2,3-Bis(4-ethoxy­phen­yl)quinoxaline

Ye, P.-P.; Zhang, C.-L.; Du, Z.-Q.

doi:10.1107/S1600536809052295

organic compounds

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ISSN: 2056-9890

Volume 66| Part 1| January 2010| Page o130

doi:10.1107/S1600536809052295

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2,3-Bis(4-ethoxyphenyl)quinoxaline

Ping-Ping Ye,^a Cai-Li Zhang ^a and Zhi-Qiang Du ^a ^*

^aDepartment of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
^*Correspondence e-mail: duzq@zju.edu.cn

(Received 12 November 2009; accepted 5 December 2009; online 12 December 2009)

The title compound, C₂₄H₂₂N₂O₂, was prepared by condensation of 1,2-bis(4-ethoxyphenyl)ethane-1,2-dione and 1,2-diaminobenzene. The asymmetric unit contains one half-molecule, close to a twofold axis. The plane of the quinoxaline ring is twisted with respect to the planes of the two ethoxyphenyl ring systems, exhibiting dihedral angles of 39.95 (9)°. The crystal packing is dominated by weak C—H⋯π interactions. No classical hydrogen bonds or stacking interactions are observed.

Related literature

For applications of quinoxaline derivatives, see: Seitz et al. (2002 ); He et al. (2003 ); Dailey et al. (2001 ). For the syntheses of quinoxaline derivatives, see: Bhosale et al. (2005 ); More et al. (2006 ); Raw et al. (2003 ). For the synthesis of the title compound, see: Heravi et al. (2006 ).

Experimental

Crystal data

C₂₄H₂₂N₂O₂
M_r = 370.44
Monoclinic, C 2/c
a = 19.4837 (18) Å
b = 11.2682 (11) Å
c = 9.2629 (9) Å
β = 100.196 (1)°
V = 2001.5 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 K
0.37 × 0.27 × 0.24 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.972, T_max = 0.981
6487 measured reflections
1743 independent reflections
1560 reflections with I > 2σ(I)
R_int = 0.028

Refinement

R[F² > 2σ(F²)] = 0.035
wR(F²) = 0.092
S = 1.03
1743 reflections
128 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.12 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C10—H10⋯Cg1ⁱ	0.93	2.85	3.3936 (17)	119
C11—H11A⋯Cg2ⁱⁱ	0.96	2.93	3.743 (2)	143
Symmetry codes: (i) -x+1, -y, -z; (ii) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z]$ . Cg1 is the centroid of the N1,C1,C1′,N1′,C2 ring and Cg2 is the centroid of the C5–C10 ring.

Data collection: SMART (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXL97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809052295/bh2259sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809052295/bh2259Isup2.hkl

checkCIF report

Comment top

Quinoxaline derivatives are an important class of benzoheterocycles. They have found applications as anticancer, antiviral, and antibacterial agents (Seitz et al., 2002; He et al., 2003), and dyes (Dailey et al., 2001). In recent years, many synthesis of quinoxaline derivatives have been reported (Raw et al., 2003; Bhosale et al., 2005; More et al., 2006). The title compound is one of such quinoxaline derivatives. We have synthesized the title compound and report now its crystal structure.

The molecular structure of title compound is as shown in Fig. 1. The molecule lies on a twofold axis. The quinoxaline ring and two ethoxyphenyl rings are independent and planar. The quinoxaline ring is twisted with respect to the ethoxyphenyl ring with a dihedral angle of 39.95 (9)°. Packing is dominated by rather weak C—H···π interactions (Table 1). In contrast, no significant hydrogen bonds or stacking interactions are observed in the crystal structure.

Related literature top

For applications of quinoxaline derivatives, see: Seitz et al. (2002); He et al. (2003); Dailey et al. (2001). For the syntheses of quinoxaline derivatives, see:

Bhosale et al. (2005); More et al. (2006); Raw et al. (2003). For the synthesis of the title compound, see: Heravi et al. (2006).

Experimental top

The title compound was prepared according to the procedure reported by Heravi et al. (2006). A mixture of 1,2-bis(4-ethoxyphenyl)ethane-1,2-dione (1 mmol), 1,2-diaminobenzene (1 mmol), and ammonium fluoride (10% mol) in CH₃OH (5 ml) was stirred at room temperature. The progress of the reaction was monitored by TLC. After completion, CH₂Cl₂ was added to the reaction mixture. The product dissolves in CH₂Cl₂ and the catalyst separated easily from the mixture by filtration. Solvents evaporation afforded the crude product. The solid was recrystallized from ethanol. Single crystals suitable for X-ray data collection were obtained by recrystallization from a dichloromethane-methanol mixture.

Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXL97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

Fig. 1. The molecular structure of the title molecule, with 40% probability displacement ellipsoids. Atoms labeled with _2 are generated by symmetry 1 - x, y, 1/2 - z.

2,3-Bis(4-ethoxyphenyl)quinoxaline top

Crystal data top

C₂₄H₂₂N₂O₂	F(000) = 784
M_r = 370.44	D_x = 1.229 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 3608 reflections
a = 19.4837 (18) Å	θ = 5.6–52.7°
b = 11.2682 (11) Å	µ = 0.08 mm⁻¹
c = 9.2629 (9) Å	T = 293 K
β = 100.196 (1)°	Prism, yellow
V = 2001.5 (3) Å³	0.37 × 0.27 × 0.24 mm
Z = 4

Data collection top

Bruker SMART CCD area-detector diffractometer	1743 independent reflections
Radiation source: fine-focus sealed tube	1560 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.028
ϕ and ω scans	θ_max = 25.0°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −23→22
T_min = 0.972, T_max = 0.981	k = −12→13
6487 measured reflections	l = −10→10

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.035	H-atom parameters constrained
wR(F²) = 0.092	w = 1/[σ²(F_o²) + (0.0422P)² + 0.9006P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max < 0.001
1743 reflections	Δρ_max = 0.17 e Å⁻³
128 parameters	Δρ_min = −0.12 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0289 (19)

Crystal data top

C₂₄H₂₂N₂O₂	V = 2001.5 (3) Å³
M_r = 370.44	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 19.4837 (18) Å	µ = 0.08 mm⁻¹
b = 11.2682 (11) Å	T = 293 K
c = 9.2629 (9) Å	0.37 × 0.27 × 0.24 mm
β = 100.196 (1)°

Data collection top

Bruker SMART CCD area-detector diffractometer	1743 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1560 reflections with I > 2σ(I)
T_min = 0.972, T_max = 0.981	R_int = 0.028
6487 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.035	0 restraints
wR(F²) = 0.092	H-atom parameters constrained
S = 1.03	Δρ_max = 0.17 e Å⁻³
1743 reflections	Δρ_min = −0.12 e Å⁻³
128 parameters

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

	x	y	z	U_iso*/U_eq
C1	0.46773 (6)	−0.00154 (10)	0.19704 (12)	0.0281 (3)
N1	0.43983 (5)	−0.10164 (8)	0.14060 (11)	0.0321 (3)
C2	0.47078 (6)	−0.20565 (10)	0.19257 (13)	0.0333 (3)
C3	0.44262 (8)	−0.31482 (11)	0.13548 (16)	0.0459 (4)
H3	0.4044	−0.3157	0.0594	0.055*
C4	0.47143 (9)	−0.41910 (12)	0.19182 (17)	0.0580 (4)
H4	0.4531	−0.4908	0.1529	0.070*
O1	0.31520 (5)	0.41927 (8)	0.03771 (11)	0.0503 (3)
C8	0.35080 (6)	0.31489 (10)	0.06662 (14)	0.0369 (3)
C6	0.41928 (6)	0.19601 (11)	0.25439 (13)	0.0365 (3)
H6	0.4395	0.1856	0.3523	0.044*
C10	0.39626 (6)	0.12701 (10)	0.00690 (13)	0.0334 (3)
H10	0.4003	0.0690	−0.0625	0.040*
C5	0.42812 (6)	0.10907 (10)	0.15155 (12)	0.0294 (3)
C7	0.38108 (7)	0.29661 (11)	0.21256 (14)	0.0402 (3)
H7	0.3754	0.3532	0.2826	0.048*
C9	0.35851 (6)	0.22927 (11)	−0.03675 (14)	0.0368 (3)
H9	0.3385	0.2403	−0.1347	0.044*
C11	0.28097 (7)	0.44243 (12)	−0.10928 (17)	0.0514 (4)
H11A	0.2476	0.3801	−0.1428	0.062*
H11B	0.3148	0.4455	−0.1745	0.062*
C12	0.24435 (8)	0.55950 (14)	−0.1089 (2)	0.0689 (5)
H12A	0.2209	0.5777	−0.2065	0.103*
H12B	0.2778	0.6204	−0.0755	0.103*
H12C	0.2109	0.5552	−0.0445	0.103*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0309 (6)	0.0289 (6)	0.0251 (6)	−0.0019 (5)	0.0067 (5)	0.0001 (4)
N1	0.0342 (5)	0.0298 (6)	0.0320 (6)	−0.0025 (4)	0.0051 (4)	−0.0004 (4)
C2	0.0394 (6)	0.0289 (6)	0.0328 (7)	−0.0020 (5)	0.0096 (5)	−0.0004 (5)
C3	0.0582 (8)	0.0346 (7)	0.0437 (8)	−0.0107 (6)	0.0053 (6)	−0.0041 (6)
C4	0.0851 (12)	0.0279 (7)	0.0607 (10)	−0.0092 (7)	0.0119 (8)	−0.0052 (6)
O1	0.0515 (6)	0.0377 (5)	0.0575 (6)	0.0140 (4)	−0.0017 (5)	0.0093 (4)
C8	0.0338 (6)	0.0303 (7)	0.0451 (8)	0.0029 (5)	0.0032 (5)	0.0078 (5)
C6	0.0426 (7)	0.0371 (7)	0.0286 (6)	0.0073 (5)	0.0030 (5)	0.0014 (5)
C10	0.0343 (6)	0.0331 (7)	0.0320 (7)	−0.0020 (5)	0.0037 (5)	−0.0010 (5)
C5	0.0285 (5)	0.0290 (6)	0.0307 (6)	−0.0010 (5)	0.0048 (4)	0.0015 (5)
C7	0.0472 (7)	0.0345 (7)	0.0383 (7)	0.0093 (6)	0.0061 (6)	−0.0027 (5)
C9	0.0365 (6)	0.0385 (7)	0.0327 (7)	−0.0014 (5)	−0.0015 (5)	0.0065 (5)
C11	0.0398 (7)	0.0482 (8)	0.0622 (10)	0.0006 (6)	−0.0024 (6)	0.0242 (7)
C12	0.0434 (8)	0.0553 (10)	0.1049 (14)	0.0103 (7)	0.0049 (8)	0.0361 (9)

Geometric parameters (Å, º) top

C1—N1	1.3193 (14)	C6—C7	1.3737 (17)
C1—C1ⁱ	1.452 (2)	C6—C5	1.3981 (16)
C1—C5	1.4871 (15)	C6—H6	0.9300
N1—C2	1.3660 (15)	C10—C9	1.3881 (17)
C2—C3	1.4111 (17)	C10—C5	1.3882 (16)
C2—C2ⁱ	1.414 (2)	C10—H10	0.9300
C3—C4	1.3655 (19)	C7—H7	0.9300
C3—H3	0.9300	C9—H9	0.9300
C4—C4ⁱ	1.406 (3)	C11—C12	1.500 (2)
C4—H4	0.9300	C11—H11A	0.9700
O1—C8	1.3676 (14)	C11—H11B	0.9700
O1—C11	1.4301 (17)	C12—H12A	0.9600
C8—C9	1.3860 (18)	C12—H12B	0.9600
C8—C7	1.3912 (18)	C12—H12C	0.9600

N1—C1—C1ⁱ	120.98 (6)	C5—C10—H10	119.2
N1—C1—C5	116.59 (10)	C10—C5—C6	117.88 (11)
C1ⁱ—C1—C5	122.38 (6)	C10—C5—C1	121.10 (10)
C1—N1—C2	117.95 (10)	C6—C5—C1	120.97 (10)
N1—C2—C3	119.85 (11)	C6—C7—C8	120.77 (11)
N1—C2—C2ⁱ	120.77 (6)	C6—C7—H7	119.6
C3—C2—C2ⁱ	119.33 (8)	C8—C7—H7	119.6
C4—C3—C2	120.05 (13)	C8—C9—C10	119.56 (11)
C4—C3—H3	120.0	C8—C9—H9	120.2
C2—C3—H3	120.0	C10—C9—H9	120.2
C3—C4—C4ⁱ	120.61 (8)	O1—C11—C12	107.47 (14)
C3—C4—H4	119.7	O1—C11—H11A	110.2
C4ⁱ—C4—H4	119.7	C12—C11—H11A	110.2
C8—O1—C11	118.57 (11)	O1—C11—H11B	110.2
O1—C8—C9	125.21 (11)	C12—C11—H11B	110.2
O1—C8—C7	115.51 (11)	H11A—C11—H11B	108.5
C9—C8—C7	119.28 (11)	C11—C12—H12A	109.5
C7—C6—C5	120.80 (11)	C11—C12—H12B	109.5
C7—C6—H6	119.6	H12A—C12—H12B	109.5
C5—C6—H6	119.6	C11—C12—H12C	109.5
C9—C10—C5	121.69 (11)	H12A—C12—H12C	109.5
C9—C10—H10	119.2	H12B—C12—H12C	109.5

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the N1,C1,C1',N1',C2 ring and Cg2 is the centroid of the C5–C10 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C10—H10···Cg1ⁱⁱ	0.93	2.85	3.3936 (17)	119
C11—H11A···Cg2ⁱⁱⁱ	0.96	2.93	3.743 (2)	143

Symmetry codes: (ii) −x+1, −y, −z; (iii) −x+1/2, −y+1/2, −z.

Experimental details

Crystal data
Chemical formula	C₂₄H₂₂N₂O₂
M_r	370.44
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	293
a, b, c (Å)	19.4837 (18), 11.2682 (11), 9.2629 (9)
β (°)	100.196 (1)
V (Å³)	2001.5 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.37 × 0.27 × 0.24

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.972, 0.981
No. of measured, independent and observed [I > 2σ(I)] reflections	6487, 1743, 1560
R_int	0.028
(sin θ/λ)_max (Å⁻¹)	0.594

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.035, 0.092, 1.03
No. of reflections	1743
No. of parameters	128
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.17, −0.12

Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the N1,C1,C1',N1',C2 ring and Cg2 is the centroid of the C5–C10 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C10—H10···Cg1ⁱ	0.93	2.85	3.3936 (17)	119
C11—H11A···Cg2ⁱⁱ	0.96	2.93	3.743 (2)	143

Symmetry codes: (i) −x+1, −y, −z; (ii) −x+1/2, −y+1/2, −z.

Acknowledgements

The authors thank the National Natural Science Foundation of China (grant No. 20376071).

References

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