Diethyl 4,4′-dihy­droxy-3,3′-{[(3aRS,7aRS)-2,3,3a,4,5,6,7,7a-octa­hydro-1H-1,3-benzimidazole-1,3-di­yl]bis­(methyl­ene)}dibenzoate

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

doi:10.1107/S1600536811039559

. 2011 Oct 5;67(Pt 11):o2817–o2818. doi: 10.1107/S1600536811039559

Diethyl 4,4′-dihydroxy-3,3′-{[(3aRS,7aRS)-2,3,3a,4,5,6,7,7a-octahydro-1H-1,3-benzimidazole-1,3-diyl]bis(methylene)}dibenzoate

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

PMCID: PMC3247559 PMID: 22219864

Abstract

The heterocyclic ring in the title compound, C₂₇H₃₄N₂O₆, has an envelope conformation on one of the bridgehead C atoms [Q(2) = 0.4487 (19) Å and ϕ = 291.3 (2)°]. Two strong intramolecular O—H⋯N hydrogen bonds stabilize the molecular conformation. The benzoate groups differ in the relative orientations of the ethyl groups, as quantified by the values of the C—O—C—C torsion angles of −86.5 (2) and −178.97 (17)°. The carbonyl groups are nearly coplanar with the benzene rings, forming C—C—C—O torsion angles of 0.9 (3) and 3.4 (3)°. The crystal structure is stabilized by weak intermolecular C—H⋯O interactions.

Related literature

For related structures, see: Rivera et al. (2010 ▶, 2011a ▶,b ▶). For the background to this work, see: Van den Enden & Geise (1981 ▶); Geise et al. (1971 ▶). For the synthesis of the precursor, see: Murray-Rust & Riddell (1975 ▶). For puckering parameters, see: Cremer & Pople (1975 ▶). For hydrogen-bond graph-set nomenclature, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₂₇H₃₄N₂O₆
M _r = 482.6
Triclinic,
a = 8.1132 (4) Å
b = 10.9796 (7) Å
c = 15.2450 (8) Å
α = 89.580 (5)°
β = 81.028 (4)°
γ = 70.028 (5)°
V = 1259.19 (13) Å³
Z = 2
Cu Kα radiation
μ = 0.73 mm⁻¹
T = 120 K
0.46 × 0.18 × 0.11 mm

Data collection

Agilent Xcalibur diffractometer with an Atlas (Gemini ultra Cu) detector
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ▶) T _min = 0.752, T _max = 1
11294 measured reflections
4430 independent reflections
3313 reflections with I > 3σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.111
S = 1.64
4430 reflections
323 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.47 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2010 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; 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 datablock(s) global, I. DOI: 10.1107/S1600536811039559/bt5654sup1.cif

e-67-o2817-sup1.cif^{(24.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811039559/bt5654Isup2.hkl

e-67-o2817-Isup2.hkl^{(173.9KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811039559/bt5654Isup3.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
O3—H3o⋯N1	0.89 (3)	1.82 (3)	2.663 (2)	156.9 (19)
O6—H6o⋯N2	0.91 (2)	1.82 (3)	2.669 (2)	154 (3)
C2—H2⋯O1ⁱ	0.96	2.58	3.362 (2)	138
C3—H3⋯O4ⁱⁱ	0.96	2.57	3.436 (2)	151
C8—H8b⋯O1ⁱ	0.96	2.57	3.336 (2)	137
C22—H22⋯O3ⁱⁱⁱ	0.96	2.44	3.351 (2)	159

Open in a new tab

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.

supplementary crystallographic information

Comment

The title compound (I) was obtained from ethyl p-hydroxybenzoate and (2R,7R,11S,16S)-1,8,10,17- tetraazapentacyclo[8.8.1.1^8,17.0^2,7.0^11,16]icosane by a Mannich type reaction as an extension of our work on the structural studies of di-Mannich bases with the 2,3,3a,4,5,6,7,7a-octahydro-1H-1,3-benzimidazole chiral core (Rivera et al., 2010; Rivera et al., 2011a,b).

In the molecule of the title compound (Fig. 1), x-rays analysis indicated that in the cyclohexane ring the C7—C2—C3—C4 endocyclic torsion angle is increased from the normal 55° to 65.6 (2) °. The endocyclic N1—C2—C3—N2 torsion angle in the heterocyclic ring is -45.57 (16) °, which is in the order of the maximum value for torsion angles in five-membered rings (Van den Enden & Geise, 1981). These results confirm the existence of a puckering of the perhydrobenzimidazole moiety, where the 1,2-cyclohexanediamine fragment adopts a chair conformation with shorter endocyclic bond angles [C3—C4—C5, 106.90 (17)°; C2—C7—C6, 106.70 (17)°] and longer bond angles [C4—C5—C6, 112.75 (15); C5—C6—C7; 112.22 (17)°] respect to the normal bond angles [111.4 °. Geise et al., 1971] in a ideal chair conformation. The heterocyclic ring has a envelope conformation on C3 (Q(2) = 0.4487 (19) Å, φ = 291.3 (2)°) (Cremer & Pople, 1975) with endocyclic bond angles between 100.86 (13)° and 106.30 (15)° which are shorter respect the tetrahedrical normal bond angles.

The benzoate moieties differ in the relative orientations of the ethyl groups, Fig. 1, as quantified in the values of the C15—O2—C16—C17 and C25—O5—C26—C27 torsion angles of -86.5 (2) and -178.97 (17)°, respectively, which indicate different orientations with respect to the plane of benzoate moiety. The carbonyl groups are nearly coplanar with the benzene rings forming C10—C11—C15—O1 and C20—C21—C25—O4 torsion angles of 0.9 (3)° and 3.4 (3)° respectively. Bond angles around the carbonyl C atom deviate slightly from 120°. The C—C bond lengths between the atoms in the sequences C9, C10 and C12, C13, [1.385 (2) and 1.382 (2) Å] respectively are similar whereas the C10—C11 [1.400 (3) Å] and C11—C12 [1.392 (3) Å], bond lengths are slightly longer because of the influence of the polar C═O group while the C9—C14 [1.359 (2) Å] is shorter and C13—C14 [1.392 (3) Å] is slightly longer because of the influence of the O—H hydrogen bonded groups.

In the crystal, adjacent molecules are connected via intermolecular C—H···O hydrogen bonds, forming an one-dimensional chain which propagates parallel with the c axis (Fig. 2) where one intermolecular hydrogen-bonding R²₂ (14) (Bernstein et al. 1995) graph-set motifs is generated (Fig 3).

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) prepared previously following described procedures (Murray-Rust & Riddell, 1975), was added dropwise a dioxane solution (3 ml) containing two equivalents of ethyl p-hydroxybenzoate (332 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 18%, m.p. = 408–410 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.

¹H NMR (CDCl₃, 400 MHz): δ 1.28 (4H, m), 1.35 (6H, t, ³J_H,H = 7.2 Hz), 1.86 (2H, m), 2.07 (2H, m), 2.40 (2H, m), 3.56 (2H, d, ²J_H,H = 13.9 Hz, ArCH₂N), 3.56 (2H, s, NCH₂N), 4.20 (2H, d, ²J_H,H = 13.9 Hz, ArCH₂N), 4.30 (4H, q, ³J_H,H = 7.2 Hz), 6.83 (2H, d, ³J_H,H = 8.5 Hz), 7.68 (2H, d, ⁴J_H,H = 2.2 Hz), 7.87 (2H, dd, ³J_H,H = 8.5 Hz, ⁴J_H,H = 2.2 Hz). ¹³C NMR (CDCl₃, 100 MHz): δ 14.4, 23.9, 28.9, 56.0, 60.6, 69.1, 75.6, 116.2, 121.0, 121.8, 130.0, 131.2, 161.8, 166.3.