1,4-Dihexyl-1,2,3,4-tetra­hydro­quinoxaline-2,3-dione

El Bourakadi, K.; El Bakri, Y.; Sebhaoui, J.; Rayni, I.; Essassi, E.M.; Mague, J.T.

doi:10.1107/S2414314617010197

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 2| Part 7| July 2017| x171019

https://doi.org/10.1107/S2414314617010197

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1,4-Dihexyl-1,2,3,4-tetrahydroquinoxaline-2,3-dione

Khadija El Bourakadi,^a ^* Youness El Bakri,^a Jihad Sebhaoui,^a Ibtissam Rayni,^a El Mokhtar Essassi ^a and Joel T. Mague ^b

^aLaboratoire de Chimie Organique Hétérocyclique, Centre de Recherche des Sciences des Médicaments, URAC 21, Pôle de Compétence Pharmacochimie, Av Ibn Battouta, BP 1014, Faculté des Sciences, Université Mohammed V, Rabat, Morocco, and ^bDepartment of Chemistry, Tulane University, New Orleans, LA 70118, USA
^*Correspondence e-mail: elbourakadi25@gmail.com

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 3 July 2017; accepted 8 July 2017; online 13 July 2017)

The title compound, C₂₀H₃₀N₂O₂, has crystallographically imposed C₂ symmetry; the hexyl side chain adopts a tttg (t = trans and g = gauche) conformation. In the crystal, C—H⋯O hydrogen bonds link the molecules into chains extending along the b-axis direction. These chains pack to form zigzag sheets lying parallel to (101).

Keywords: crystal structure; quinoxaline; hydrogen bond.

CCDC reference: 1561049

Structure description

This work was carried out in a continuation of our previous work on the synthesis and crystal structures of new quinoxaline-2,3-dione derivatives (Ferfra et al., 2001 ; El Bourakadi et al., 2017a ,b ).

The title molecule (Fig. 1) has crystallographically imposed C₂ rotation symmetry. In the bicyclic unit, the dihedral angle between the two rings is 3.64 (7)°. The n-hexyl side chain adopts a tttg (t = trans and g = gauche) conformation, as indicated by the following torsion angles: N1—C5—C6—C7 = 178.85 (13)°, C5—C6—C7—C8 = −179.63 (15)°, C6—C7—C8—C9 = −179.30 (16)°, and C7—C8—C9—C10 = 70.8 (3)°. In the crystal, molecules form chains extending along the b-axis direction through C1—H1⋯O1 hydrogen bonds (Table 1 and Fig. 2). These chains pack to form zigzag sheets lying parallel to (101), possibly aided by weak C5—H5a⋯π(Cg2) interactions [Cg2 is the centroid of the aromatic ring at (−x + $[{3\over 2}]$ , y − $[{1\over 2}]$ , −z + $[{3\over 2}]$ )], with H⋯Cg = 3.84 Å and C—H⋯Cg = 138° (Fig. 3).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯O1ⁱⁱ	0.93	2.54	3.396 (2)	153
Symmetry code: (ii) x, y+1, z.

Figure 1
The title molecule with the atom-labeling scheme and 50% probability ellipsoids. [Symmetry code: (i) −x + 1, y, −z + $[{3\over 2}]$ .]

Figure 2
Packing viewed towards (101). C—H⋯O hydrogen bonds are depicted by dashed lines.

Figure 3
Packing viewed along the b-axis direction.

Synthesis and crystallization

A mixture of quinoxaline-2,3-dione (1.0 g, 6.17 mmol), potassium carbonate (1.7 g, 12.33 mmol), bromohexane (1.73 ml, 12.33 mmol) and tetra-n-butylammonium bromide as a catalyst in N,N-dimethylformamide (60 ml) was stirred at room temperature for 48 h. After completion of the reaction (monitored by thin-layer chromatography), the solvent was removed under vacuum and the residue was chromatographed on a silica-gel column using hexane and ethyl acetate (80:20 v/v) as eluent. The compound obtained was recrystallzed from ethanol solution to afford the title compound as colourless blocks.

Refinement

Crystal and refinement details are given in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₂₀H₃₀N₂O₂
M_r	330.46
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	295
a, b, c (Å)	13.357 (3), 9.209 (2), 16.743 (4)
β (°)	113.277 (3)
V (Å³)	1891.9 (7)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.08
Crystal size (mm)	0.28 × 0.25 × 0.18

Data collection
Diffractometer	Bruker SMART APEX CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	0.72, 0.99
No. of measured, independent and observed [I > 2σ(I)] reflections	8628, 2323, 1475
R_int	0.040
(sin θ/λ)_max (Å⁻¹)	0.666

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.062, 0.196, 1.04
No. of reflections	2323
No. of parameters	110
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.26, −0.22
Computer programs: APEX3 (Bruker, 2016), SAINT (Bruker, 2016), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), DIAMOND (Brandenburg & Putz, 2012 ) and SHELXTL (Sheldrick, 2008 ).

Structural data

CCDC reference: 1561049

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2414314617010197/hb4157sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617010197/hb4157Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314617010197/hb4157Isup3.cdx

Supporting information file. DOI: https://doi.org/10.1107/S2414314617010197/hb4157Isup4.cml

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: SHELXTL (Bruker, 2016).

1,4-Dihexyl-1,2,3,4-tetrahydroquinoxaline-2,3-dione top

Crystal data top

C₂₀H₃₀N₂O₂	F(000) = 720
M_r = 330.46	D_x = 1.160 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 13.357 (3) Å	Cell parameters from 2136 reflections
b = 9.209 (2) Å	θ = 2.7–27.4°
c = 16.743 (4) Å	µ = 0.08 mm⁻¹
β = 113.277 (3)°	T = 295 K
V = 1891.9 (7) Å³	Block, colourless
Z = 4	0.28 × 0.25 × 0.18 mm

Data collection top

Bruker SMART APEX CCD diffractometer	2323 independent reflections
Radiation source: fine-focus sealed tube	1475 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.040
Detector resolution: 8.3333 pixels mm^-1	θ_max = 28.3°, θ_min = 2.7°
ω scans	h = −17→17
Absorption correction: multi-scan (SADABS; Bruker, 2016)	k = −12→12
T_min = 0.72, T_max = 0.99	l = −21→22
8628 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.062	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.196	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0925P)² + 0.3797P] where P = (F_o² + 2F_c²)/3
2323 reflections	(Δ/σ)_max < 0.001
110 parameters	Δρ_max = 0.26 e Å⁻³
0 restraints	Δρ_min = −0.22 e Å⁻³

Special details top

Experimental. The diffraction data were collected in three sets of 363 frames (0.5° width in ω) at φ = 0, 120 and 240°. A scan time of 60 sec/frame was used.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2sigma(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. H-atoms attached to carbon were placed in calculated positions (C—H = 0.95 - 0.99 Å). All were included as riding contributions with isotropic displacement parameters 1.2 - 1.5 times those of the attached atoms.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.58538 (12)	0.26991 (13)	0.72515 (11)	0.0825 (5)
N1	0.58320 (10)	0.51512 (13)	0.71964 (8)	0.0427 (4)
C1	0.53793 (13)	0.90866 (18)	0.73135 (12)	0.0572 (5)
H1	0.5624	0.9960	0.7177	0.069*
C2	0.57667 (12)	0.77985 (17)	0.71467 (10)	0.0500 (4)
H2	0.6282	0.7807	0.6902	0.060*
C3	0.54071 (10)	0.64763 (15)	0.73341 (9)	0.0387 (4)
C4	0.54659 (13)	0.38519 (17)	0.73476 (11)	0.0523 (4)
C5	0.67419 (13)	0.51352 (18)	0.69052 (11)	0.0485 (4)
H5A	0.7150	0.4241	0.7099	0.058*
H5B	0.7229	0.5937	0.7176	0.058*
C6	0.63673 (13)	0.52534 (19)	0.59270 (11)	0.0515 (4)
H6A	0.5950	0.6139	0.5727	0.062*
H6B	0.5896	0.4439	0.5652	0.062*
C7	0.73340 (14)	0.5263 (2)	0.56635 (11)	0.0561 (5)
H7A	0.7807	0.6071	0.5948	0.067*
H7B	0.7747	0.4375	0.5866	0.067*
C8	0.70034 (17)	0.5390 (2)	0.46884 (13)	0.0676 (6)
H8A	0.6597	0.6283	0.4488	0.081*
H8B	0.6523	0.4589	0.4405	0.081*
C9	0.79629 (19)	0.5382 (3)	0.44171 (14)	0.0778 (6)
H9A	0.7709	0.5675	0.3813	0.093*
H9B	0.8492	0.6095	0.4761	0.093*
C10	0.8516 (3)	0.3937 (3)	0.4521 (2)	0.1177 (10)
H10A	0.7992	0.3214	0.4204	0.177*
H10B	0.8832	0.3679	0.5126	0.177*
H10C	0.9078	0.3991	0.4301	0.177*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.1072 (12)	0.0452 (8)	0.1324 (13)	0.0121 (7)	0.0871 (11)	−0.0001 (7)
N1	0.0406 (7)	0.0436 (7)	0.0549 (8)	0.0030 (5)	0.0307 (6)	0.0019 (5)
C1	0.0525 (10)	0.0403 (9)	0.0791 (12)	−0.0077 (7)	0.0264 (8)	0.0037 (8)
C2	0.0438 (9)	0.0476 (9)	0.0668 (10)	−0.0059 (7)	0.0306 (8)	0.0017 (7)
C3	0.0343 (7)	0.0391 (8)	0.0479 (8)	0.0002 (5)	0.0218 (6)	0.0002 (6)
C4	0.0642 (11)	0.0406 (8)	0.0686 (11)	0.0034 (7)	0.0438 (9)	−0.0002 (7)
C5	0.0396 (8)	0.0610 (10)	0.0558 (10)	0.0072 (7)	0.0306 (7)	0.0027 (7)
C6	0.0446 (9)	0.0628 (10)	0.0552 (10)	0.0012 (7)	0.0282 (7)	−0.0001 (7)
C7	0.0522 (10)	0.0712 (11)	0.0555 (10)	−0.0018 (8)	0.0328 (8)	−0.0013 (8)
C8	0.0656 (12)	0.0890 (14)	0.0603 (11)	−0.0026 (10)	0.0377 (10)	0.0003 (9)
C9	0.0850 (15)	0.0988 (16)	0.0699 (12)	−0.0136 (12)	0.0524 (11)	−0.0046 (10)
C10	0.140 (2)	0.116 (2)	0.145 (2)	0.0097 (19)	0.108 (2)	−0.0140 (18)

Geometric parameters (Å, º) top

O1—C4	1.2195 (18)	C6—H6A	0.9700
N1—C4	1.3537 (19)	C6—H6B	0.9700
N1—C3	1.4027 (17)	C7—C8	1.518 (2)
N1—C5	1.4777 (17)	C7—H7A	0.9700
C1—C2	1.366 (2)	C7—H7B	0.9700
C1—C1ⁱ	1.385 (3)	C8—C9	1.520 (3)
C1—H1	0.9300	C8—H8A	0.9700
C2—C3	1.3895 (19)	C8—H8B	0.9700
C2—H2	0.9300	C9—C10	1.498 (4)
C3—C3ⁱ	1.403 (3)	C9—H9A	0.9700
C4—C4ⁱ	1.520 (3)	C9—H9B	0.9700
C5—C6	1.515 (2)	C10—H10A	0.9600
C5—H5A	0.9700	C10—H10B	0.9600
C5—H5B	0.9700	C10—H10C	0.9600
C6—C7	1.521 (2)

C4—N1—C3	122.59 (12)	H6A—C6—H6B	108.0
C4—N1—C5	117.25 (12)	C8—C7—C6	113.14 (15)
C3—N1—C5	120.12 (11)	C8—C7—H7A	109.0
C2—C1—C1ⁱ	119.73 (9)	C6—C7—H7A	109.0
C2—C1—H1	120.1	C8—C7—H7B	109.0
C1ⁱ—C1—H1	120.1	C6—C7—H7B	109.0
C1—C2—C3	121.46 (14)	H7A—C7—H7B	107.8
C1—C2—H2	119.3	C7—C8—C9	113.57 (17)
C3—C2—H2	119.3	C7—C8—H8A	108.9
C2—C3—N1	121.79 (12)	C9—C8—H8A	108.9
C2—C3—C3ⁱ	118.72 (8)	C7—C8—H8B	108.9
N1—C3—C3ⁱ	119.49 (7)	C9—C8—H8B	108.9
O1—C4—N1	122.75 (15)	H8A—C8—H8B	107.7
O1—C4—C4ⁱ	119.42 (9)	C10—C9—C8	113.86 (19)
N1—C4—C4ⁱ	117.83 (8)	C10—C9—H9A	108.8
N1—C5—C6	113.11 (13)	C8—C9—H9A	108.8
N1—C5—H5A	109.0	C10—C9—H9B	108.8
C6—C5—H5A	109.0	C8—C9—H9B	108.8
N1—C5—H5B	109.0	H9A—C9—H9B	107.7
C6—C5—H5B	109.0	C9—C10—H10A	109.5
H5A—C5—H5B	107.8	C9—C10—H10B	109.5
C5—C6—C7	111.00 (14)	H10A—C10—H10B	109.5
C5—C6—H6A	109.4	C9—C10—H10C	109.5
C7—C6—H6A	109.4	H10A—C10—H10C	109.5
C5—C6—H6B	109.4	H10B—C10—H10C	109.5
C7—C6—H6B	109.4

C1ⁱ—C1—C2—C3	0.7 (3)	C3—N1—C4—C4ⁱ	1.9 (3)
C1—C2—C3—N1	−177.46 (15)	C5—N1—C4—C4ⁱ	179.67 (16)
C1—C2—C3—C3ⁱ	2.9 (3)	C4—N1—C5—C6	96.77 (17)
C4—N1—C3—C2	−177.72 (14)	C3—N1—C5—C6	−85.38 (17)
C5—N1—C3—C2	4.5 (2)	N1—C5—C6—C7	178.85 (13)
C4—N1—C3—C3ⁱ	2.0 (3)	C5—C6—C7—C8	−179.63 (15)
C5—N1—C3—C3ⁱ	−175.77 (15)	C6—C7—C8—C9	−179.30 (16)
C3—N1—C4—O1	−177.92 (16)	C7—C8—C9—C10	70.8 (3)
C5—N1—C4—O1	−0.1 (3)

Symmetry code: (i) −x+1, y, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···O1ⁱⁱ	0.93	2.54	3.396 (2)	153

Symmetry code: (ii) x, y+1, z.

References

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