C9—C8—C14—O2−176.47 (16)
C1—C6—C7—C881.3 (2)C7—C8—C14—O1−174.06 (14)
C5—C6—C7—C8−96.5 (2)C9—C8—C14—O13.8 (2)
N2—C7—C8—C9−0.76 (17)C14—O1—C15—C16173.80 (13)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C15—H15B···O2i0.972.533.367 (2)145
Symmetry codes: (i) −x+1, −y, −z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C15—H15B···O2i0.972.533.367 (2)145
Symmetry codes: (i) −x+1, −y, −z.
Acknowledgements top

The authors thank Universiti Sains Malaysia (USM) for the Research University Golden Goose Grant (No. 1001/PFIZIK/811012). CKQ also thanks USM for the award of a USM fellowship. AMI is thankful to the Director, National Institute of Technology-Karnataka, Surathkal, India, for providing research facilities and for his encouragement.

references
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