(4aR*,8aS*)-2,3-Diphenyl-4a,5,6,7,8,8a-hexa-hydro-quinoxaline.

In the title compound, C(20)H(20)N(2), the quinoxaline ring adopts a very distorted half-chair conformation [N=C-C=N = 22.7 (2)° for the nominally coplanar atoms] and the cyclo-hexane ring adopts a chair conformation. The quinoxaline and cyclo-hexane rings are cis-fused. The two phenyl rings form a dihedral angle of 63.88 (7)°.

Related literature

For background to dihydro­pyrazine derivatives, see: Raw et al. (2003 ▶). For related structures, see: Reich et al. (2004 ▶); Wang et al. (2008) ▶.

Experimental

Crystal data

C20H20N2

M = 288.38

Orthorhombic,

a = 6.3546 (1) Å

b = 13.4894 (2) Å

c = 19.1921 (3) Å

V = 1645.14 (4) Å3

Z = 4

Cu Kα radiation

μ = 0.52 mm−1

T = 293 K

0.20 × 0.20 × 0.10 mm

Data collection

Bruker SMART APEX CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2004) ▶ T min = 0.902, T max = 0.949

4074 measured reflections

2739 independent reflections

2703 reflections with I > 2σ(I)

R int = 0.010

Refinement

R[F 2 > 2σ(F 2)] = 0.036

wR(F 2) = 0.099

S = 1.05

2739 reflections

199 parameters

H-atom parameters constrained

Δρmax = 0.14 e Å−3

Δρmin = −0.14 e Å−3

Data collection: APEX2 (Bruker, 2004) ▶; cell refinement: SAINT-Plus (Bruker, 2001) ▶; data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812028061/hb6855sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812028061/hb6855Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536812028061/hb6855Isup3.cml

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

C20H20N2	F(000) = 616
Mr = 288.38	Dx = 1.164 Mg m−3
Orthorhombic, P212121	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2779 reflections
a = 6.3546 (1) Å	θ = 3.3–72.4°
b = 13.4894 (2) Å	µ = 0.52 mm−1
c = 19.1921 (3) Å	T = 293 K
V = 1645.14 (4) Å3	Block, yellow
Z = 4	0.20 × 0.20 × 0.10 mm

Bruker SMART APEX CCD diffractometer	2739 independent reflections
Radiation source: fine-focus sealed tube	2703 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.010
phi and ω scans	θmax = 72.6°, θmin = 5.7°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −7→5
Tmin = 0.902, Tmax = 0.949	k = −15→16
4074 measured reflections	l = −17→23

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.036	H-atom parameters constrained
wR(F2) = 0.099	w = 1/[σ2(Fo2) + (0.0617P)2 + 0.1364P] where P = (Fo2 + 2Fc2)/3
S = 1.05	(Δ/σ)max < 0.001
2739 reflections	Δρmax = 0.14 e Å−3
199 parameters	Δρmin = −0.14 e Å−3
0 restraints	Absolute structure: unk
Primary atom site location: structure-invariant direct methods

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

	x	y	z	Uiso*/Ueq
N1	0.18801 (18)	0.39372 (8)	0.62663 (6)	0.0410 (3)
N2	−0.0579 (2)	0.33893 (9)	0.50829 (6)	0.0492 (3)
C1	0.1165 (2)	0.29069 (10)	0.61739 (7)	0.0419 (3)
H1B	0.2255	0.2542	0.5920	0.050*
C2	0.0862 (3)	0.24167 (12)	0.68822 (8)	0.0544 (4)
H2B	0.0632	0.1712	0.6818	0.065*
H2C	0.2128	0.2501	0.7158	0.065*
C3	−0.0991 (3)	0.28592 (15)	0.72680 (8)	0.0654 (5)
H3A	−0.0700	0.3549	0.7372	0.079*
H3B	−0.1183	0.2512	0.7706	0.079*
C4	−0.2993 (3)	0.27893 (16)	0.68428 (11)	0.0674 (5)
H4A	−0.4138	0.3100	0.7096	0.081*
H4B	−0.3353	0.2098	0.6772	0.081*
C5	−0.2729 (2)	0.32958 (14)	0.61387 (10)	0.0605 (4)
H5A	−0.3992	0.3200	0.5863	0.073*
H5B	−0.2536	0.4002	0.6208	0.073*
C6	−0.0850 (2)	0.28777 (10)	0.57496 (7)	0.0453 (3)
H6A	−0.1155	0.2181	0.5647	0.054*
C7	0.1606 (2)	0.45124 (10)	0.57517 (7)	0.0388 (3)
C8	0.0606 (2)	0.41514 (9)	0.50853 (7)	0.0414 (3)
C9	0.2231 (3)	0.55791 (10)	0.58259 (7)	0.0442 (3)
C10	0.4058 (3)	0.58177 (13)	0.61799 (9)	0.0591 (4)
H10A	0.4885	0.5318	0.6371	0.071*
C11	0.4658 (4)	0.68056 (16)	0.62502 (11)	0.0769 (6)
H11A	0.5903	0.6965	0.6479	0.092*
C12	0.3419 (5)	0.75417 (13)	0.59834 (10)	0.0843 (8)
H12A	0.3823	0.8201	0.6031	0.101*
C13	0.1589 (5)	0.73123 (13)	0.56464 (10)	0.0803 (7)
H13A	0.0740	0.7816	0.5472	0.096*
C14	0.0993 (4)	0.63297 (11)	0.55626 (9)	0.0614 (4)
H14A	−0.0247	0.6177	0.5328	0.074*
C15	0.1024 (3)	0.46329 (10)	0.43996 (7)	0.0444 (3)
C16	0.2983 (3)	0.50275 (13)	0.42434 (8)	0.0535 (4)
H16A	0.4023	0.5054	0.4584	0.064*
C17	0.3394 (3)	0.53842 (14)	0.35770 (9)	0.0631 (4)
H17A	0.4713	0.5644	0.3473	0.076*
C18	0.1862 (4)	0.53548 (13)	0.30698 (9)	0.0634 (5)
H18A	0.2147	0.5590	0.2624	0.076*
C19	−0.0101 (3)	0.49741 (13)	0.32258 (8)	0.0605 (4)
H19A	−0.1142	0.4958	0.2886	0.073*
C20	−0.0522 (3)	0.46158 (11)	0.38877 (8)	0.0514 (4)
H20A	−0.1848	0.4362	0.3990	0.062*

	U11	U22	U33	U12	U13	U23
N1	0.0362 (5)	0.0423 (6)	0.0445 (6)	−0.0035 (5)	0.0028 (5)	−0.0021 (5)
N2	0.0577 (7)	0.0453 (6)	0.0446 (6)	−0.0099 (6)	−0.0039 (6)	−0.0055 (5)
C1	0.0413 (7)	0.0367 (6)	0.0476 (7)	0.0000 (6)	0.0081 (6)	−0.0014 (6)
C2	0.0568 (9)	0.0541 (8)	0.0523 (8)	−0.0089 (7)	0.0006 (7)	0.0092 (7)
C3	0.0728 (11)	0.0777 (11)	0.0458 (8)	−0.0250 (10)	0.0162 (8)	−0.0067 (8)
C4	0.0529 (9)	0.0777 (11)	0.0716 (10)	−0.0188 (9)	0.0248 (8)	−0.0114 (10)
C5	0.0380 (7)	0.0664 (10)	0.0771 (11)	−0.0071 (7)	0.0026 (7)	−0.0018 (9)
C6	0.0510 (7)	0.0387 (6)	0.0462 (7)	−0.0117 (6)	0.0013 (6)	−0.0057 (6)
C7	0.0368 (6)	0.0378 (6)	0.0419 (6)	−0.0007 (5)	0.0043 (5)	−0.0047 (5)
C8	0.0455 (7)	0.0360 (6)	0.0427 (6)	0.0001 (6)	0.0007 (6)	−0.0060 (5)
C9	0.0560 (8)	0.0390 (7)	0.0376 (6)	−0.0067 (6)	0.0075 (6)	−0.0065 (5)
C10	0.0606 (9)	0.0534 (8)	0.0632 (9)	−0.0126 (8)	0.0026 (8)	−0.0113 (7)
C11	0.0866 (13)	0.0702 (12)	0.0738 (12)	−0.0356 (11)	0.0105 (11)	−0.0232 (10)
C12	0.148 (2)	0.0435 (9)	0.0617 (10)	−0.0306 (12)	0.0243 (14)	−0.0141 (8)
C13	0.142 (2)	0.0406 (8)	0.0581 (9)	0.0044 (11)	0.0039 (13)	−0.0052 (7)
C14	0.0894 (12)	0.0426 (7)	0.0522 (8)	0.0040 (8)	−0.0030 (9)	−0.0040 (6)
C15	0.0567 (8)	0.0340 (6)	0.0425 (7)	0.0010 (6)	0.0005 (6)	−0.0050 (5)
C16	0.0607 (9)	0.0529 (8)	0.0469 (7)	−0.0056 (8)	0.0019 (7)	−0.0016 (7)
C17	0.0737 (11)	0.0616 (9)	0.0539 (8)	−0.0074 (9)	0.0126 (8)	0.0062 (7)
C18	0.0919 (13)	0.0539 (8)	0.0443 (8)	0.0018 (9)	0.0072 (8)	0.0071 (7)
C19	0.0833 (12)	0.0513 (8)	0.0469 (8)	0.0057 (9)	−0.0121 (8)	0.0012 (7)
C20	0.0616 (9)	0.0428 (7)	0.0496 (8)	−0.0009 (7)	−0.0029 (7)	−0.0028 (6)

N1—C7	1.2680 (18)	C9—C14	1.378 (2)
N1—C1	1.4728 (17)	C9—C10	1.383 (2)
N2—C8	1.2745 (19)	C10—C11	1.393 (3)
N2—C6	1.4638 (19)	C10—H10A	0.9300
C1—C6	1.518 (2)	C11—C12	1.367 (4)
C1—C2	1.524 (2)	C11—H11A	0.9300
C1—H1B	0.9800	C12—C13	1.366 (4)
C2—C3	1.513 (2)	C12—H12A	0.9300
C2—H2B	0.9700	C13—C14	1.388 (3)
C2—H2C	0.9700	C13—H13A	0.9300
C3—C4	1.515 (3)	C14—H14A	0.9300
C3—H3A	0.9700	C15—C16	1.387 (2)
C3—H3B	0.9700	C15—C20	1.390 (2)
C4—C5	1.523 (3)	C16—C17	1.391 (2)
C4—H4A	0.9700	C16—H16A	0.9300
C4—H4B	0.9700	C17—C18	1.377 (3)
C5—C6	1.517 (2)	C17—H17A	0.9300
C5—H5A	0.9700	C18—C19	1.381 (3)
C5—H5B	0.9700	C18—H18A	0.9300
C6—H6A	0.9800	C19—C20	1.385 (2)
C7—C9	1.4996 (18)	C19—H19A	0.9300
C7—C8	1.5087 (18)	C20—H20A	0.9300
C8—C15	1.4914 (19)
C7—N1—C1	116.18 (11)	C9—C7—C8	120.12 (12)
C8—N2—C6	116.52 (12)	N2—C8—C15	116.95 (12)
N1—C1—C6	110.45 (11)	N2—C8—C7	120.82 (12)
N1—C1—C2	109.94 (12)	C15—C8—C7	122.18 (11)
C6—C1—C2	111.15 (12)	C14—C9—C10	119.24 (15)
N1—C1—H1B	108.4	C14—C9—C7	121.25 (14)
C6—C1—H1B	108.4	C10—C9—C7	119.49 (14)
C2—C1—H1B	108.4	C9—C10—C11	120.01 (19)
C3—C2—C1	111.32 (14)	C9—C10—H10A	120.0
C3—C2—H2B	109.4	C11—C10—H10A	120.0
C1—C2—H2B	109.4	C12—C11—C10	120.1 (2)
C3—C2—H2C	109.4	C12—C11—H11A	120.0
C1—C2—H2C	109.4	C10—C11—H11A	120.0
H2B—C2—H2C	108.0	C13—C12—C11	120.20 (17)
C2—C3—C4	111.43 (13)	C13—C12—H12A	119.9
C2—C3—H3A	109.3	C11—C12—H12A	119.9
C4—C3—H3A	109.3	C12—C13—C14	120.2 (2)
C2—C3—H3B	109.3	C12—C13—H13A	119.9
C4—C3—H3B	109.3	C14—C13—H13A	119.9
H3A—C3—H3B	108.0	C9—C14—C13	120.2 (2)
C3—C4—C5	110.93 (13)	C9—C14—H14A	119.9
C3—C4—H4A	109.5	C13—C14—H14A	119.9
C5—C4—H4A	109.5	C16—C15—C20	119.22 (14)
C3—C4—H4B	109.5	C16—C15—C8	121.16 (14)
C5—C4—H4B	109.5	C20—C15—C8	119.41 (14)
H4A—C4—H4B	108.0	C15—C16—C17	119.99 (16)
C6—C5—C4	110.90 (15)	C15—C16—H16A	120.0
C6—C5—H5A	109.5	C17—C16—H16A	120.0
C4—C5—H5A	109.5	C18—C17—C16	120.46 (18)
C6—C5—H5B	109.5	C18—C17—H17A	119.8
C4—C5—H5B	109.5	C16—C17—H17A	119.8
H5A—C5—H5B	108.0	C17—C18—C19	119.72 (15)
N2—C6—C5	110.33 (13)	C17—C18—H18A	120.1
N2—C6—C1	110.95 (11)	C19—C18—H18A	120.1
C5—C6—C1	112.96 (12)	C18—C19—C20	120.20 (17)
N2—C6—H6A	107.4	C18—C19—H19A	119.9
C5—C6—H6A	107.4	C20—C19—H19A	119.9
C1—C6—H6A	107.4	C19—C20—C15	120.39 (17)
N1—C7—C9	118.48 (12)	C19—C20—H20A	119.8
N1—C7—C8	121.37 (12)	C15—C20—H20A	119.8