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The indole and pyrrolidine ring systems of the title compound, C20H22N2O2S, are essentially coplanar. The angle between the planes of the phenyl­sulfonyl group and the indole ring system is 80.2 (2)°. The pyrrolidine N atom has bond angles totalling 343.1°, indicating some flattening from a purely pyramidal N atom, compared with 324° for ammonia.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807032412/fl2137sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807032412/fl2137Isup2.hkl
Contains datablock I

CCDC reference: 657693

Key indicators

  • Single-crystal X-ray study
  • T = 296 K
  • Mean [sigma](C-C) = 0.008 Å
  • R factor = 0.062
  • wR factor = 0.283
  • Data-to-parameter ratio = 17.8

checkCIF/PLATON results

No syntax errors found



Alert level B PLAT031_ALERT_4_B Refined Extinction Parameter within Range ...... 1.22 Sigma
Alert level C RFACR01_ALERT_3_C The value of the weighted R factor is > 0.25 Weighted R factor given 0.283 PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low .... 43 Perc. PLAT084_ALERT_2_C High R2 Value .................................. 0.28 PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given ....... ? PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ... 8
0 ALERT level A = In general: serious problem 1 ALERT level B = Potentially serious problem 5 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 3 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

The title compound, C20H22N2O2S, was synthesized as a precursor to the corresponding pyrrolo[3,4-b]indole as a stable synthetic analogue of indole-2,3-quinodimethane. The tert-butyl group was chosen to block oxidation of the pyrrolidine ring by adventitious oxygen, a side-reaction that is more pronounced with the isopropyl analogue discussed in the preceding paper (Kishbaugh et al., 2007). The X-ray crystallographic analysis confirms the molecular structure and atom connectivity for (I) that we had proposed for this compound based on NMR spectroscopy and chemical reactions (Kishbaugh & Gribble, 2002).

The tertiary butyl group has one methyl group (C18) bisecting the molecular plane with torsion angles of 65.2 (5)° for C1—N2—C17—C18 and -67.5 (5)° for C2—N2—C17—C18. The other two methyl groups, C19 and C20, adopt a gauche butane arrangement with the pyrrolidine methylene groups C3 and C1, respectively.

Related literature top

For the synthesis of the title compound and related chemistry, see: Gribble (2003); Gribble et al. (2005); Roy, Kishbaugh et al. (2007); Kishbaugh & Gribble (2002); Mohanakrishnan & Srinivasan (1995). For a related structure, see: Kishbaugh et al. (2007).

Experimental top

To a refluxing solution of 2,3-dibromomethyl-1-(phenylsulfonyl)indole (294 mg, 0.664 mmol) (Mohanakrishnan & Srinivasan, 1995) and K2CO3 (312 mg, 2.25 mmol) in tetrahydrofuran (10 ml) was added a solution of tert-butylamine (90 µL, 0.80 mmol) in tetrahydrofuran (15 ml) slowly via addition funnel. After 10 h, the reaction mixture was cooled to rt, and the opaque solution was filtered through a Celite pad with ethyl acetate rinses. The resulting combined yellow solution was concentrated in vacuo to yield a pale yellow solid which was purified by column chromatography (2:1 hexanes: ethyl acetate) to yield (I) as a white solid (161 mg, 68%): m.p. 457–458 K. As (I) was unstable toward oxidation, an elemental analysis was not attempted. Recrystallization from hexane–dichloromethane (3:1) yielded crystals that were suitable for X-ray crystallography.

Refinement top

The H atoms were included in the riding model approximation with C—H = 0.93–0.97 Å, and with Uiso(H) = 1.19–1.20Ueq(C).

Structure description top

The title compound, C20H22N2O2S, was synthesized as a precursor to the corresponding pyrrolo[3,4-b]indole as a stable synthetic analogue of indole-2,3-quinodimethane. The tert-butyl group was chosen to block oxidation of the pyrrolidine ring by adventitious oxygen, a side-reaction that is more pronounced with the isopropyl analogue discussed in the preceding paper (Kishbaugh et al., 2007). The X-ray crystallographic analysis confirms the molecular structure and atom connectivity for (I) that we had proposed for this compound based on NMR spectroscopy and chemical reactions (Kishbaugh & Gribble, 2002).

The tertiary butyl group has one methyl group (C18) bisecting the molecular plane with torsion angles of 65.2 (5)° for C1—N2—C17—C18 and -67.5 (5)° for C2—N2—C17—C18. The other two methyl groups, C19 and C20, adopt a gauche butane arrangement with the pyrrolidine methylene groups C3 and C1, respectively.

For the synthesis of the title compound and related chemistry, see: Gribble (2003); Gribble et al. (2005); Roy, Kishbaugh et al. (2007); Kishbaugh & Gribble (2002); Mohanakrishnan & Srinivasan (1995). For a related structure, see: Kishbaugh et al. (2007).

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: CrystalStructure (Rigaku/MSC, 2005); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: CrystalStructure.

Figures top
[Figure 1] Fig. 1. Molecular structure of (I) showing atom labelling and 50% probability displacement ellipsoids.
2-tert-Butyl-4-(phenylsulfonyl)-1,2,3,4-tetrahydropyrrolo[3,4-b]indole top
Crystal data top
C20H22N2O2SDx = 1.326 Mg m3
Mr = 354.46Mo Kα radiation, λ = 0.71069 Å
Orthorhombic, PbcaCell parameters from 20 reflections
a = 18.113 (5) Åθ = 10.4–13.2°
b = 16.140 (9) ŵ = 0.20 mm1
c = 12.146 (8) ÅT = 296 K
V = 3551 (3) Å3Prism, yellow
Z = 80.50 × 0.50 × 0.40 mm
F(000) = 1504
Data collection top
Rigaku AFC-6S
diffractometer
1736 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tubeRint = 0.000
Graphite monochromatorθmax = 27.5°, θmin = 2.3°
ω/2θ scansh = 023
Absorption correction: ψ scan
(North et al., 1968)
k = 020
Tmin = 0.907, Tmax = 0.925l = 150
4059 measured reflections3 standard reflections every 150 reflections
4059 independent reflections intensity decay: none
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.062H-atom parameters constrained
wR(F2) = 0.283 w = 1/[σ2(Fo2) + (0.1437P)2 + 2.0864P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max < 0.001
4059 reflectionsΔρmax = 0.38 e Å3
228 parametersΔρmin = 0.41 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0011 (9)
Crystal data top
C20H22N2O2SV = 3551 (3) Å3
Mr = 354.46Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 18.113 (5) ŵ = 0.20 mm1
b = 16.140 (9) ÅT = 296 K
c = 12.146 (8) Å0.50 × 0.50 × 0.40 mm
Data collection top
Rigaku AFC-6S
diffractometer
1736 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.000
Tmin = 0.907, Tmax = 0.9253 standard reflections every 150 reflections
4059 measured reflections intensity decay: none
4059 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0620 restraints
wR(F2) = 0.283H-atom parameters constrained
S = 1.06Δρmax = 0.38 e Å3
4059 reflectionsΔρmin = 0.41 e Å3
228 parameters
Special details top

Experimental. 1H (CD2Cl2) δ 7.98 (dd, 1H, 1, 7 Hz), 7.83-7.87 (m, 2H), 7.43-7.58 (m, 3H), 7.19-7.35 (m, 3H), 4.30 (m, 2H), 3.96 (m, 2H), 1.18 (s, 9H); 13C (CDCl3) δ 139.7, 138.5, 134.0, 129.6, 128.9, 126.9, 126.1, 123.9, 123.8, 122.9, 119.4, 114.3, 54.1, 48.8, 46.7, 26.3; IR (film) λmax 3061, 2962, 1447, 1364, 1216, 1171, 1089, 995, 913, 748, 720, 682 cm-1; UV (EtOH) λmax 258 nm.

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
S10.25733 (7)0.01040 (8)0.61347 (10)0.0343 (4)
O10.21803 (19)0.0451 (2)0.5441 (3)0.0461 (10)
O20.2272 (2)0.0358 (3)0.7161 (3)0.0517 (11)
N10.3376 (2)0.0366 (3)0.6408 (3)0.0347 (10)
N20.4291 (2)0.1561 (2)0.4210 (3)0.0325 (10)
C10.3561 (3)0.1342 (3)0.4654 (4)0.0386 (13)
H50.32640.10500.41150.046*
H60.32950.18280.49070.046*
C20.4876 (3)0.1369 (3)0.5033 (4)0.0380 (12)
H70.50450.18660.54050.046*
H80.52950.10960.46920.046*
C30.4484 (3)0.0802 (3)0.5810 (4)0.0313 (11)
C40.4609 (3)0.0343 (3)0.6813 (4)0.0327 (12)
C50.5234 (3)0.0151 (3)0.7450 (5)0.0408 (13)
H10.57030.03110.72220.049*
C60.5136 (4)0.0279 (4)0.8423 (5)0.0486 (15)
H30.55450.03990.88590.058*
C70.4448 (3)0.0533 (4)0.8758 (4)0.0453 (14)
H40.44000.08230.94160.054*
C80.3825 (3)0.0368 (3)0.8138 (4)0.0402 (13)
H20.33620.05440.83710.048*
C90.3908 (3)0.0064 (3)0.7163 (4)0.0318 (11)
C100.3770 (3)0.0794 (3)0.5584 (4)0.0310 (11)
C110.2819 (3)0.0994 (3)0.5378 (4)0.0335 (12)
C120.2947 (3)0.0918 (4)0.4257 (5)0.0465 (14)
H90.28840.04120.39040.056*
C130.3169 (4)0.1611 (4)0.3675 (6)0.0621 (19)
H100.32670.15650.29250.075*
C140.3247 (4)0.2362 (4)0.4185 (7)0.065 (2)
H110.33950.28230.37830.078*
C150.3106 (4)0.2435 (4)0.5302 (7)0.0639 (19)
H120.31550.29460.56480.077*
C160.2893 (3)0.1747 (4)0.5906 (5)0.0474 (15)
H130.28000.17920.66570.057*
C170.4340 (3)0.2364 (3)0.3643 (4)0.0362 (12)
C180.4207 (4)0.3109 (3)0.4420 (5)0.0521 (15)
H140.36900.32390.44340.062*
H150.44790.35800.41580.062*
H160.43700.29700.51490.062*
C190.5108 (3)0.2429 (4)0.3128 (6)0.0565 (17)
H170.54420.26760.36460.068*
H180.50830.27660.24780.068*
H190.52810.18860.29350.068*
C200.3769 (3)0.2372 (4)0.2715 (5)0.0551 (17)
H200.39900.21630.20520.066*
H210.36020.29290.25950.066*
H220.33570.20290.29150.066*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0316 (7)0.0367 (7)0.0347 (7)0.0061 (5)0.0014 (6)0.0008 (6)
O10.037 (2)0.044 (2)0.058 (2)0.0048 (17)0.0071 (19)0.0025 (19)
O20.048 (2)0.064 (3)0.042 (2)0.016 (2)0.0144 (19)0.003 (2)
N10.039 (2)0.035 (2)0.031 (2)0.0063 (19)0.0016 (19)0.0039 (18)
N20.037 (2)0.032 (2)0.028 (2)0.0021 (18)0.0027 (18)0.0041 (18)
C10.043 (3)0.037 (3)0.037 (3)0.007 (2)0.008 (2)0.007 (2)
C20.038 (3)0.038 (3)0.038 (3)0.002 (2)0.004 (2)0.002 (2)
C30.036 (3)0.028 (3)0.030 (3)0.002 (2)0.003 (2)0.002 (2)
C40.044 (3)0.025 (2)0.030 (3)0.002 (2)0.004 (2)0.004 (2)
C50.035 (3)0.042 (3)0.045 (3)0.004 (2)0.002 (3)0.001 (3)
C60.060 (4)0.045 (4)0.041 (3)0.007 (3)0.015 (3)0.004 (3)
C70.063 (4)0.045 (3)0.029 (3)0.005 (3)0.005 (3)0.011 (3)
C80.050 (3)0.037 (3)0.033 (3)0.007 (3)0.004 (3)0.001 (2)
C90.039 (3)0.026 (2)0.030 (3)0.003 (2)0.001 (2)0.004 (2)
C100.034 (3)0.026 (2)0.033 (3)0.007 (2)0.004 (2)0.003 (2)
C110.028 (3)0.035 (3)0.037 (3)0.006 (2)0.001 (2)0.002 (2)
C120.054 (4)0.043 (3)0.043 (3)0.006 (3)0.005 (3)0.000 (3)
C130.067 (4)0.067 (5)0.052 (4)0.009 (4)0.014 (3)0.021 (3)
C140.054 (4)0.052 (4)0.091 (6)0.002 (3)0.006 (4)0.025 (4)
C150.056 (4)0.042 (4)0.094 (6)0.006 (3)0.025 (4)0.002 (4)
C160.043 (3)0.046 (3)0.054 (4)0.010 (3)0.009 (3)0.012 (3)
C170.045 (3)0.033 (3)0.030 (3)0.001 (2)0.004 (2)0.008 (2)
C180.066 (4)0.036 (3)0.054 (4)0.004 (3)0.004 (3)0.001 (3)
C190.051 (4)0.062 (4)0.056 (4)0.006 (3)0.006 (3)0.020 (3)
C200.061 (4)0.055 (4)0.050 (4)0.006 (3)0.007 (3)0.023 (3)
Geometric parameters (Å, º) top
S1—O11.421 (4)C8—C91.383 (7)
S1—O21.422 (4)C8—H20.9300
S1—N11.673 (4)C11—C161.380 (7)
S1—C111.762 (5)C11—C121.387 (7)
N1—C101.411 (6)C12—C131.382 (8)
N1—C91.417 (6)C12—H90.9300
N2—C171.470 (6)C13—C141.370 (10)
N2—C11.472 (6)C13—H100.9300
N2—C21.490 (7)C14—C151.386 (10)
C1—C101.483 (7)C14—H110.9300
C1—H50.9700C15—C161.386 (9)
C1—H60.9700C15—H120.9300
C2—C31.494 (7)C16—H130.9300
C2—H70.9700C17—C191.528 (8)
C2—H80.9700C17—C201.530 (7)
C3—C101.322 (6)C17—C181.548 (7)
C3—C41.443 (7)C18—H140.9600
C4—C51.406 (7)C18—H150.9600
C4—C91.412 (7)C18—H160.9600
C5—C61.382 (8)C19—H170.9600
C5—H10.9300C19—H180.9600
C6—C71.374 (8)C19—H190.9600
C6—H30.9300C20—H200.9600
C7—C81.382 (8)C20—H210.9600
C7—H40.9300C20—H220.9600
O1—S1—O2120.7 (3)C3—C10—N1110.6 (4)
O1—S1—N1105.5 (2)C3—C10—C1113.7 (4)
O2—S1—N1106.9 (2)N1—C10—C1134.7 (4)
O1—S1—C11109.3 (2)C16—C11—C12121.2 (5)
O2—S1—C11108.6 (3)C16—C11—S1120.0 (4)
N1—S1—C11104.7 (2)C12—C11—S1118.8 (4)
C10—N1—C9106.4 (4)C13—C12—C11118.7 (6)
C10—N1—S1121.4 (3)C13—C12—H9120.7
C9—N1—S1124.4 (3)C11—C12—H9120.7
C17—N2—C1116.0 (4)C14—C13—C12120.9 (6)
C17—N2—C2117.1 (4)C14—C13—H10119.5
C1—N2—C2110.0 (4)C12—C13—H10119.5
N2—C1—C10101.1 (4)C13—C14—C15120.0 (7)
N2—C1—H5111.5C13—C14—H11120.0
C10—C1—H5111.5C15—C14—H11120.0
N2—C1—H6111.5C14—C15—C16120.1 (6)
C10—C1—H6111.5C14—C15—H12120.0
H5—C1—H6109.4C16—C15—H12120.0
N2—C2—C3102.3 (4)C11—C16—C15119.1 (6)
N2—C2—H7111.3C11—C16—H13120.4
C3—C2—H7111.3C15—C16—H13120.4
N2—C2—H8111.3N2—C17—C19107.9 (4)
C3—C2—H8111.3N2—C17—C20108.2 (4)
H7—C2—H8109.2C19—C17—C20108.3 (5)
C10—C3—C4108.9 (4)N2—C17—C18112.9 (4)
C10—C3—C2109.9 (4)C19—C17—C18109.7 (5)
C4—C3—C2140.6 (5)C20—C17—C18109.7 (5)
C5—C4—C9119.1 (5)C17—C18—H14109.5
C5—C4—C3134.7 (5)C17—C18—H15109.5
C9—C4—C3106.1 (4)H14—C18—H15109.5
C6—C5—C4118.6 (5)C17—C18—H16109.5
C6—C5—H1120.7H14—C18—H16109.5
C4—C5—H1120.7H15—C18—H16109.5
C7—C6—C5121.3 (5)C17—C19—H17109.5
C7—C6—H3119.4C17—C19—H18109.5
C5—C6—H3119.4H17—C19—H18109.5
C6—C7—C8121.5 (5)C17—C19—H19109.5
C6—C7—H4119.3H17—C19—H19109.5
C8—C7—H4119.3H18—C19—H19109.5
C7—C8—C9118.3 (5)C17—C20—H20109.5
C7—C8—H2120.8C17—C20—H21109.5
C9—C8—H2120.8H20—C20—H21109.5
C8—C9—C4121.2 (5)C17—C20—H22109.5
C8—C9—N1130.8 (5)H20—C20—H22109.5
C4—C9—N1107.9 (4)H21—C20—H22109.5

Experimental details

Crystal data
Chemical formulaC20H22N2O2S
Mr354.46
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)296
a, b, c (Å)18.113 (5), 16.140 (9), 12.146 (8)
V3)3551 (3)
Z8
Radiation typeMo Kα
µ (mm1)0.20
Crystal size (mm)0.50 × 0.50 × 0.40
Data collection
DiffractometerRigaku AFC-6S
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.907, 0.925
No. of measured, independent and
observed [I > 2σ(I)] reflections
4059, 4059, 1736
Rint0.000
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.062, 0.283, 1.06
No. of reflections4059
No. of parameters228
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.38, 0.41

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994), MSC/AFC Diffractometer Control Software, CrystalStructure (Rigaku/MSC, 2005), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), CrystalStructure.

 

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