4,4′-Dibromo-2,2′-{[(3aS,7aS)-2,3,3a,4,5,6,7,7a-octa­hydro-1H-1,3-benzimidazole-1,3-di­yl]bis­(methyl­idene)}diphenol

Augusto Rivera; Diego Quiroga; Jaime Ríos-Motta; Michal Dušek; Karla Fejfarová

doi:10.1107/S1600536811006489

. 2011 Mar 2;67(Pt 4):o753. doi: 10.1107/S1600536811006489

4,4′-Dibromo-2,2′-{[(3aS,7aS)-2,3,3a,4,5,6,7,7a-octahydro-1H-1,3-benzimidazole-1,3-diyl]bis(methylidene)}diphenol

Augusto Rivera ^a,^*, Diego Quiroga ^a, Jaime Ríos-Motta ^a, Michal Dušek ^b, Karla Fejfarová ^b

PMCID: PMC3099886 PMID: 21754050

Abstract

The cyclohexane ring in the title compound, C₂₁H₂₄Br₂N₂O₂, adopts a chair conformation and the five-membered ring to which it is fused has a twisted envelope conformation. The asymmetric unit contains one half-molecule, which is related to the other half by a twofold rotation axis. The two N atoms of the five-membered ring are linked to the hydroxy groups by intramolecular O—H⋯N hydrogen bonds. In the crystal, intermolecular C—H⋯O and C—H⋯π interactions occur.

Related literature

For a related structure, see: Rivera et al. (2010 ▶). For uses of di-Mannich bases, see: Mitra et al. (2006 ▶).

Experimental

Crystal data

C₂₁H₂₄Br₂N₂O₂
M _r = 496.2
Orthorhombic,
a = 5.9645 (2) Å
b = 18.5497 (4) Å
c = 9.0494 (2) Å
V = 1001.22 (5) Å³
Z = 2
Cu Kα radiation
μ = 5.32 mm⁻¹
T = 120 K
0.19 × 0.13 × 0.10 mm

Data collection

Oxford Diffraction Xcalibur diffractometer with an Atlas detector
Absorption correction: analytical (CrysAlis PRO; Oxford Diffraction, 2009 ▶) T _min = 0.454, T _max = 0.678
17493 measured reflections
1749 independent reflections
1739 reflections with I > 3σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.015
wR(F ²) = 0.049
S = 1.21
1749 reflections
126 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.11 e Å⁻³
Δρ_min = −0.12 e Å⁻³
Absolute structure: Flack (1983 ▶), 670 Friedel pairs
Flack parameter: 0.008 (20)

Data collection: CrysAlis CCD (Oxford Diffraction, 2009 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2009 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SIR2002 (Burla et al., 2003 ▶); program(s) used to refine structure: JANA2006 (Petříček et al., 2006 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: JANA2006.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811006489/ng5118sup1.cif

e-67-0o753-sup1.cif^{(17.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811006489/ng5118Isup2.hkl

e-67-0o753-Isup2.hkl^{(86.3KB, hkl)}

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

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

Cg2 is the centroid of the C3–C8 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1o⋯N1	0.833 (19)	1.905 (18)	2.6506 (13)	148.3 (19)
C1—H1a⋯O1ⁱ	0.96	2.57	3.3351 (11)	137
C8—H8⋯Cg2ⁱⁱ	0.96	2.85	3.5407 (16)	130
C11—H11b⋯Cg2ⁱⁱⁱ	0.96	2.86	3.728 (2)	150

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

Acknowledgments

We acknowledge the Dirección de Investigaciones, Sede Bogotá (DIB) de La Universidad Nacional de Colombia, for financial support of this work, as well as the Institutional Research Plan No. AVOZ10100521 of the Institute of Physics and the Praemium Academiae Project of the Academy of Sciences of the Czech Republic. DQ acknowledges the Vicerrectoría Académica de la Universidad Nacional de Colombia for a fellowship.

supplementary crystallographic information

Comment

The title compound was obtained by reaction of racemic cyclic aminal (2R,7R,11S,16S)-1,8,10,17-tetraazapentacyclo[8.8.1.1^8,17.0^2,7.0^11,16]icosane with p-bromophenol. The molecular structure and atom-numbering scheme for (I) are shown in Fig. 1. Selected angles and bond lengths are listed in Table 1. Its X-ray structure confirms the presence of intramolecular hydrogen bonds between the phenolic hydroxyl groups and nitrogen atoms [N—H, 1.903 (18) Å] that is however by 0.13 Å longer in comparison with related structure (Rivera et al., 2010), whereas the N···O distance [2.6506 (14) Å] is in good agreement with the one found in related structure [2.652 (2) Å]. Similar to this related structure, the observed C—O bond length [1.353 (2) Å] is considerably shortened in relation to other Mannich bases.

In the title compound, C₂₁H₂₄Br₂N₂O₂, the asymmetric unit contains one-half of the molecule, which is related to the other half by a twofold rotation axis [symmetry code: - x, y, -z] passing through C1. The orthorhombic unit cell contains two molecules. Instead, the molecules have identical (S,S)-molecular configuration and its absolute structure was determined with a Flack parameter of 0.01 (2) (Flack, 1983).

Experimental

Physical Measurements

The melting point was determined with an Electrothermal apparatus, and it has not been corrected. IR spectrum was recorded as KBr pellets at 292 K on a Perkin-Elmer Paragon FT—IR instrument. NMR spectra were performed in CDCl₃ at room temperature on a Bruker AMX 400 Advance spectrometer.

Preparation of 4,4'-Dibromo-2,2'-(3aS,7aS)-2,3,3a,4,5,6,7,7a-octahydro-1H-1,3- benzimidazole-1,3-diyl)bis(methylene)]diphenol) (I)

A solution of (2R,7R,11S,16S)-1,8,10,17-tetraazapentacyclo[8.8.1.^18,17.0^2,7.0^11,16]icosane (3) (276 mg, 1.00 mmol) in dioxane (3 ml) and water (4 ml), prepared beforehand following previously described procedures, was added dropwise in a dioxane solution (3 ml) containing two equivalents of p-bromophenol (346 mg, 2.00 mmol) in a two-necked round-bottomed flask. The mixture was refluxed for about 6 h until precipitation of a colourless solid. The resulting solid was collected by filtration, washed with cool methanol and dried under vacuum (yield 47%, m.p. = 497–499 K). Next, the crude product (100 mg, 0.202 mmol) was dissolved in 5 ml of a 4:1 mixture of chloroform: methanol. Single crystals of title compound (I) suitable for X-ray analysis were grown by slow evaporation of the solvent at room temperature over a period of about 2 weeks in a preferential crystallization (yield 35%). ¹H NMR (CDCl₃, 400 MHz): δ 1.27 (4H, m), 1.85 (2H, m), 2.05 (2H, m), 2.33 (2H, m), 3.41 (2H, d, J = 14.0 Hz, ArCH₂N), 3.51 (2H, s, NCH₂N), 4.14 (2H, d, J = 14.0 Hz, ArCH₂N), 6.69 (2H, d, J = 8.8 Hz), 7.06 (2H, s), 7.24 (2H, d, J = 8.8 Hz). ¹³C NMR (CDCl₃, 100 MHz): δ 23.9, 28.9, 55.8, 69.1, 75.7, 111.1, 118.1, 123.4, 130.6, 131.8, 156.6.