2-(4-Meth­oxy­benz­yl)-4,6-diphenyl-2,5-diaza­bicyclo­[2.2.2]oct-5-en-3-one

Jo Alen; Liliana Dobrzańska; Luc Van Meervelt; Wim M De Borggraeve

doi:10.1107/S1600536811012165

. 2011 Apr 7;67(Pt 5):o1070–o1071. doi: 10.1107/S1600536811012165

2-(4-Methoxybenzyl)-4,6-diphenyl-2,5-diazabicyclo[2.2.2]oct-5-en-3-one

Jo Alen ^a, Liliana Dobrzańska ^a,^*, Luc Van Meervelt ^b, Wim M De Borggraeve ^a

PMCID: PMC3089292 PMID: 21754395

Abstract

In the crystal structure of the title compound, C₂₆H₂₄N₂O₂, weak intermolecular C—H⋯π interactions involving the benzene of the p-methoxy benzyl group and one of the phenyl rings result in the formation of chains consisting of alternating enantiomers. Weak C—H ⋯O interactions with the methoxy O atom lead to the formation of layers, which are interlinked by further C—H⋯O interactions into a three-dimensional assembly.

Related literature

For our studies on pyrazinone chemistry, see: De Borggraeve et al. (2004 ▶); Azzam et al. (2004 ▶); Alen et al. (2007a ▶); Rombouts et al. (2003 ▶). For a crystal structure with a 2,5-diazabicyclo[2.2.2]oct-5-en-3-one core, see: Rusinov et al. (2009 ▶). For crystal structures with a similar 2,5-diazabicyclo[2.2.2]octane-3,6-dione core, see: Alen et al. (2007b ▶); Holl et al. (2008 ▶).

Experimental

Crystal data

C₂₆H₂₄N₂O₂
M _r = 396.47
Triclinic,
a = 6.2770 (1) Å
b = 11.5684 (2) Å
c = 14.1443 (2) Å
α = 85.497 (1)°
β = 89.900 (1)°
γ = 76.144 (1)°
V = 993.97 (3) Å³
Z = 2
Cu Kα radiation
μ = 0.67 mm⁻¹
T = 100 K
0.34 × 0.18 × 0.15 mm

Data collection

Bruker SMART 6000 diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1997 ▶) T _min = 0.805, T _max = 0.907
10093 measured reflections
3473 independent reflections
2894 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.105
S = 1.05
3473 reflections
272 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2002 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811012165/hg5019sup1.cif

e-67-o1070-sup1.cif^{(23.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811012165/hg5019Isup2.hkl

e-67-o1070-Isup2.hkl^{(170.3KB, hkl)}

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

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

Cg1 and Cg2 are the centroids of the C22–C27 and C9–C14 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C8—H8A⋯Cg2ⁱ	0.99	2.96	3.906 (2)	159
C21—H21A⋯Cg1ⁱⁱ	0.99	2.56	3.411 (2)	144
C19—H19⋯O28ⁱⁱⁱ	0.95	2.51	3.457 (2)	172
C13—H13⋯O30^iv	0.95	2.56	3.368 (2)	143
C29—H29A⋯O30^v	0.98	2.50	3.383 (2)	150

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

Acknowledgments

The authors thank the Fonds Wetenschappelijk Onderzoek – Vlaanderen (FWO) for financial support.

supplementary crystallographic information

Comment

During the course of our studies on 3,5-dichloropyrazinones (Azzam et al., 2004; Alen et al., 2007a) and their conversion to aminopiperidinone carboxylate systems (Rombouts et al., 2003; De Borggraeve et al., 2004), we have isolated the title compound. Although quite a few studies deal with bicyclo[2.2.2]octane systems, only one structure with the 2,5-diazabicyclo[2.2.2]oct-5-en-3-one core (Rusinov et al., 2009) has been reported till now. Quite a few structures contain the similar 2,5-diazabicyclo[2.2.2]octane-3,6-dione core. Of those, two have very close resemblance to the title molecule due to a benzyl substituent on N4. One of those was obtained by us (Alen et al., 2007b) and the other one was published by Wünsch and co-workers (Holl et al., 2008).

The presented structure crystallizes in the triclinic space group P1 with one molecule in the asymmetric unit (Fig. 1). All three aromatic rings participate in weak C—H···π interactions, acting as a donor (C15–C20) or acceptors (C9–C14 and C22–C27). Intramolecular interactions C20—H20···Cg1, (where Cg1 is the centroid of the C22–C27 ring; the C20···Cg1 distance is 3.790 (2) Å, and the C20—H20···Cg1 angle is 149°) influence the orientation of these two rings towards each other. The dihedral angle between their planes is 52.75 (4)°. Rings C9–C14 and C22–C27, with dihedral angles 12.77 (9)° between their corresponding planes and -117.75 (1)° between C9–C4–C21–C22, are involved in weak intermolecular C—H···π interactions. These interactions, namely C8—H8A···Cg2ⁱ (where Cg2 is the centroid of C9–C14, the C8···Cg2 distance is 3.906 (2) Å; symmetry operation (i): -x,1 - y,2 - z) and C21—H21A···Cg1ⁱⁱ (the C21···Cg1 distance is 3.411 (2) Å; symmetry code (ii): 1 - x,1 - y,1 - z), lead to the formation of chains of alternating enantiomers along [-1 0 1] (Fig. 2).These chains are interlinked by C19—H19···O28 interactions to form layers, which are expanded in the third dimension through a number of C—H···O interactions involving O30 (Fig. 3, Table 1).

Experimental

1-(4-methoxybenzyl)-3,5-diphenylpyrazin-2(1H)-one (5 mmol) was dissolved in toluene and heated at 145 °C in a stainless steel bomb under ethene pressure (35 atm) for 4 h. The progress of the Diels-Alder cycloaddition was monitored on TLC, by the disappearance of the starting pyrazinone. After evaporation of the solvent, the crude residue was purified by column chromatography to yield the title compound. Single crystals suitable for X-ray diffraction were obtained by slow evaporation from a chloroform solution.