Ethyl 1-sec-butyl-2-(4-fluoro­phen­yl)-1H-benzimidazole-5-carboxyl­ate

Natarajan Arumugam; Nurziana Ngah; Shafida Abd Hamid; Aisyah Saad Abdul Rahim

doi:10.1107/S1600536811041663

. 2011 Oct 12;67(Pt 11):o2938. doi: 10.1107/S1600536811041663

Ethyl 1-sec-butyl-2-(4-fluorophenyl)-1H-benzimidazole-5-carboxylate

Natarajan Arumugam ^a, Nurziana Ngah ^b, Shafida Abd Hamid ^b, Aisyah Saad Abdul Rahim ^a,^*

PMCID: PMC3247350 PMID: 22219968

Abstract

In the title compound, C₂₀H₂₁FN₂O₂, the benzene ring and the benzimidazole ring system are inclined at a dihedral angle of 44.40 (9)°. In the crystal, molecules are linked by intermolecular C—H⋯O hydrogen bonds, forming a zigzag chain along the b-axis direction. An intramolecular C—H⋯π interaction is also observed.

Related literature

For the synthesis of the title compound and related structures, see: Arumugam, Abd Hamid et al. (2010 ▶); Arumugam, Abdul Rahim, Osman, Hemamalini & Fun (2010 ▶); Arumugam, Abdul Rahim, Osman, Quah & Fun (2010 ▶). For applications of benzimidazole derivatives, see: Spasov et al. (1999 ▶); Easmon et al. (2001 ▶); Özden et al. (2004 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₂₀H₂₁FN₂O₂
M _r = 340.39
Monoclinic,
a = 10.2249 (16) Å
b = 12.3767 (18) Å
c = 14.149 (2) Å
β = 93.473 (2)°
V = 1787.3 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 K
0.37 × 0.20 × 0.11 mm

Data collection

Bruker APEXII DUO CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.968, T _max = 0.990
10465 measured reflections
3130 independent reflections
2342 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.047
wR(F ²) = 0.150
S = 1.05
3130 reflections
229 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.20 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/S1600536811041663/is2787sup1.cif

e-67-o2938-sup1.cif^{(20.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811041663/is2787Isup2.hkl

e-67-o2938-Isup2.hkl^{(153.6KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811041663/is2787Isup3.cml

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

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

Cg1 is the centroid of the N1/C7/N2/C1/C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5⋯O1ⁱ	0.93	2.53	3.452 (3)	169
C20—H20C⋯O1ⁱ	0.96	2.59	3.485 (4)	154
C19—H19A⋯Cg1	0.96	2.82	3.400 (3)	121

Open in a new tab

Symmetry code: (i) Inline graphic .

Acknowledgments

NA, ASAR and SAH acknowledge Universiti Sains Malaysia (USM) for funding the synthetic chemistry work under 304/PFARMASI/650544 and 304/PFARMASI/650512. NA also thanks Universiti Sains Malaysia for the award of a postdoctoral fellowship.

supplementary crystallographic information

Comment

The synthesis of benzimidazole heterocycles is ever fascinating since they promise a wide spectrum of pharmacological activities such as antibacterial (Özden et al., 2004), anticancer (Easmon et al., 2001) and antifungal (Spasov et al., 1999). As the benzimidazole derivative is of much importance, we have undertaken the X-ray crystal structure determination of the title compound.

The title compound (Fig. 1) is similar to those previously reported ethyl-1-sec-butyl-2-(4-chlorophenyl)-1H-benzimidazole-5-carboxylate (Arumugam, Abdul Rahim, Osman, Quah & Fun, 2010) except the fluorine atom is attached at the para position of the phenyl ring. The phenyl (C8/C9/C10/ C11/C12/C13) and benzimidazole (N1/N2/C1/C2/C3/C4/C5) fragments are essentially planar with maximum deviation is 0.005 (2)Å for atom C2. Both fragments are inclined to each other by 44.40 (9)°. The bond lengths are in normal ranges (Allen et al., 1987) and in agreement to those reported by Arumugam et al. (Arumugam, Abd Hamid et al., 2010; Arumugam, Abdul Rahim, Osman, Hemamalini & Fun, 2010; Arumugam, Abdul Rahim, Osman, Quah & Fun, 2010). In the crystal structure (Fig. 2), the molecules are linked by intermolecular C5—H5···O1ⁱ and C20—H20C···O1ⁱ hydrogen bonds (symmetry codes as in Table 1) to form a zigzag chain along the b axis. The molecular structure is further stabilized by an intramolecular C—H···Cg1 (Table 1) interaction; Cg1 is the centroid of the N1/C7/N2/C1/C6 ring.

Experimental

A solution of ethyl-3-amino-4-(sec-butylamino) benzoate (1.0 mmol) and sodium bisulfite adduct of 4-fluorobenzaldehyde (3.5 mmol) in DMF was treated under microwave conditions at 130 °C for 2 minutes. The reaction mixture was diluted in EtOAc (20 ml) and washed with H₂O (20 ml). The organic layer was collected and dried with Na₂SO₄. The solvent was evaporated in vacuo to afford a crude product. Recrystallization of the crude product gave the title compound as colourless crystal.