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Acta Cryst. (2008). E64, o359    [ doi:10.1107/S1600536807067505 ]

(4aR,8aR)-2,3-Diphenyl-4a,5,6,7,8,8a-hexahydroquinoxaline

G.-X. Wang and H.-Y. Ye

Abstract top

The title molecule, C20H20N2, is chiral; the absolute configuration follows from the known chirality of the input reagents. In addition to van der Waals forces, C-H...[pi] ring interactions are also present. The angle between the planes of the phenyl rings is 65.6 (1)°. The heterocyclic ring of the quinoxaline system has a twist-boat configuration, while the cyclohexane ring has a chair configuration.

Comment top

Presence of chiral centres in organic ligands is important for synthesis of chiral coordination polymers (Qu et al., 2004). We report here the crystal structure of (4aR,8aR)-4a,5,6,7,8,8a-hexahydro-2,3-diphenylquinoxaline (Fig. 1).

The lengths of the C?N double bonds (1.276 (3) and 1.278 (3) Å) are similar as in the following compounds containing the C?N double bonds: tris[(5-bromosalicylidene)aminoethyl]amine (Figuet et al. (2001) and N,N'-bis(salicylidene)-1,4,butanediamine (Kennedy et al.(2001).

Related literature top

For examples of the synthesis of non-centrosymmetric solid materials by reactions of chiral organic ligands and inorganic salts, see: Qu et al. (2004). For the geometric parameters of C?N bonds, see: Figuet et al. (2001); Kennedy & Reglinski (2001).

Experimental top

Benzil (2.10 g, 10.0 mmol) and (1R,2R)-(-)-diaminocyclohexane (1.20 g, 10.5 mmol) were dissolved in methanol (20 ml) containing sulfuric acid (0.08 g) as a catalytic agent. The solution was stirred at room temperature. After 4 h, a yellow precipitate appeared. It was filtered off and washed with chilled methanol (10 ml). The crude product was recrystallized by slow evaporation of the saturated ethanol solution. Yellow block-like crystals with dimensions of tenths of mm were isolated.

Refinement top

All the H atoms could be found in the difference Fourier maps. Nevertheless, they were placed into the idealized positions and refined in a riding atom approximation with following constraints: Cmethine—Hmethine = 0.98; Cmethylene—Hmethylene = 0.97; Caryl—Haryl = 0.93 Å; UisoH = 1.2UeqC in all the cases. In the absence of significant anomalous scattering effects, 1531 Friedel pairs were merged. The absolute configuration was determined by synthesis. The chiral reactant (1R,2R)-(-)-diaminocyclohexane was used.

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 1999).

Figures top
[Figure 1] Fig. 1. A view of the title compound with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
[Figure 2] Fig. 2. The crystal packing of the title compound viewed along the a axis.
(4aR,8aR)-2,3-Diphenyl-4a,5,6,7,8,8a-hexahydroquinoxaline top
Crystal data top
C20H20N2F000 = 616
Mr = 288.38Dx = 1.207 Mg m−3
Orthorhombic, P212121Mo Kα radiation
λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 3447 reflections
a = 5.6253 (11) Åθ = 3.4–27.5º
b = 15.402 (3) ŵ = 0.07 mm−1
c = 18.315 (4) ÅT = 293 (2) K
V = 1586.8 (5) Å3Block, yellow
Z = 40.12 × 0.08 × 0.05 mm
Data collection top
Rigaku SCXmini
diffractometer		2134 independent reflections
Radiation source: fine-focus sealed tube1880 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.053
Detector resolution: 13.6612 pixels mm-1θmax = 27.6º
T = 293(2) Kθmin = 3.5º
ω scansh = −7→7
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2005)		k = −19→20
Tmin = 0.901, Tmax = 1.000l = −23→23
15676 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.056H-atom parameters constrained
wR(F2) = 0.132  w = 1/[σ2(Fo2) + (0.0548P)2 + 0.1683P]
where P = (Fo2 + 2Fc2)/3
S = 1.19(Δ/σ)max < 0.001
2134 reflectionsΔρmax = 0.13 e Å−3
200 parametersΔρmin = −0.13 e Å−3
80 constraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.010 (2)
Crystal data top
C20H20N2V = 1586.8 (5) Å3
Mr = 288.38Z = 4
Orthorhombic, P212121Mo Kα
a = 5.6253 (11) ŵ = 0.07 mm−1
b = 15.402 (3) ÅT = 293 (2) K
c = 18.315 (4) Å0.12 × 0.08 × 0.05 mm
Data collection top
Rigaku SCXmini
diffractometer		2134 independent reflections
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2005)		1880 reflections with I > 2σ(I)
Tmin = 0.901, Tmax = 1.000Rint = 0.053
15676 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.056Δρmax = 0.13 e Å−3
wR(F2) = 0.132Δρmin = −0.13 e Å−3
S = 1.19Absolute structure: ?
2134 reflectionsFlack parameter: ?
200 parametersRogers parameter: ?
H-atom parameters constrained
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.7959 (6)0.65882 (17)0.09928 (14)0.0512 (7)
H1A0.68410.62880.13160.061*
C20.7195 (7)0.75311 (18)0.09215 (16)0.0645 (8)
H2A0.55680.75570.07480.077*
H2B0.81980.78220.05670.077*
C30.7381 (7)0.7995 (2)0.16551 (17)0.0699 (9)
H3A0.70040.86050.15890.084*
H3B0.62210.77520.19890.084*
C40.9823 (7)0.79159 (18)0.19858 (17)0.0659 (9)
H4A0.98240.81800.24670.079*
H4B1.09580.82270.16850.079*
C51.0578 (7)0.69734 (16)0.20496 (15)0.0592 (8)
H5A1.21960.69440.22310.071*
H5B0.95560.66780.23960.071*
C61.0429 (5)0.65242 (16)0.13156 (14)0.0511 (7)
H6A1.15400.68110.09820.061*
C71.0503 (5)0.51148 (15)0.08549 (13)0.0476 (6)
C81.1020 (5)0.41698 (17)0.09128 (14)0.0503 (7)
C91.3120 (6)0.39001 (19)0.12512 (15)0.0583 (7)
H9A1.41920.43070.14300.070*
C101.3595 (7)0.3016 (2)0.13178 (17)0.0673 (9)
H10A1.49890.28340.15440.081*
C111.2019 (7)0.24103 (19)0.10512 (18)0.0684 (9)
H11A1.23490.18210.10940.082*
C120.9971 (7)0.26799 (18)0.07241 (16)0.0656 (9)
H12A0.88940.22700.05520.079*
C130.9474 (6)0.35524 (17)0.06444 (15)0.0565 (7)
H13A0.80890.37250.04080.068*
C140.9184 (5)0.54805 (16)0.02031 (14)0.0464 (6)
C150.9435 (5)0.50996 (15)−0.05353 (13)0.0450 (6)
C161.1486 (5)0.46658 (17)−0.07485 (15)0.0541 (7)
H16A1.26790.4558−0.04090.065*
C171.1760 (6)0.43947 (19)−0.14618 (15)0.0601 (7)
H17A1.31420.4108−0.16010.072*
C181.0006 (6)0.45455 (18)−0.19673 (15)0.0600 (8)
H18A1.02130.4365−0.24480.072*
C190.7950 (6)0.49611 (19)−0.17673 (15)0.0578 (7)
H19A0.67590.5059−0.21100.069*
C200.7659 (6)0.52341 (16)−0.10515 (14)0.0511 (6)
H20A0.62580.5511−0.09150.061*
N11.1133 (5)0.56069 (14)0.13814 (12)0.0557 (6)
N20.7915 (5)0.61639 (14)0.02727 (12)0.0526 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0596 (17)0.0478 (14)0.0463 (13)0.0055 (13)0.0037 (13)−0.0004 (11)
C20.084 (2)0.0535 (16)0.0564 (16)0.0211 (17)−0.0011 (17)−0.0020 (12)
C30.094 (3)0.0526 (16)0.0631 (18)0.0175 (18)0.0079 (19)−0.0023 (13)
C40.091 (3)0.0436 (14)0.0631 (17)−0.0021 (17)0.0042 (18)−0.0010 (13)
C50.077 (2)0.0467 (14)0.0543 (15)−0.0056 (16)−0.0053 (15)0.0005 (12)
C60.0606 (17)0.0410 (13)0.0517 (14)0.0015 (13)0.0003 (14)0.0025 (11)
C70.0542 (15)0.0415 (12)0.0471 (13)0.0037 (12)−0.0003 (12)0.0030 (10)
C80.0596 (17)0.0469 (13)0.0445 (13)0.0065 (13)0.0057 (13)0.0069 (11)
C90.0608 (18)0.0550 (15)0.0590 (16)0.0095 (15)−0.0028 (14)0.0039 (13)
C100.078 (2)0.0612 (18)0.0628 (18)0.0265 (18)0.0031 (18)0.0132 (14)
C110.095 (3)0.0447 (14)0.0657 (18)0.0139 (18)0.0167 (19)0.0102 (14)
C120.085 (2)0.0454 (14)0.0665 (18)−0.0041 (16)0.0073 (18)0.0080 (13)
C130.0631 (18)0.0472 (13)0.0592 (16)0.0006 (14)−0.0009 (15)0.0066 (12)
C140.0490 (14)0.0417 (12)0.0486 (13)−0.0007 (12)−0.0001 (11)0.0031 (10)
C150.0494 (14)0.0380 (11)0.0477 (13)−0.0027 (12)0.0028 (11)0.0051 (10)
C160.0528 (16)0.0557 (15)0.0537 (14)0.0044 (13)0.0025 (13)0.0015 (12)
C170.0623 (18)0.0584 (16)0.0596 (16)0.0021 (15)0.0103 (15)−0.0048 (14)
C180.079 (2)0.0521 (15)0.0490 (14)−0.0030 (16)0.0042 (15)−0.0046 (12)
C190.0713 (19)0.0506 (14)0.0513 (14)−0.0014 (15)−0.0106 (15)0.0051 (12)
C200.0562 (16)0.0431 (13)0.0539 (14)0.0002 (13)−0.0018 (13)0.0043 (11)
N10.0655 (15)0.0453 (11)0.0563 (13)0.0060 (12)−0.0078 (12)0.0012 (10)
N20.0574 (14)0.0507 (12)0.0499 (12)0.0069 (12)−0.0034 (11)0.0012 (10)
Geometric parameters (Å, °) top
C1—N21.472 (3)C9—C101.393 (4)
C1—C61.513 (4)C9—H9A0.9300
C1—C21.520 (4)C10—C111.377 (5)
C1—H1A0.9800C10—H10A0.9300
C2—C31.525 (4)C11—C121.363 (5)
C2—H2A0.9700C11—H11A0.9300
C2—H2B0.9700C12—C131.380 (4)
C3—C41.506 (6)C12—H12A0.9300
C3—H3A0.9700C13—H13A0.9300
C3—H3B0.9700C14—N21.278 (3)
C4—C51.517 (4)C14—C151.481 (3)
C4—H4A0.9700C15—C161.389 (4)
C4—H4B0.9700C15—C201.391 (4)
C5—C61.514 (4)C16—C171.380 (4)
C5—H5A0.9700C16—H16A0.9300
C5—H5B0.9700C17—C181.373 (5)
C6—N11.472 (3)C17—H17A0.9300
C6—H6A0.9800C18—C191.372 (5)
C7—N11.276 (3)C18—H18A0.9300
C7—C81.488 (3)C19—C201.387 (4)
C7—C141.514 (3)C19—H19A0.9300
C8—C131.379 (4)C20—H20A0.9300
C8—C91.397 (4)
N2—C1—C6109.6 (2)C13—C8—C7121.7 (3)
N2—C1—C2110.0 (2)C9—C8—C7119.2 (3)
C6—C1—C2110.8 (3)C10—C9—C8119.5 (3)
N2—C1—H1A108.8C10—C9—H9A120.3
C6—C1—H1A108.8C8—C9—H9A120.3
C2—C1—H1A108.8C11—C10—C9120.5 (3)
C1—C2—C3110.7 (2)C11—C10—H10A119.7
C1—C2—H2A109.5C9—C10—H10A119.7
C3—C2—H2A109.5C12—C11—C10119.6 (3)
C1—C2—H2B109.5C12—C11—H11A120.2
C3—C2—H2B109.5C10—C11—H11A120.2
H2A—C2—H2B108.1C11—C12—C13120.9 (3)
C4—C3—C2112.2 (3)C11—C12—H12A119.5
C4—C3—H3A109.2C13—C12—H12A119.5
C2—C3—H3A109.2C8—C13—C12120.4 (3)
C4—C3—H3B109.2C8—C13—H13A119.8
C2—C3—H3B109.2C12—C13—H13A119.8
H3A—C3—H3B107.9N2—C14—C15118.1 (2)
C3—C4—C5111.3 (3)N2—C14—C7120.1 (2)
C3—C4—H4A109.4C15—C14—C7121.7 (2)
C5—C4—H4A109.4C16—C15—C20118.5 (2)
C3—C4—H4B109.4C16—C15—C14121.8 (2)
C5—C4—H4B109.4C20—C15—C14119.6 (2)
H4A—C4—H4B108.0C17—C16—C15120.3 (3)
C6—C5—C4110.7 (2)C17—C16—H16A119.9
C6—C5—H5A109.5C15—C16—H16A119.9
C4—C5—H5A109.5C18—C17—C16120.5 (3)
C6—C5—H5B109.5C18—C17—H17A119.8
C4—C5—H5B109.5C16—C17—H17A119.8
H5A—C5—H5B108.1C19—C18—C17120.3 (3)
N1—C6—C1110.0 (2)C19—C18—H18A119.8
N1—C6—C5110.5 (2)C17—C18—H18A119.8
C1—C6—C5111.6 (2)C18—C19—C20119.6 (3)
N1—C6—H6A108.2C18—C19—H19A120.2
C1—C6—H6A108.2C20—C19—H19A120.2
C5—C6—H6A108.2C19—C20—C15120.9 (3)
N1—C7—C8118.2 (2)C19—C20—H20A119.6
N1—C7—C14120.7 (2)C15—C20—H20A119.6
C8—C7—C14121.1 (2)C7—N1—C6115.7 (2)
C13—C8—C9119.1 (3)C14—N2—C1116.5 (2)
Table 1
D—H···π-ring interactions calculated by PLATON (Spek, 2003) top
D–H···CgD—HH···CgD···CgD—H···Cg
C3—H3A···Cg1i0.972.823.761 (4)164
C4—H4A···Cg2ii0.972.943.840 (3)154
C11—H11A···Cg1iii0.932.873.769 (3)164
Symmetry codes:(i) -1/2+x,3/2-y,-z; (ii) 2-x,1/2+y,1/2-z; (iii) 1/2+x,1/2-y,-z. Cg1 and Cg2 are the centroids of the phenyl rings C15–C20 C8–C13, respectively.
Acknowledgements top

This work was supported by a Start-up Grant from Southeast University to Dr Heng-Yun Ye.

references
References top

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Sheldrick, G. M. (1999). SHELXTL/PC. Version 5.1. Bruker AXS Inc., Madison, Wisconsin, USA.

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