1-(6-Fluoro-1,3-benzothia­zol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde

Hoong-Kun Fun; Chin Wei Ooi; D Munirajasekhar; M Himaja; B K Sarojini

doi:10.1107/S1600536811049634

. 2011 Nov 30;67(Pt 12):o3458–o3459. doi: 10.1107/S1600536811049634

1-(6-Fluoro-1,3-benzothiazol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde

Hoong-Kun Fun ^a,^*,^‡, Chin Wei Ooi ^a, D Munirajasekhar ^b, M Himaja ^b, B K Sarojini ^c

PMCID: PMC3239088 PMID: 22199936

Abstract

The asymmetric unit of the title compound, C₁₇H₁₀FN₃OS, consists of two crystallographically independent molecules. In one molecule, the pyrazole ring makes dihedral angles of 6.51 (7) and 34.02 (9)°, respectively, with the terminal 1,3-benzothiazole ring system and the phenyl ring, while in the other molecule these values are 6.41 (8) and 23.06 (9)°. In the crystal, the molecules are linked by weak π–π [centroid–centroid distance = 3.7069 (10) Å] and C—H⋯π interactions.

Related literature

For the biological activity of benzothiazole derivatives, see: Al-Soud et al. (2006 ▶); Kini et al. (2007 ▶); Munirajasekhar et al. (2011 ▶); Gurupadayya et al. (2008 ▶); Bowyer et al. (2007 ▶); Mittal et al. (2007 ▶); Rocío Pozas et al. (2005 ▶); Rana et al. (2008 ▶). For a related structure, see: Fun et al. (2011 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₁₇H₁₀FN₃OS
M _r = 323.34
Triclinic,
a = 8.0994 (3) Å
b = 13.6566 (4) Å
c = 13.8472 (5) Å
α = 70.393 (1)°
β = 85.264 (1)°
γ = 89.069 (1)°
V = 1437.80 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.24 mm⁻¹
T = 296 K
0.50 × 0.42 × 0.23 mm

Data collection

Bruker APEX DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.887, T _max = 0.945
31117 measured reflections
8251 independent reflections
6347 reflections with I > 2σ(I)
R _int = 0.024

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.144
S = 1.07
8251 reflections
415 parameters
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.24 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 datablock(s) global, I. DOI: 10.1107/S1600536811049634/is5013sup1.cif

e-67-o3458-sup1.cif^{(28KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811049634/is5013Isup2.hkl

e-67-o3458-Isup2.hkl^{(403.6KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811049634/is5013Isup3.cml

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

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

Cg4 is the centroid of the C11B–C16B ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5B—H5BA⋯Cg4ⁱ	0.93	2.85	3.4757 (19)	126

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Symmetry code: (i) Inline graphic .

Acknowledgments

HKF and CWO thank Universiti Sains Malaysia (USM) for the Research University Grant (1001/PFIZIK/811160). CWO also thanks the Malaysian Government and USM for the award of the post of research assistant under the Research University Grant (1001/PFIZIK/811151). HM gratefully acknowledges the School of Advanced Sciences, VIT University, Vellore, for providing facilities to carry out research.

supplementary crystallographic information

Comment

Benzothiazoles are very important bicyclic ring compounds which are of great interest because of their biological activities. The substituted benzothiazole derivatives have emerged as significant components in various diversified therapeutic applications. The literature review reveals that benzothiazoles and their derivatives show considerable activity including potent inhibition of human immunodeficiency virus type 1 (HIV-1) replication by HIV-1 protease inhibition (Al-Soud et al., 2006), antitumor (Kini et al., 2007), anthelmintic (Munirajasekhar et al., 2011) analgesic and anti-inflammatory (Gurupadayya et al., 2008), antimalarial (Bowyer et al., 2007), antifungal (Mittal et al., 2007), anticandidous (Rocío Pozas et al., 2005) as well as various CNS activities (Rana et al., 2008). The structure of 2-[5-(4-methoxyphenyl)-3-phenyl-4,5- dihydro-1H-pyrazol-1-yl]-6-methyl-1,3-benzothiazole has been reported by Fun et al. (2011). The present work describes the synthesis and crystal structure of the title compound, 1-(6-fluorobenzo-1,3-thiazol-2-yl)-3-phenyl-1H-pyrazole-4- carbaldehyde which was prepared from the reaction of 1-(6-fluoro-1,3-benzothiazol-2-yl)-2-(1-phenylethylidene)hydrazine treated with Vilsmeier-Haack reagent to obtain crystals of the title compound.

The asymmetric unit of the title compound consists of two crystallographically independent molecules A and B as shown in Fig. 1. The pyrazole rings (N2A/N3A/C8A–C10A and N2B/N3B/C8B–C10B) are approximately planar with a maximum deviation of 0.002 (2) Å for atom C8A and 0.001 (2) Å for atom C9B. The central pyrazole (N2/N3/C8–C10) ring makes dihedral angles of 6.51 (7) and 34.02 (9)°, respectively, with the terminal benzo[d]thiazole ring (S1/N1/C1–C7) system and the phenyl ring (C11–C16) for molecule A. These values are 6.41 (8) and 23.06 (9)° for molecule B. The bond lengths (Allen et al., 1987) and angles are within normal ranges and are comparable to the related structure (Fun et al., 2011).

In the crystal structure (Fig. 2), no classical hydrogen bonds were observed and stabilization is provided by a weak π–π interaction between the thiazoline (S1A/N1A/C1A/C6A–C7A) and the phenyl ring (C11B–C16B) [centroid-to-centroid (-1 + x, y, z) distance = 3.7069 (10) Å]. The structure is further stabilized by C—H···π interactions, involving the centroid of phenyl ring (C11B–C16B; Cg4; Table 1).

Experimental

1-(6-Fluorobenzo[d]thiazol-2-yl)-2-(1-phenylethylidene)hydrazine was treated with Vilsmeier-Haack reagent (DMF/POCl₃: 10:1.1 ml) and was stirred at 60–65 °C for 2.5 h. It was poured into cold water and the solid that separated out by neutralization with NaHCO₃ was filtered, washed with water and was then purified by column chromatography. The product was recrystallized from petroleum ether and ethyl acetate (80: 20) to yield block-shaped colorless crystals.