2-Isopropyl-4-(phenyl­sulfon­yl)-1,2,3,4-tetra­hydro­pyrrolo[3,4-b]indole

The indole ring and the pyrrolidine C atoms of the title compound, C₁₉H₁₉N₂O₂S, are essentially coplanar. The angle between the planes of the phenyl­sulfonyl ring and the indole ring system is 88.0 (1)°. The pyrrolidine N atom is disordered over two positions, with a site-occupancy ratio of 3:2, and has bond angles totaling 357.0°, indicating significant flattening from a purely pyramidal N atom, which in ammonia has angles totaling 324°.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.006 Å
• Disorder in main residue
• R factor = 0.054
• wR factor = 0.185
• Data-to-parameter ratio = 17.5

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT351_ALERT_3_B Long    C-H Bond (0.96A)   C2     -   H2B    ...       1.18 Ang.

Alert level C
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         43 Perc.
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT155_ALERT_4_C The Triclinic Unitcell is NOT Reduced ..........          ?
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for        C17
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        C11
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        N2B
PLAT301_ALERT_3_C Main Residue  Disorder .........................       4.00 Perc.
PLAT331_ALERT_2_C Small Average Phenyl C-C Dist.   C11    -C16           1.37 Ang.
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          6

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
  10 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 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

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S1. Comment

The title compound, C₁₉H₁₉N₂O₂S, was synthesized as a precursor to the corresponding pyrrolo[3,4-b]indole as a stable synthetic analogue of indole-2,3-quinodimethane. The X-ray crystallographic analysis, Fig. 1, confirms the molecular structure and atom connectivity that we had proposed for this compound based on NMR spectroscopy and chemical reactions (Kishbaugh & Gribble, 2002).

The three isopropyl carbons lie nearly in the molecular plane with torsion angles of 19.4 (7)° (C1—N2—C17—C18) and -18.1 (7)° (C2—N2—C17—C19), respectively.

Related literature

For synthesis and chemistry see: Gribble (2003); Gribble et al. (2005); Roy, Kishbaugh et al. (2007); Roy, Pelkey et al. (2007); Kishbaugh & Gribble (2002); Mohanakrishnan & Srinivasan (1995).

S2. Experimental

To a 35°C solution of 2,3-dibromomethyl-1-(phenylsulfonyl)indole (470 mg, 1.06 mmol) (Mohanakrishnan & Srinivasan, 1995) and K₂CO₃ (404 mg, 2.90 mmol) in tetrahydrofuran (20 ml) was added a solution of isopropyl amine (100 µL, 1.17 mmol) in tetrahydrofuran (20 ml) slowly via an addition funnel. After 2 h, the opaque solution was filtered through a Celite pad with ethyl acetate rinses. The combined yellow organic solution was concentrated in vacuo to yield (I) as a pale yellow solid. After column chromatography (1:1; ethyl acetate: hexanes), 197 mg of (I) (61%) was isolated as a white solid: m.p. 419–420 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.

S3. Refinement

The H atoms were included in the riding model approximation with C—H = 0.93–0.98 Å, and with U_iso(H) = 1.19–1.20U_eq(C).

Computing details

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

Fig. 1. Molecular structure of (I) showing atom labeling and 50% probability displacement ellipsoids. N2 is disordered with N2a (0.6) and N2b (0.4) at partial occupancy.

2-Isopropyl-4-(phenylsulfonyl)-1,2,3,4-tetrahydropyrrolo[3,4-b]indole

Crystal data

C19H19N2O2S	Z = 2
Mr = 339.42	F(000) = 358
Triclinic, P1	Dx = 1.304 Mg m^−3
a = 8.196 (2) Å	Mo Kα radiation, λ = 0.71069 Å
b = 9.559 (3) Å	Cell parameters from 20 reflections
c = 12.359 (2) Å	θ = 6.4–9.1°
α = 70.801 (19)°	µ = 0.20 mm^−1
β = 98.54 (2)°	T = 296 K
γ = 108.88 (2)°	Prism, colorless
V = 864.2 (4) Å^3	0.40 × 0.30 × 0.20 mm

Data collection

Rigaku AFC-6S diffractometer	1720 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	θmax = 27.5°, θmin = 1.8°
Graphite monochromator	h = −10→10
ω/2θ scans	k = 0→12
Absorption correction: ψ scan (North et al., 1968)	l = −15→16
Tmin = 0.924, Tmax = 0.961	3 standard reflections every 150 reflections
3977 measured reflections	intensity decay: none
3977 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.185	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0843P)^2 + 0.1181P] where P = (Fo^2 + 2Fc^2)/3
3977 reflections	(Δ/σ)max < 0.001
227 parameters	Δρmax = 0.42 e Å^−3
0 restraints	Δρmin = −0.37 e Å^−3

Special details

Experimental. ¹H (CD₂Cl₂) δ 8.00 (m, 1H), 7.87 (m, 2H), 7.51-7.57 (m, 1H), 7.42-7.47 (m, 2H), 7.33-7.37 (m, 2H), 7.20-7.30 (m, 2H), 4.27-4.30 (m, 2H), 3.91-3.94 (m, 2H), 2.96 (septet, 1H, 6 Hz), 1.20 (d, 6H, 6 Hz); ¹³C (CD₂Cl₂) δ 140.5, 139.9, 138.5, 134.3, 129.8, 127.0, 126.4, 124.1, 124.0, 123.9, 119.6, 114.5, 54.5, 52.7, 50.7, 21.3; IR (film) ν_max 2968, 2889, 2789, 1448, 1371, 1179, 996, 748, 726, 685 cm^-1; UV (EtOH) ν_max 260 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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
S1	0.81739 (12)	0.75976 (11)	0.83788 (8)	0.0434 (3)
O1	0.8348 (3)	0.6439 (3)	0.7955 (2)	0.0561 (7)
O2	0.9307 (3)	0.8042 (3)	0.9280 (2)	0.0596 (7)
N1	0.8420 (4)	0.9168 (3)	0.7251 (2)	0.0412 (7)
N2A	0.7365 (11)	0.8952 (11)	0.4282 (8)	0.063 (2)	0.60
N2B	0.6592 (11)	0.8685 (15)	0.4443 (11)	0.033 (2)	0.40
C1	0.7554 (4)	0.7990 (4)	0.5483 (3)	0.0451 (9)
H1A	0.6776	0.6989	0.5859	0.049*
H1B	0.8539	0.7684	0.5482	0.055*
C2	0.7259 (5)	1.0457 (4)	0.4256 (3)	0.0502 (9)
H2A	0.7037	1.1286	0.3588	0.060*
H2B	0.8407	1.1291	0.3666	0.060*
C3	0.7756 (4)	1.0509 (4)	0.5453 (3)	0.0417 (8)
C4	0.8172 (4)	1.1538 (4)	0.6144 (3)	0.0429 (8)
C5	0.8286 (5)	1.3103 (4)	0.5912 (4)	0.0578 (10)
H5	0.8076	1.3702	0.5173	0.069*
C6	0.8719 (5)	1.3728 (5)	0.6813 (4)	0.0631 (11)
H6	0.8796	1.4763	0.6677	0.076*
C7	0.9043 (5)	1.2846 (5)	0.7919 (4)	0.0583 (11)
H7	0.9314	1.3305	0.8505	0.070*
C8	0.8975 (5)	1.1326 (5)	0.8172 (3)	0.0512 (9)
H8	0.9208	1.0748	0.8913	0.061*
C9	0.8541 (4)	1.0679 (4)	0.7267 (3)	0.0405 (8)
C10	0.7886 (4)	0.9137 (4)	0.6119 (3)	0.0392 (8)
C11	0.6027 (4)	0.7119 (4)	0.8750 (3)	0.0393 (8)
C12	0.4712 (5)	0.6450 (5)	0.8095 (4)	0.0611 (11)
H12	0.4946	0.6227	0.7467	0.073*
C13	0.3034 (6)	0.6111 (5)	0.8375 (4)	0.0744 (13)
H13	0.2128	0.5676	0.7923	0.089*
C14	0.2692 (6)	0.6406 (5)	0.9308 (4)	0.0683 (13)
H14	0.1555	0.6172	0.9493	0.082*
C15	0.4016 (6)	0.7045 (6)	0.9973 (4)	0.0770 (13)
H15	0.3780	0.7225	1.0621	0.092*
C16	0.5692 (5)	0.7421 (5)	0.9689 (3)	0.0603 (11)
H16	0.6594	0.7879	1.0131	0.072*
C17	0.6808 (8)	0.8350 (5)	0.3439 (4)	0.0870 (17)
C18	0.6535 (6)	0.6699 (5)	0.3577 (4)	0.0730 (13)
H18A	0.7534	0.6579	0.3342	0.088*
H18B	0.5543	0.6335	0.3113	0.088*
H18C	0.6351	0.6108	0.4368	0.088*
C19	0.6286 (7)	0.9265 (6)	0.2316 (4)	0.0794 (14)
H19A	0.5112	0.9251	0.2324	0.095*
H19B	0.6383	0.8830	0.1739	0.095*
H19C	0.7022	1.0314	0.2149	0.095*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0455 (5)	0.0454 (5)	0.0412 (5)	0.0190 (4)	0.0019 (4)	−0.0101 (4)
O1	0.0730 (18)	0.0496 (15)	0.0576 (16)	0.0339 (13)	0.0099 (13)	−0.0127 (13)
O2	0.0509 (16)	0.0796 (19)	0.0472 (15)	0.0239 (14)	−0.0116 (12)	−0.0188 (14)
N1	0.0462 (17)	0.0377 (16)	0.0416 (16)	0.0109 (13)	0.0040 (13)	−0.0151 (13)
N2A	0.099 (7)	0.047 (5)	0.045 (5)	0.030 (6)	−0.017 (5)	−0.019 (4)
N2B	0.020 (4)	0.039 (5)	0.039 (5)	0.005 (4)	0.011 (4)	−0.012 (4)
C1	0.052 (2)	0.040 (2)	0.047 (2)	0.0133 (17)	0.0038 (17)	−0.0165 (17)
C2	0.063 (2)	0.040 (2)	0.046 (2)	0.0191 (18)	−0.0077 (18)	−0.0122 (17)
C3	0.045 (2)	0.040 (2)	0.044 (2)	0.0174 (16)	−0.0030 (15)	−0.0160 (16)
C4	0.0395 (19)	0.040 (2)	0.055 (2)	0.0141 (15)	0.0028 (16)	−0.0195 (17)
C5	0.056 (2)	0.045 (2)	0.077 (3)	0.0178 (19)	0.002 (2)	−0.022 (2)
C6	0.062 (3)	0.045 (2)	0.093 (3)	0.016 (2)	0.008 (2)	−0.034 (2)
C7	0.056 (2)	0.056 (3)	0.073 (3)	0.003 (2)	0.010 (2)	−0.042 (2)
C8	0.045 (2)	0.057 (3)	0.055 (2)	0.0053 (17)	0.0106 (17)	−0.0275 (19)
C9	0.0345 (18)	0.038 (2)	0.050 (2)	0.0071 (15)	0.0051 (15)	−0.0177 (16)
C10	0.0411 (19)	0.0396 (19)	0.0396 (19)	0.0116 (15)	0.0025 (15)	−0.0152 (16)
C11	0.0395 (19)	0.0364 (18)	0.0380 (18)	0.0127 (15)	0.0036 (15)	−0.0038 (15)
C12	0.053 (2)	0.059 (3)	0.064 (3)	0.001 (2)	0.007 (2)	−0.023 (2)
C13	0.051 (3)	0.069 (3)	0.081 (3)	0.000 (2)	−0.003 (2)	−0.015 (3)
C14	0.049 (3)	0.065 (3)	0.079 (3)	0.023 (2)	0.022 (2)	0.008 (2)
C15	0.064 (3)	0.094 (4)	0.079 (3)	0.026 (3)	0.019 (3)	−0.023 (3)
C16	0.051 (2)	0.076 (3)	0.055 (2)	0.012 (2)	0.0058 (19)	−0.026 (2)
C17	0.157 (5)	0.065 (3)	0.049 (3)	0.040 (3)	−0.008 (3)	−0.028 (2)
C18	0.094 (3)	0.070 (3)	0.069 (3)	0.028 (3)	−0.002 (3)	−0.040 (2)
C19	0.096 (4)	0.089 (3)	0.057 (3)	0.030 (3)	−0.020 (3)	−0.034 (3)

Geometric parameters (Å, º)

S1—O1	1.424 (3)	C6—C7	1.388 (6)
S1—O2	1.425 (3)	C6—H6	0.9300
S1—N1	1.658 (3)	C7—C8	1.366 (5)
S1—C11	1.760 (3)	C7—H7	0.9300
N1—C10	1.410 (4)	C8—C9	1.399 (5)
N1—C9	1.421 (4)	C8—H8	0.9300
N2A—N2B	0.637 (10)	C11—C12	1.364 (5)
N2A—C17	1.307 (10)	C11—C16	1.369 (5)
N2A—C2	1.459 (10)	C12—C13	1.377 (6)
N2A—C1	1.483 (10)	C12—H12	0.9300
N2B—C17	1.427 (13)	C13—C14	1.360 (6)
N2B—C1	1.480 (14)	C13—H13	0.9300
N2B—C2	1.551 (13)	C14—C15	1.365 (6)
C1—C10	1.485 (5)	C14—H14	0.9300
C1—H1A	0.9687	C15—C16	1.371 (6)
C1—H1B	0.9437	C15—H15	0.9300
C2—C3	1.488 (5)	C16—H16	0.9300
C2—H2A	0.9800	C17—C19	1.463 (6)
C2—H2B	1.1780	C17—C18	1.475 (6)
C3—C10	1.328 (5)	C18—H18A	0.9600
C3—C4	1.436 (5)	C18—H18B	0.9600
C4—C5	1.402 (5)	C18—H18C	0.9600
C4—C9	1.406 (5)	C19—H19A	0.9600
C5—C6	1.381 (6)	C19—H19B	0.9600
C5—H5	0.9300	C19—H19C	0.9600
O1—S1—O2	120.78 (17)	C7—C8—H8	121.5
O1—S1—N1	104.87 (15)	C9—C8—H8	121.5
O2—S1—N1	107.01 (16)	C8—C9—C4	122.0 (3)
O1—S1—C11	109.32 (16)	C8—C9—N1	130.1 (3)
O2—S1—C11	108.96 (16)	C4—C9—N1	107.8 (3)
N1—S1—C11	104.66 (15)	C3—C10—N1	111.1 (3)
C10—N1—C9	105.9 (3)	C3—C10—C1	113.0 (3)
C10—N1—S1	124.0 (2)	N1—C10—C1	135.7 (3)
C9—N1—S1	126.0 (2)	C12—C11—C16	120.7 (4)
C17—N2A—C2	123.9 (7)	C12—C11—S1	119.5 (3)
C17—N2A—C1	122.3 (7)	C16—C11—S1	119.8 (3)
C2—N2A—C1	110.3 (6)	C11—C12—C13	119.2 (4)
C17—N2B—C1	114.5 (8)	C11—C12—H12	120.4
C17—N2B—C2	110.1 (8)	C13—C12—H12	120.4
C1—N2B—C2	105.6 (8)	C14—C13—C12	120.4 (4)
N2B—C1—C10	101.1 (6)	C14—C13—H13	119.8
N2A—C1—C10	101.7 (4)	C12—C13—H13	119.8
N2A—C1—H1A	126.4	C13—C14—C15	120.0 (4)
C10—C1—H1A	113.4	C13—C14—H14	120.0
N2B—C1—H1B	124.9	C15—C14—H14	120.0
C10—C1—H1B	112.4	C14—C15—C16	120.1 (4)
N2A—C2—C3	103.9 (4)	C14—C15—H15	119.9
C3—C2—N2B	101.2 (6)	C16—C15—H15	119.9
N2A—C2—H2A	127.9	C11—C16—C15	119.5 (4)
C3—C2—H2A	127.9	C11—C16—H16	120.2
C3—C2—H2B	108.7	C15—C16—H16	120.2
N2B—C2—H2B	123.2	N2A—C17—C19	121.2 (6)
C10—C3—C4	108.2 (3)	N2B—C17—C19	119.2 (7)
C10—C3—C2	109.8 (3)	N2A—C17—C18	122.7 (6)
C4—C3—C2	142.0 (3)	N2B—C17—C18	115.3 (6)
C5—C4—C9	119.3 (3)	C19—C17—C18	115.9 (4)
C5—C4—C3	133.8 (4)	C17—C18—H18A	109.5
C9—C4—C3	106.8 (3)	C17—C18—H18B	109.5
C6—C5—C4	118.0 (4)	H18A—C18—H18B	109.5
C6—C5—H5	121.0	C17—C18—H18C	109.5
C4—C5—H5	121.0	H18A—C18—H18C	109.5
C5—C6—C7	121.5 (4)	H18B—C18—H18C	109.5
C5—C6—H6	119.2	C17—C19—H19A	109.5
C7—C6—H6	119.2	C17—C19—H19B	109.5
C8—C7—C6	122.0 (4)	H19A—C19—H19B	109.5
C8—C7—H7	119.0	C17—C19—H19C	109.5
C6—C7—H7	119.0	H19A—C19—H19C	109.5
C7—C8—C9	117.0 (4)	H19B—C19—H19C	109.5