4,4′-Di-tert-butyl-2,2′-[(3aRS,7aRS)-2,3,3a,4,5,6,7,7a-octa­hydro-1H-1,3-benzimidazole-1,3-di­yl)bis­(methyl­ene)]diphenol

Augusto Rivera; Dency José Pacheco; Jaime Ríos-Motta; Michaela Pojarová; Michal Dušek

doi:10.1107/S1600536811039171

. 2011 Oct 12;67(Pt 11):o2923. doi: 10.1107/S1600536811039171

4,4′-Di-tert-butyl-2,2′-[(3aRS,7aRS)-2,3,3a,4,5,6,7,7a-octahydro-1H-1,3-benzimidazole-1,3-diyl)bis(methylene)]diphenol

Augusto Rivera ^a,^*, Dency José Pacheco ^a, Jaime Ríos-Motta ^a, Michaela Pojarová ^b, Michal Dušek ^b

PMCID: PMC3247337 PMID: 22219955

Abstract

In the title compound, C₂₉H₄₂N₂O₂, the heterocyclic ring has a twist conformation. The cyclohexane ring adopts a chair conformation. The dihedral angle between the aromatic rings is 32.74 (6)°. The molecular conformation is stabilized by two intramolecular O—H⋯N hydrogen bonds with graph-set motif S(6). The crystal packing is stabilized by C—H⋯O and C—H⋯π interactions.

Related literature

For related structures, see: Rivera et al. (2009 ▶, 2010 ▶). For puckering parameters, see: Cremer & Pople (1975 ▶). For hydrogen-bond graph-set nomenclature, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₂₉H₄₂N₂O₂
M _r = 450.65
Triclinic,
a = 6.2383 (2) Å
b = 14.2296 (5) Å
c = 15.6530 (6) Å
α = 105.942 (3)°
β = 95.737 (3)°
γ = 98.041 (3)°
V = 1308.87 (8) Å³
Z = 2
Cu Kα radiation
μ = 0.55 mm⁻¹
T = 120 K
0.22 × 0.10 × 0.08 mm

Data collection

Agilent Xcalibur Atlas Gemini Ultra diffractometer
Absorption correction: analytical (CrysAlis PRO; Agilent, 2011) ▶ T _min = 0.246, T _max = 0.581
28373 measured reflections
4676 independent reflections
3632 reflections with I > 2σ(I)
R _int = 0.139

Refinement

R[F ² > 2σ(F ²)] = 0.054
wR(F ²) = 0.143
S = 1.01
4676 reflections
304 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2011 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811039171/bt5652sup1.cif

e-67-o2923-sup1.cif^{(23.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811039171/bt5652Isup2.hkl

e-67-o2923-Isup2.hkl^{(229KB, hkl)}

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

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

Cg3 and Cg4 are the centroids of the C9–C14 and C20–C25 benzene rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O1⋯N1	0.98	1.77	2.6585 (18)	148
O2—H1O2⋯N2	0.89	1.86	2.6794 (18)	153
C2—H2⋯O2ⁱ	0.98	2.45	3.367 (18)	155
C5—H5B⋯Cg3ⁱⁱ	0.96	2.87	3.625 (2)	135
C19—H19A⋯Cg4ⁱⁱⁱ	0.96	2.84	3.6722 (18)	144

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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 project Praemium Academiae of the Academy of Science of the Czech Republic.

supplementary crystallographic information

Comment

It is known that intramolecular O—H···N hydrogen bonds in Mannich and Schiff bases play a key role in the themodynamic stability of these bases. In our group, research has been focused on the development of novel di-Mannich bases (Rivera et al., 2009, 2010) and their hydrogen-bonded structures. In this work, we report the crystal structure of 4,4'-ditertbutyl-3,3',5,5'-tetramethyl-2,2'-[(3aR,7aR/3aS,7aS)-2,3,3a,4,5,6,7, 7a-octahydro-1H-1,3-benzimidazole-1,3-diyl)bis(methylene)]diphenol (I) as hydrogen bonding model. The molecular structure and atom-numbering scheme for (I) are shown in Fig.1. The bond lengths are normal and comparable to the corresponding values observed in the related structures (Rivera et al., 2009, 2010). The aromatic rings (C9—C14; C20—C25) are essentially planar with the maximum deviation from planarity being 0.0094 (19)° for atom C18.

As with related structures in this series, the heterocyclic ring has a twisted conformation on C2—C7, (Q(2)= 0.4380 (10) Å, φ = 120.3 (2)°, (Cremer & Pople, 1975), and as is typical for such Mannich bases and the molecular conformation is stabilized by two intramolecular O—H···N hydrogen-bond interaction with set graph motif S(6) (Bernstein et al. 1995). However, contrary to other structures, where the difference in the hydrogen bond lengths may be considered to be negligible, the two observed intramolecular hydrogen bond distances were different (Table 1). Considering the similarity of the chemical environment around of both nitrogen atoms, it is then surprising to see the difference in the O—H distances between O2—H2 [O—H = 0.89 Å (2)] and O1—H1 [O—H = 0.98 Å (18)], which is longer compared to the previous compounds (Rivera et al., 2009, 2010). Our observation for this difference can be correlated to the difference in the participation of each one of oxygen atoms in hydrogen-bond networks. Although a hydroxyl group is involved as an acceptor hydrogen bond in an intermolecular hydrogen bond, the other is a non-intermolecular-hydrogen-bonded hydroxyl group. The intermolecular hydrogen bonds [C2—H2A···O2ⁱ, symmetry code: x + 1, y, z] bridge the molecules through head-to-tail into a one-dimensional chain running parallel to the a axis (Figure 2). These chains are stabilized by C—H···π interactions (Table 1).

Experimental

To a dioxane:water (7 ml) solution of the aminal (2R,7R,11S,16S)-1,8,10,17- tetraazapentacyclo[8.8.1.1^8,17.0^2,7.0^11,16]- icosane (276 mg, 1.00 mmol) was added dropwise a dioxane solution (3 ml) containing two equivalents of p-tertbutylphenol (300 mg, 2.00 mmol). The mixture was refluxed for about 10 h. The solvent was evaporated under reduced pressure until a sticky residue appeared. The product was purified by chromatography on a silica column, and subjected to gradient elution with benzene:ethyl acetate (yield 47%, M.p. = 430–431 K). Single crystals of racemic (I) were grown from a chloroform: methanol solution by slow evaporation of the solvent at room temperature over a period of about 2 weeks.