1,3-Dibenzyl-1H-anthra[1,2-d]imidazole-2,6,11(3H)-trione

Zahra Afrakssou; Youssef Kandri Rodi; Frédéric Capet; El Mokhtar Essassi; Lahcen El Ammari

doi:10.1107/S1600536811015078

. 2011 Apr 29;67(Pt 5):o1253–o1254. doi: 10.1107/S1600536811015078

1,3-Dibenzyl-1H-anthra[1,2-d]imidazole-2,6,11(3H)-trione

Zahra Afrakssou ^a, Youssef Kandri Rodi ^a,^*, Frédéric Capet ^b, El Mokhtar Essassi ^c, Lahcen El Ammari ^d

PMCID: PMC3089129 PMID: 21754544

Abstract

The molecule of the title compound, C₂₉H₂₀N₂O₃, contains four fused rings, three are six-membered rings and one is the five-membered imidazole ring. The fused-ring system is linked to two benzyl groups. The four fused rings are folded around the O=C⋯C=O direction of the anthraquinone, with a dihedral angle of 16.36 (8)° between the two terminal rings (A and D). The imidazole ring (D) is almost perpendicular to the two benzyl groups (E and F) with dihedral angles of 86.69 (17) and 83.15 (13)°, respectively. In the crystal, adjacent molecules are linked by intermolecular C—H⋯O hydrogen bonding.

Related literature

For background to the pharmacological activity of anthraquinone, see: Alves et al. (2004 ▶); Gatto et al. (1996 ▶); Krapcho et al. (1991 ▶). For information on its use as a synthetic dye, see: Naeimi & Namdari (2009 ▶). For related structures, see: Afrakssou et al. (2010 ▶); Guimarães et al. (2009 ▶). For puckering parameters, see: Cremer & Pople (1975 ▶).

Experimental

Crystal data

C₂₉H₂₀N₂O₃
M _r = 444.47
Orthorhombic,
a = 8.1389 (3) Å
b = 12.8748 (4) Å
c = 21.5528 (8) Å
V = 2258.45 (14) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 296 K
0.49 × 0.18 × 0.15 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.982, T _max = 0.987
36228 measured reflections
2629 independent reflections
2137 reflections with I > 2σ(I)
R _int = 0.047

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.108
S = 1.05
2629 reflections
308 parameters
H-atom parameters constrained
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT-Plus (Bruker, 2009 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▶) and ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811015078/dn2679sup1.cif

e-67-o1253-sup1.cif^{(20.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811015078/dn2679Isup2.hkl

e-67-o1253-Isup2.hkl^{(126.5KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811015078/dn2679Isup3.cml

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C13—H13⋯O1ⁱ	0.93	2.39	3.312 (3)	171
C23—H23A⋯O2ⁱⁱ	0.97	2.47	3.439 (4)	174

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) .

supplementary crystallographic information

Comment

Anthraquinone-containing extracts from different plant sources such as senna, cascara, aloe, frangula, and rhubarb have been found to have wide variety of pharmacological activities such as antiinflammatory, wound healing, analgesic, antipyretic, antimicrobial, and antitumor activities (Alves et al., 2004). Anthraquinone planarity allows an intercalation between base pairs of DNA in the β conformation, while its redox properties are linked to the production of radical species in biological systems. The chemical and biological activity of anthraquinone compounds depends on the different substituents of the planar ring system (Gatto et al., 1996; Krapcho et al., 1991). Anthraquinone dyes are used for coloration of cotton and cellulose fibers as well as of hydrophobic, synthetic materials (Naeimi et al., 2009).

The present work is a continuation of the preparation of new derivatives of anthra[1,2-d]imidazole-2,6,11–trione for biological applications (Afrakssou et al., (2010), Guimarães et al. (2009)). The reactivity of benzyl bromide towards 1H-anthra [2,1-d]imidazole-2,6,11(3H)-trione under phase-transfer catalysis conditions using tetra n-butyl ammonium bromide (TBAB) as catalyst and potassium carbonate as base leads to 1,3-dibenzyl-1H-anthra[2,1-d]imidazole-2,6,11(3H)-trione with good yield (Scheme 1).

All rings forming the molecule are planar except for the anthraquinone (B) which adopts a twisted conformation (Fig. 1), as indicated by Cremer & Pople (1975) with puckering parameters Q = 0.242 (2) Å, θ = 104.7 (5) ° and φ = 137.6 (5)°. The fused five and six-membered rings (C, D) are planar and built with A ring (sheme 1) a dihedral angle of 16.36 (8) °. The imidazole ring (D) is almost perpendicular to the two benzyl groups (E, F) with dihedral angles of 86.69 (17) ° and 83.15 (13) ° respectively. In the crystal, adjacent molecules are linked by intermolecular C—H···O hydrogen bonding (Table 1). The structure is further stabilized by π-π interactions between rings A and D with a centroid to centroid distance of 3.411 (2) Å and an interplanar distance of 3.395 (2)Å resulting in slight offset of 5.32°.

Experimental

To a solution of 1H-anthra [2, 1 - d] imidazole-2, 6, 11(3H)-trione (0.5 g, 0.18 mmol), potassium carbonate (0.78 g, 0.56 mmol) and tetra n-butylammonium bromide (0.06 g, 0.018 mmol) in DMF (15 ml)) was added Benzyl bromide (0.56 ml, 0.47 mmol). Stirring was continued at room temperature for 24 h. The mixture was filtered and the solvent removed. The residue was extracted with water. The organic compound was chromatographed on a column of silica gel with ethyl acetate-hexane (1/1) as eluent. Orange crystals were isolated when the solvent was allowed to evaporate.