Crystal structure of 3,5-dimeth­oxy-2-[5-(naphthalen-1-yl)-4,5-di­hydro-1H-pyrazol-3-yl]phenol

Dongsoo Koh

doi:10.1107/S2056989015016369

. 2015 Sep 12;71(Pt 10):o708–o709. doi: 10.1107/S2056989015016369

Crystal structure of 3,5-dimethoxy-2-[5-(naphthalen-1-yl)-4,5-dihydro-1H-pyrazol-3-yl]phenol

Dongsoo Koh ^a,^*

PMCID: PMC4647439 PMID: 26594435

Abstract

In the title compound, C₂₁H₂₀N₂O₃, the planes of the benzene ring and the naphthalene ring system are inclined to one another by 70.95°, and by 4.99 (6) and 75.93 (5)°, respectively, to the mean plane of the pyrazoline ring. The latter has an envelope conformation with the methine (CH) C atom as the flap. There is an intramolecular O—H⋯N hydrogen bond that forms an S(6) ring motif. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming chains along [100]. The chains are linked via C—H⋯N hydrogen bonds, forming sheets parallel to the ab plane. The sheets are linked by a series of N—H⋯π and C—H⋯π interactions forming a three-dimensional structure.

Keywords: crystal structure, pyrazoline, naphthalene, N—H⋯π and C—H⋯π interaction, hydrogen bonding

Related literature

For the synthesis and biological properties of pyrazoline derivatives, see: Bano et al. (2015 ▸); Viveka et al. (2015 ▸); Neudorfer et al. (2014 ▸); Hwang et al. (2013 ▸); Yong et al. (2013 ▸); Congiu et al. (2010 ▸). For N—H⋯π interactions in the crystal structure of 3-(thiophen-2-yl)-5-p-tolyl-4,5-dihydro-1H-pyrazole-1-carbothioamide, see: Naveen et al. (2015 ▸). For related structures, see: Zhu et al. (2013 ▸); Patel et al. (2013 ▸). graphic file with name e-71-0o708-scheme1.jpg

Experimental

Crystal data

C₂₁H₂₀N₂O₃
M _r = 348.39
Triclinic,
a = 7.6248 (5) Å
b = 8.6044 (6) Å
c = 13.1757 (9) Å
α = 92.832 (4)°
β = 90.777 (3)°
γ = 99.099 (3)°
V = 852.30 (10) Å³
Z = 2
Cu Kα radiation
μ = 0.74 mm⁻¹
T = 147 K
0.18 × 0.11 × 0.09 mm

Data collection

Bruker Kappa APEX DUO CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2012 ▸) T _min = 0.698, T _max = 0.753
21626 measured reflections
2906 independent reflections
2736 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.036
wR(F ²) = 0.096
S = 1.04
2906 reflections
245 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: APEX2 (Bruker, 2012 ▸); cell refinement: SAINT (Bruker, 2012 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: PLATON (Spek, 2009 ▸) and Mercury (Macrae et al., 2008 ▸); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▸) and PLATON.

Supplementary Material

Crystal structure: contains datablock(s) I, Global. DOI: 10.1107/S2056989015016369/su5198sup1.cif

e-71-0o708-sup1.cif^{(27.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015016369/su5198Isup2.hkl

e-71-0o708-Isup2.hkl^{(142.6KB, hkl)}

Click here for additional data file.^{(7.1KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015016369/su5198Isup3.cml

Click here for additional data file.^{(1.3MB, tif)}

. DOI: 10.1107/S2056989015016369/su5198fig1.tif

The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Click here for additional data file.^{(1.4MB, tif)}

c . DOI: 10.1107/S2056989015016369/su5198fig2.tif

A view along the c axis of the crystal packing of the title compound. The hydrogen bonds are shown as dashed lines (see Table 1).

Click here for additional data file.^{(975KB, tif)}

. DOI: 10.1107/S2056989015016369/su5198fig3.tif

A view of the inversion dimers formed by a pair of N-H⋯π interactions (dashed lines; see Table 1), in the crystal structure of the title compound.

Click here for additional data file.^{(20.8KB, tif)}

. DOI: 10.1107/S2056989015016369/su5198fig4.tif

Synthetic scheme for the preparation of the title pyrazoline compound.

CCDC reference: 1421849

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (, ).

Cg2, Cg3 and Cg4 are the centroids of rings C4C8/C13, C8C13 and C14C19, respectively.

DHA	DH	HA	D A	DHA
O3H3ON1	0.926(18)	1.718(18)	2.5578(12)	149.3(16)
C7H7AN2ⁱ	0.95	2.56	3.4976(16)	171
C12H12AO3ⁱⁱ	0.95	2.46	3.3663(15)	161
N2H2N Cg3ⁱⁱⁱ	0.898(17)	2.609(17)	3.1906(11)	123.2(12)
C3H3A Cg2ⁱⁱⁱ	1.00	2.84	3.5842(12)	131
C20H20C Cg4^iv	0.98	2.93	3.7892(16)	146
C21H21C Cg4^v	0.98	2.85	3.6296(17)	137

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

The author acknowledges financial support from Dongduk Women’s University.

supplementary crystallographic information

S1. Comment

Recent medicinal chemistry researches have been focused on the pyrazoline pharmarcophore. Pyrazolines show a broad spectrum of biological activities including antimicrobial (Bano et al., 2015), anti-inflammatory (Viveka et al., 2015), Alzheimer drugs (Neudorfer et al., 2014) and antitumor properties (Congiu et al., 2010). The title pyrazoline compound was synthesized, in continuation of our research program (Hwang et al., 2013), and we report herein on its crystal structure.

The molecular structure of the title compound is shown in Fig. 1. The central pyrazoline ring has an envelope conformation with atom C3 as the flap. The naphthalene and the benzene ring are inclined to the mean plane of the pyrazoline ring by 75.93 (5) and 4.99 (6) °, respectively, and by 70.95 (5) ° to one another. The methoxy group at the ortho position of the benzene is almost coplanar with the ring [C20—O1—C15—C16 = 0.8 (2) °], whereas the methoxy group at the para position of benzene is slightly twisted from the ring plane [C21—O2—C17—16 = -5.7 (2) °]. The hydroxyl group at the ortho position of the benzene ring makes an intramolecular O—H···N hydrogen bond to form an S(6)ring motif (Fig. 1 and Table 1).

In the crystal, molecules are linked by C—H···O hydrogen bonds forming chains along [100]. The chains are linked via C—H···N hydrogen bonds forming sheets parallel to the ab plane (Table 1 and Fig. 2). The sheets are linked by a series of N—H···π (Fig. 3) and C—H···π interactions (Table 1) forming a three-dimensional structure.

S2. Synthesis and crystallization

The starting material chalcone was prepared by the previously reported method (Yong et al. 2013)and the pyrazoline was obtained by cyclization reaction of the chalcone with NH₂NH₂, as illustrated in Fig. 4. To a solution of 6-methoxy-2-hydroxyacetophenone (10 mmol, 1.66g) in 50 ml of ethanol was added 2,3-dimethoxy-1-naphthaldehyde (10 mmol, 1.56g) and the temperature was adjusted to around 276-277K in an ice-bath. To the reaction mixture was added 8 ml of 50% (w/v) aqueous KOH solution and the reaction mixture was stirred at room temperature for 20 h. At the end of the reaction, ice water was added to the mixture and it was then acidified with 6N HCl (pH = 3-4). The resulting precipitate was filtered and washed with water and ethanol. The crude solid was purified by recrystallization from ethanol to give the pure chalcone starting material. Excess hydrazine monohydrate (1 ml of 64-65% solution, 13 mmol) was added to a solution of the chalcone compound (5 mmol, 1.52g) in 30 ml anhydrous ethanol, and the solution was refluxed at 360 K for 5 h. The reaction mixture was cooled to room temperature to yield a solid that was then filtered. The crude solids were purified by recrystallization from ethanol to afford the pure pyrazoline title compound as yellow needle-like crystals (yield: 93%; m.p.: 403-403K).

S3. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. The NH and OH H atoms were located in a difference Fourier map and freely refined. The C-bound H atoms were placed in calculated positions and included in the refinement in a riding-model approximation: C–H = 0.95–1.00 Å with U_iso(H) = 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C) for other H atoms.