Ethyl 1-sec-butyl-2-p-tolyl-1H-benzimidazole-5-carboxyl­ate

Natarajan Arumugam; Aisyah Saad Abdul Rahim; Hasnah Osman; Chin Sing Yeap; Hoong-Kun Fun

doi:10.1107/S1600536810015242

. 2010 Apr 30;66(Pt 5):o1214–o1215. doi: 10.1107/S1600536810015242

Ethyl 1-sec-butyl-2-p-tolyl-1H-benzimidazole-5-carboxylate

Natarajan Arumugam ^a, Aisyah Saad Abdul Rahim ^a,^‡, Hasnah Osman ^b, Chin Sing Yeap ^c,^§, Hoong-Kun Fun ^c,^*,^¶

PMCID: PMC2979236 PMID: 21579242

Abstract

In the title compound, C₂₁H₂₄N₂O₂, the butyl group is disordered over two orientations with refined site occupancies of 0.883 (3) and 0.117 (3). The dihedral angle between the mean plane of benzimidazole ring system and the benzene ring is 39.32 (4)° and the dihedral angle between the mean plane of carboxylate group and the benzimidazole ring system is 6.87 (5)°. A weak intramolecular C—H⋯π interaction may have some influence on the conformation of the molecule. In the crystal structure, molecules are linked into infinite chains along the b axis by weak intermolecular C—H⋯O hydrogen bonds.

Related literature

For background information on benzimidazole derivatives, their biological activity and medical applications, see: Richter (1997 ▶); Can-Eke et al. (1998 ▶); Evans et al. (1997 ▶); Garuti et al. (2000 ▶); Sondhi et al. (2005 ▶). For the synthesis of the title compound and related structures, see: Arumugam et al. (2010a ▶,b ▶,c ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₂₁H₂₄N₂O₂
M _r = 336.42
Monoclinic,
a = 10.6093 (7) Å
b = 12.5617 (9) Å
c = 13.6025 (10) Å
β = 96.412 (2)°
V = 1801.5 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 100 K
0.46 × 0.29 × 0.24 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.964, T _max = 0.981
31247 measured reflections
8425 independent reflections
6598 reflections with I > 2σ(I)
R _int = 0.050

Refinement

R[F ² > 2σ(F ²)] = 0.051
wR(F ²) = 0.177
S = 1.08
8425 reflections
249 parameters
H-atom parameters constrained
Δρ_max = 0.58 e Å⁻³
Δρ_min = −0.35 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/S1600536810015242/lh5024sup1.cif

e-66-o1214-sup1.cif^{(23.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810015242/lh5024Isup2.hkl

e-66-o1214-Isup2.hkl^{(412.1KB, hkl)}

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

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

Cg1 is centroid of the N1/C7/N2/C13/C8 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C12—H12A⋯O1ⁱ	0.93	2.58	3.5007 (13)	173
C20—H20C⋯Cg1	0.96	2.72	3.3432 (13)	123

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Symmetry code: (i) Inline graphic .

Acknowledgments

NA, ASAR and HO are grateful to Universiti Sains Malaysia (USM) for funding the synthetic chemistry work under the USM Research University Grant (1001/PFARMASI/815026). NA thanks USM for the award of a postdoctoral fellowship. HKF and CSY thank USM for the Research University Golden Goose Grant (1001/PFIZIK/811012). CSY also thanks USM for the award of a USM fellowship.

supplementary crystallographic information

Comment

Benzimidazoles are important heterocyclic compounds from the view point of their biological activities. Substituted benzimidazole derivatives have diverse therapeutic applications as they exhibit antiulcerative (Richter, 1997), antioxidant (Can-Eke et al., 1998), anti-HIV-1 (Evans et al., 1997), antiproliferative (Garuti et al., 2000) and antikinase (Sondhi et al., 2005) activities. In view of their importance, the crystal structure determination of the title compound was carried out and the results are presented herein.

The geometric parameters of the title compound (Fig. 1) are comparable to those closely related structures (Arumugam et al., 2010a,b,c). The butyl group is disordered over two positions with refined site-occupancies of 0.883 (3) and 0.117 (3). The dihedral angle between the mean plane of benzimidazole ring system (C7/N1/C8–C13/N2) and the benzene ring (C1–C6) is 39.32 (4)°. The mean plane of carboxylate group (O1/O2/C14–C16) is slightly twisted from the mean plane of benzimidazole ring system with a dihedral angle of 6.87 (5)°. In the crystal structure, the molecules are linked into infinite one-dimensional chains along b axis by intermolecular C12—H12A···O1ⁱ hydrogen bonds (Fig. 2, Table 1). A weak intramolecular C20—H20C···Cg1 interaction may have some influence on the conformation of the molecule (Table 1).

Experimental

The title compound was synthesised using the previous procedures (Arumugam et al., 2010a,b,c) and recrystallized from EtOAc by slow evaporation technique.