Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801008984/cv6027sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801008984/cv6027Isup2.hkl |
CCDC reference: 170754
Key indicators
- Single-crystal X-ray study
- T = 296 K
- Mean (C-C) = 0.004 Å
- R factor = 0.055
- wR factor = 0.157
- Data-to-parameter ratio = 14.8
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
Alert Level C:
PLAT_420 Alert C D-H Without Acceptor N(2) - H(2B) ?
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check
2-(1,2,3,4-Tetrahydrocarbazole-2-yl)butyronitrile (5.0 g, 21.0 mmol) was added slowly to a suspension of lithium aluminium hydride (2.4 g, 62.0 mmol) in tetrahydrofuran (50 ml) at 273 K. The reaction mixture was refluxed for 5 h under a nitrogen atmosphere, then excess of lithium aluminium hydride was destroyed with methanol–water mixture (20:1) and extracted with ethyl acetate. The organic layer was dried with magnesium sulfate and the solvent was evaporated at reduced pressure. The residue was purified by column chromatography using silica gel, ethyl acetate–methanol (9:1) to afford 4.5 g (88%) of the product. The product was recrystallized from ethyl acetate–cyclohexane mixture (m.p. 425 K).
The positions of the H atoms were calculated geometrically at distances of 0.86 (NH and NH2), 0.93 and 0.98 (CH), 0.96 (CH3) and 0.97 (CH2) from the corresponding atoms, and a riding model was used during the refinement process.
Data collection: MolEN (Fair, 1990); cell refinement: MolEN; data reduction: MolEN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: MolEN.
C16H22N2 | Z = 2 |
Mr = 242.36 | F(000) = 264 |
Triclinic, P1 | Dx = 1.167 Mg m−3 |
a = 7.9665 (10) Å | Cu Kα radiation, λ = 1.54180 Å |
b = 8.911 (10) Å | Cell parameters from 25 reflections |
c = 10.7318 (10) Å | θ = 21–43° |
α = 69.59 (6)° | µ = 0.52 mm−1 |
β = 75.783 (10)° | T = 296 K |
γ = 80.87 (8)° | Rod, yellow |
V = 689.9 (8) Å3 | 0.30 × 0.25 × 0.20 mm |
Enraf-Nonius CAD-4 diffractometer | 1637 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.015 |
Graphite monochromator | θmax = 74.2°, θmin = 5.7° |
ω/2θ scans | h = 0→9 |
Absorption correction: ψ scan empirical (using intensity measurements) via ψ scans (Fair, 1990) | k = −10→11 |
Tmin = 0.855, Tmax = 0.901 | l = −12→13 |
2927 measured reflections | 3 standard reflections every 120 min |
2807 independent reflections | intensity decay: 1% |
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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.157 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0911P)2] where P = (Fo2 + 2Fc2)/3 |
2406 reflections | (Δ/σ)max < 0.001 |
163 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.21 e Å−3 |
C16H22N2 | γ = 80.87 (8)° |
Mr = 242.36 | V = 689.9 (8) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.9665 (10) Å | Cu Kα radiation |
b = 8.911 (10) Å | µ = 0.52 mm−1 |
c = 10.7318 (10) Å | T = 296 K |
α = 69.59 (6)° | 0.30 × 0.25 × 0.20 mm |
β = 75.783 (10)° |
Enraf-Nonius CAD-4 diffractometer | 1637 reflections with I > 2σ(I) |
Absorption correction: ψ scan empirical (using intensity measurements) via ψ scans (Fair, 1990) | Rint = 0.015 |
Tmin = 0.855, Tmax = 0.901 | 3 standard reflections every 120 min |
2927 measured reflections | intensity decay: 1% |
2807 independent reflections |
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.157 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.27 e Å−3 |
2406 reflections | Δρmin = −0.21 e Å−3 |
163 parameters |
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 | ||
C13 | −0.1054 (3) | −0.0112 (3) | 0.7310 (2) | 0.0523 (5) | |
H13A | −0.1215 | 0.0784 | 0.7655 | 0.063* | |
H13B | −0.0907 | 0.0322 | 0.6329 | 0.063* | |
C11 | 0.1092 (3) | −0.2434 (3) | 0.6975 (2) | 0.0542 (6) | |
H11A | 0.0043 | −0.2817 | 0.6928 | 0.065* | |
H11B | 0.1709 | −0.1947 | 0.6052 | 0.065* | |
N2 | −0.2607 (2) | −0.1008 (2) | 0.7869 (2) | 0.0568 (5) | |
H2A | −0.2524 | −0.2009 | 0.8341 | 0.068* | |
H2B | −0.3602 | −0.0533 | 0.7724 | 0.068* | |
C12 | 0.2219 (4) | −0.3857 (3) | 0.7682 (3) | 0.0721 (7) | |
H12A | 0.2487 | −0.4611 | 0.7190 | 0.108* | |
H12B | 0.1608 | −0.4367 | 0.8590 | 0.108* | |
H12C | 0.3276 | −0.3496 | 0.7713 | 0.108* | |
N9 | 0.3919 (2) | 0.2037 (2) | 0.91651 (18) | 0.0515 (5) | |
H9 | 0.3446 | 0.1797 | 1.0014 | 0.062* | |
C9A | 0.3388 (3) | 0.1611 (2) | 0.8210 (2) | 0.0444 (5) | |
C10 | 0.0581 (3) | −0.1151 (2) | 0.7672 (2) | 0.0458 (5) | |
H10 | 0.0302 | −0.1723 | 0.8651 | 0.055* | |
C8A | 0.5338 (3) | 0.2913 (2) | 0.8517 (2) | 0.0468 (5) | |
C5A | 0.5682 (3) | 0.3056 (2) | 0.7128 (2) | 0.0471 (5) | |
C4A | 0.4414 (3) | 0.2206 (2) | 0.6967 (2) | 0.0444 (5) | |
C3 | 0.2425 (3) | 0.1181 (3) | 0.6045 (2) | 0.0498 (5) | |
H3A | 0.1494 | 0.2030 | 0.6033 | 0.060* | |
H3B | 0.2407 | 0.0745 | 0.5338 | 0.060* | |
C1 | 0.1930 (3) | 0.0573 (3) | 0.8559 (2) | 0.0484 (5) | |
H1A | 0.0827 | 0.1206 | 0.8656 | 0.058* | |
H1B | 0.1968 | −0.0280 | 0.9414 | 0.058* | |
C2 | 0.2101 (3) | −0.0148 (2) | 0.7428 (2) | 0.0451 (5) | |
H2 | 0.3151 | −0.0890 | 0.7455 | 0.054* | |
C4 | 0.4174 (3) | 0.1894 (3) | 0.5742 (2) | 0.0498 (5) | |
H4A | 0.5113 | 0.1151 | 0.5488 | 0.060* | |
H4B | 0.4205 | 0.2890 | 0.4987 | 0.060* | |
C5 | 0.7104 (3) | 0.3901 (3) | 0.6258 (3) | 0.0558 (6) | |
H5 | 0.7362 | 0.4028 | 0.5336 | 0.067* | |
C8 | 0.6347 (3) | 0.3563 (3) | 0.9052 (3) | 0.0574 (6) | |
H8 | 0.6090 | 0.3463 | 0.9969 | 0.069* | |
C6 | 0.8103 (3) | 0.4533 (3) | 0.6798 (3) | 0.0655 (7) | |
H6 | 0.9044 | 0.5091 | 0.6227 | 0.079* | |
C7 | 0.7749 (3) | 0.4365 (3) | 0.8176 (3) | 0.0685 (7) | |
H7 | 0.8463 | 0.4797 | 0.8510 | 0.082* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C13 | 0.0430 (11) | 0.0560 (12) | 0.0546 (13) | −0.0018 (9) | −0.0129 (10) | −0.0127 (10) |
C11 | 0.0553 (13) | 0.0535 (12) | 0.0583 (14) | −0.0045 (10) | −0.0115 (11) | −0.0236 (10) |
N2 | 0.0406 (10) | 0.0665 (11) | 0.0592 (12) | −0.0007 (8) | −0.0140 (8) | −0.0145 (9) |
C12 | 0.0791 (18) | 0.0563 (14) | 0.0874 (19) | 0.0098 (12) | −0.0256 (15) | −0.0321 (13) |
N9 | 0.0532 (11) | 0.0572 (10) | 0.0454 (10) | −0.0117 (8) | −0.0069 (8) | −0.0170 (8) |
C9A | 0.0448 (11) | 0.0455 (10) | 0.0455 (11) | −0.0031 (8) | −0.0092 (9) | −0.0182 (8) |
C10 | 0.0415 (11) | 0.0475 (11) | 0.0477 (11) | −0.0034 (8) | −0.0100 (9) | −0.0143 (9) |
C8A | 0.0474 (12) | 0.0452 (10) | 0.0490 (11) | −0.0063 (9) | −0.0105 (9) | −0.0149 (9) |
C5A | 0.0470 (12) | 0.0375 (10) | 0.0549 (12) | −0.0007 (8) | −0.0098 (9) | −0.0141 (9) |
C4A | 0.0451 (11) | 0.0397 (10) | 0.0475 (11) | −0.0045 (8) | −0.0080 (9) | −0.0134 (8) |
C3 | 0.0522 (13) | 0.0527 (12) | 0.0458 (11) | −0.0063 (9) | −0.0116 (9) | −0.0158 (9) |
C1 | 0.0463 (12) | 0.0547 (12) | 0.0450 (11) | −0.0090 (9) | −0.0070 (9) | −0.0167 (9) |
C2 | 0.0418 (11) | 0.0445 (10) | 0.0501 (12) | −0.0012 (8) | −0.0110 (9) | −0.0167 (9) |
C4 | 0.0488 (12) | 0.0546 (12) | 0.0445 (11) | −0.0088 (9) | −0.0032 (9) | −0.0167 (9) |
C5 | 0.0579 (14) | 0.0512 (12) | 0.0554 (13) | −0.0120 (10) | −0.0028 (10) | −0.0165 (10) |
C8 | 0.0624 (14) | 0.0589 (13) | 0.0561 (13) | −0.0117 (11) | −0.0156 (11) | −0.0196 (10) |
C6 | 0.0619 (15) | 0.0591 (14) | 0.0774 (18) | −0.0218 (12) | −0.0097 (13) | −0.0203 (12) |
C7 | 0.0695 (17) | 0.0642 (15) | 0.0811 (19) | −0.0205 (13) | −0.0219 (14) | −0.0241 (13) |
C13—N2 | 1.463 (3) | C8A—C5A | 1.411 (3) |
C13—C10 | 1.523 (3) | C5A—C5 | 1.408 (3) |
C13—H13A | 0.9700 | C5A—C4A | 1.430 (3) |
C13—H13B | 0.9700 | C4A—C4 | 1.495 (3) |
C11—C12 | 1.514 (4) | C3—C2 | 1.534 (3) |
C11—C10 | 1.527 (3) | C3—C4 | 1.538 (3) |
C11—H11A | 0.9700 | C3—H3A | 0.9700 |
C11—H11B | 0.9700 | C3—H3B | 0.9700 |
N2—H2A | 0.8600 | C1—C2 | 1.529 (3) |
N2—H2B | 0.8600 | C1—H1A | 0.9700 |
C12—H12A | 0.9600 | C1—H1B | 0.9700 |
C12—H12B | 0.9600 | C2—H2 | 0.9800 |
C12—H12C | 0.9600 | C4—H4A | 0.9700 |
N9—C8A | 1.373 (3) | C4—H4B | 0.9700 |
N9—C9A | 1.382 (3) | C5—C6 | 1.371 (3) |
N9—H9 | 0.8600 | C5—H5 | 0.9300 |
C9A—C4A | 1.356 (3) | C8—C7 | 1.382 (4) |
C9A—C1 | 1.493 (3) | C8—H8 | 0.9300 |
C10—C2 | 1.536 (3) | C6—C7 | 1.395 (4) |
C10—H10 | 0.9800 | C6—H6 | 0.9300 |
C8A—C8 | 1.385 (3) | C7—H7 | 0.9300 |
N2—C13—C10 | 112.42 (18) | C9A—C4A—C5A | 106.90 (19) |
N2—C13—H13A | 109.1 | C9A—C4A—C4 | 122.26 (19) |
C10—C13—H13A | 109.1 | C5A—C4A—C4 | 130.81 (19) |
N2—C13—H13B | 109.1 | C2—C3—C4 | 112.18 (18) |
C10—C13—H13B | 109.1 | C2—C3—H3A | 109.2 |
H13A—C13—H13B | 107.9 | C4—C3—H3A | 109.2 |
C12—C11—C10 | 114.1 (2) | C2—C3—H3B | 109.2 |
C12—C11—H11A | 108.7 | C4—C3—H3B | 109.2 |
C10—C11—H11A | 108.7 | H3A—C3—H3B | 107.9 |
C12—C11—H11B | 108.7 | C9A—C1—C2 | 109.09 (18) |
C10—C11—H11B | 108.7 | C9A—C1—H1A | 109.9 |
H11A—C11—H11B | 107.6 | C2—C1—H1A | 109.9 |
C13—N2—H2A | 120.0 | C9A—C1—H1B | 109.9 |
C13—N2—H2B | 120.0 | C2—C1—H1B | 109.9 |
H2A—N2—H2B | 120.0 | H1A—C1—H1B | 108.3 |
C11—C12—H12A | 109.5 | C1—C2—C3 | 109.37 (17) |
C11—C12—H12B | 109.5 | C1—C2—C10 | 112.13 (18) |
H12A—C12—H12B | 109.5 | C3—C2—C10 | 114.98 (18) |
C11—C12—H12C | 109.5 | C1—C2—H2 | 106.6 |
H12A—C12—H12C | 109.5 | C3—C2—H2 | 106.6 |
H12B—C12—H12C | 109.5 | C10—C2—H2 | 106.6 |
C8A—N9—C9A | 107.85 (18) | C4A—C4—C3 | 110.11 (17) |
C8A—N9—H9 | 126.1 | C4A—C4—H4A | 109.6 |
C9A—N9—H9 | 126.1 | C3—C4—H4A | 109.6 |
C4A—C9A—N9 | 110.46 (19) | C4A—C4—H4B | 109.6 |
C4A—C9A—C1 | 126.41 (19) | C3—C4—H4B | 109.6 |
N9—C9A—C1 | 123.07 (19) | H4A—C4—H4B | 108.2 |
C13—C10—C11 | 112.46 (18) | C6—C5—C5A | 118.8 (2) |
C13—C10—C2 | 112.44 (18) | C6—C5—H5 | 120.6 |
C11—C10—C2 | 111.85 (18) | C5A—C5—H5 | 120.6 |
C13—C10—H10 | 106.5 | C7—C8—C8A | 117.8 (2) |
C11—C10—H10 | 106.5 | C7—C8—H8 | 121.1 |
C2—C10—H10 | 106.5 | C8A—C8—H8 | 121.1 |
N9—C8A—C8 | 129.2 (2) | C5—C6—C7 | 122.0 (2) |
N9—C8A—C5A | 108.23 (18) | C5—C6—H6 | 119.0 |
C8—C8A—C5A | 122.5 (2) | C7—C6—H6 | 119.0 |
C5—C5A—C8A | 118.3 (2) | C8—C7—C6 | 120.6 (2) |
C5—C5A—C4A | 135.1 (2) | C8—C7—H7 | 119.7 |
C8A—C5A—C4A | 106.56 (19) | C6—C7—H7 | 119.7 |
C8A—N9—C9A—C4A | −0.7 (2) | C4A—C9A—C1—C2 | 17.2 (3) |
C8A—N9—C9A—C1 | 176.66 (18) | N9—C9A—C1—C2 | −159.75 (18) |
N2—C13—C10—C11 | 68.0 (2) | C9A—C1—C2—C3 | −47.7 (2) |
N2—C13—C10—C2 | −164.71 (18) | C9A—C1—C2—C10 | −176.46 (16) |
C12—C11—C10—C13 | −157.4 (2) | C4—C3—C2—C1 | 65.0 (2) |
C12—C11—C10—C2 | 74.9 (3) | C4—C3—C2—C10 | −167.82 (16) |
C9A—N9—C8A—C8 | −178.1 (2) | C13—C10—C2—C1 | 78.1 (2) |
C9A—N9—C8A—C5A | 0.8 (2) | C11—C10—C2—C1 | −154.29 (18) |
N9—C8A—C5A—C5 | −179.38 (18) | C13—C10—C2—C3 | −47.7 (2) |
C8—C8A—C5A—C5 | −0.4 (3) | C11—C10—C2—C3 | 79.9 (2) |
N9—C8A—C5A—C4A | −0.7 (2) | C9A—C4A—C4—C3 | 12.7 (3) |
C8—C8A—C5A—C4A | 178.36 (19) | C5A—C4A—C4—C3 | −169.88 (19) |
N9—C9A—C4A—C5A | 0.3 (2) | C2—C3—C4—C4A | −45.1 (2) |
C1—C9A—C4A—C5A | −176.98 (18) | C8A—C5A—C5—C6 | 0.7 (3) |
N9—C9A—C4A—C4 | 178.23 (18) | C4A—C5A—C5—C6 | −177.6 (2) |
C1—C9A—C4A—C4 | 1.0 (3) | N9—C8A—C8—C7 | 178.2 (2) |
C5—C5A—C4A—C9A | 178.6 (2) | C5A—C8A—C8—C7 | −0.6 (3) |
C8A—C5A—C4A—C9A | 0.2 (2) | C5A—C5—C6—C7 | −0.1 (4) |
C5—C5A—C4A—C4 | 0.9 (4) | C8A—C8—C7—C6 | 1.2 (4) |
C8A—C5A—C4A—C4 | −177.5 (2) | C5—C6—C7—C8 | −0.9 (4) |
Experimental details
Crystal data | |
Chemical formula | C16H22N2 |
Mr | 242.36 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 296 |
a, b, c (Å) | 7.9665 (10), 8.911 (10), 10.7318 (10) |
α, β, γ (°) | 69.59 (6), 75.783 (10), 80.87 (8) |
V (Å3) | 689.9 (8) |
Z | 2 |
Radiation type | Cu Kα |
µ (mm−1) | 0.52 |
Crystal size (mm) | 0.30 × 0.25 × 0.20 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | ψ scan empirical (using intensity measurements) via ψ scans (Fair, 1990) |
Tmin, Tmax | 0.855, 0.901 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2927, 2807, 1637 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.624 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.157, 1.04 |
No. of reflections | 2406 |
No. of parameters | 163 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.27, −0.21 |
Computer programs: MolEN (Fair, 1990), MolEN, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976).
C13—N2 | 1.463 (3) | C5A—C5 | 1.408 (3) |
N9—C8A | 1.373 (3) | C5A—C4A | 1.430 (3) |
N9—C9A | 1.382 (3) | C4A—C4 | 1.495 (3) |
C9A—C4A | 1.356 (3) | C1—C2 | 1.529 (3) |
C9A—C1 | 1.493 (3) | C5—C6 | 1.371 (3) |
C8A—C8 | 1.385 (3) | C8—C7 | 1.382 (4) |
C8A—C5A | 1.411 (3) | C6—C7 | 1.395 (4) |
C4A—C9A—C1 | 126.41 (19) | C8A—C5A—C4A | 106.56 (19) |
N9—C9A—C1 | 123.07 (19) | C9A—C4A—C5A | 106.90 (19) |
N9—C8A—C8 | 129.2 (2) | C9A—C4A—C4 | 122.26 (19) |
C8—C8A—C5A | 122.5 (2) | C5A—C4A—C4 | 130.81 (19) |
C5—C5A—C8A | 118.3 (2) | C2—C3—C4 | 112.18 (18) |
C5—C5A—C4A | 135.1 (2) | C4A—C4—C3 | 110.11 (17) |
C1—C9A—C4A—C4 | 1.0 (3) | C4—C3—C2—C1 | 65.0 (2) |
C4A—C9A—C1—C2 | 17.2 (3) | C9A—C4A—C4—C3 | 12.7 (3) |
C9A—C1—C2—C3 | −47.7 (2) | C2—C3—C4—C4A | −45.1 (2) |
Angles | (I) | (VI) | (VII) | (IX) | (X) | (XI) |
C2-C3-C4 | 112.2 (2) | 109.9 (2) | 110.5 (4) | 114.6 (5) | 114.7 (2) | 115.1 (2) |
C4-C4a-C5a | 130.8 (2) | 128.6 (2) | 129.9 (4) | 130.4 (4) | 130.9 (2) | 127.5 (2) |
C3-C4-C4a | 110.1 (2) | 109.0 (2) | 110.1 (4) | 116.5 (4) | 115.9 (2) | 114.6 (2) |
C1-C9a-N9 | 123.1 (2) | 126.7 (2) | 125.0 (3) | 126.8 (4) | 126.4 (2) | 127.5 (2) |
C4a-C5a-C5 | 135.1 (2) | 134.7 (2) | 133.6 (4) | 132.2 (4) | 134.7 (2) | 134.0 (3) |
C4-C4a-C9a | 122.3 (2) | 124.2 (3) | 124.0 (4) | 121.5 (4) | 122.0 (2) | 124.5 (2) |
N9-C8a-C8 | 129.2 (2) | 129.1 (2) | 130.8 (4) | 131.0 (4) | 129.8 (2) | 129.4 (3) |
1,2,3,4-Tetrahydrocarbazole derivatives can be considered to be synthetic precursors of tetracyclic indole alkaloids. They have tricyclic ring systems with the rings named as A, B and C as in the strychnos type of indole alkaloids (Bosch & Bonjoch, 1988). The possibility of synthesizing the indole type of alkaloids by substitution at different positions is currently under investigation (Patır et al., 1997).
Tetrahydrocarbazole systems are present in the framework of a number of indole-type alkaloids of biological interest (Phillipson & Zenk, 1980; Saxton, 1983; Abraham, 1975).
The structures of tetrahydrocarbazole derivatives having different substituents at different positions of the carbazole core, e.g. 4-methylcarbazole-3-carboxylic acid, (II) (Hökelek et al., 2001), 1-benzyloxy-1,2,3,4-tetrahydrocarbazole, (III) (Hökelek et al., 2000), N-(1,2,3,4-tetrahydrocarbazole-1-yl)-2-methoxyacetamide, (IV) (Hökelek & Patır, 2000a), 2,3-dihydro-3-ethyl-9-(phenylsulfonyl)carbazol-4(1H)-one, (V) (Hökelek & Patır, 2000b), N-(2,2-dimethoxyethyl)-N-(9-methoxymethyl-1,2,3,4-tetrahydrospiro[carbazole- 1,2'-[1,3]dithiolan]-4-yl)benzamide, (VI) (Hökelek & Patır, 1999) and 1,2,3,4-tetrahydrocarbazole-1-spiro-2'-[1,3]dithiolane, (VII) (Hökelek et al., 1994) have been the subject of much interest in our laboratory.
The title compound, (I), may be an interesting intermediate in the synthesis of tetracyclic indole alkaloids (Magnus et al., 1992).
The present structure determination of (I) was undertaken in order to understand the effects of the butylamine side chain at position 2 on the geometry of the carbazole system, and to compare the obtained results with those of previously reported tetrahydrocarbazole derivatives.
Compound (I) (Fig. 1) contains a carbazole skeleton with a butylamine side chain bonded as substituent at position 2. As can be seen from the packing diagram (Fig. 2), there are intermolecular hydrogen bonding and intermolecular contact between the indole N—H group and side-chain NH2 groups of the neighbouring molecules [N2i···H9(N9) 2.096 Å, N9—H9···N2i 172.1° and N9i···H2A 2.626 Å, N2—H2A···N9i 103.6°, respectively; symmetry code: (i) -x, -y, -z + 2]. These intermolecular hydrogen bonding and contact cause dimerization of the substituted carbazole molecules. Dipole–dipole and van der Waals interactions are also effective in the molecular packing. The substituent and the intermolecular interactions may cause increases in the exocyclic and endocyclic angles C4—C4A—C5A [130.8 (2)°], C5—C5A—C4A [135.1 (2)°], C2—C3—C4 [112.2 (2)°] and C1—C9A—C4A [126.4 (2)°].
The absence of any protecting group at atom N9 causes shortening of the C—N bonds [N9—C8A 1.373 (3) Å and N9—C9A 1.382 (3) Å]. They are shorter than the corresponding values [1.390 (10) and 1.404 (9) Å] in N-(2-methoxyethyl)-N-(2,3,4,9-tetrahydrospiro[1H-carbazole-1,2-(1,3)dithiolane]- 4-yl)benzenesulfonamide, (VIII) (Patır et al., 1997) and [1.423 (5) and 1.412 (5) Å] in 2,3-dihydro-9-(phenylsulfonyl)carbazole-4-(1H)-one, (IX) (Hökelek et al., 1994). On the other hand, N9—C8A is nearly the same, but N9—C9A is longer than the corresponding values [1.382 (2) and 1.355 (3) Å] in spiro[carbazole-1(2H),2'-[1,3]-dithiolan]-4(3H)-one, (X) (Hökelek et al., 1998), while N9—C8A is shorter and N9—C9A is nearly the same with respect to the corresponding ones [1.396 (2) and 1.377 (2) Å] in 9-acetonyl-3-ethylidene-1,2,3,4-tetrahydrospiro[carbazole-1,2'-[1,3]dithiolan]- 4-one, (XI) (Hökelek et al., 1999).
The butylamine side chain in (I) causes notable changes on the geometry of the carbazole core, compared with the reported values in compounds (VI), (VII), (IX), (X) and (XI) (Table 2).
In conclusion, the types of substituent groups, depending on their electron releasing/denoting properties, and their bonding positions have a significant effect on the geometry of the carbazole core.
An examination of the deviations from the least-squares planes through the individual rings shows that rings A (C5A/C5–C8/C8A) and B (C4A/C5A/C8A/N9/C9A) are nearly planar and ring C (C1—C4/C4A/C9A) is not planar, with a maximum deviation for the C3 [0.340 (3) Å] atom. These rings are also twisted with respect to each other. The dihedral angles between the best least-squares planes are A/B = 1.63 (8), A/C = 8.21 (7) and B/C = 6.84 (8)°. In ring C, the puckering parameters, i.e. the angles between the best planes C1/C3/C4/C9A, C4/C4a/C9A and C1/C2/C3, are 7.0 (2) and 50.6 (2)°, respectively. Ring C has a sofa conformation with a local pseudo-twofold axis running along the midpoints of the C2—C3 and C4a—C9A bonds.