organic compounds
4-Phenylsulfonyl-2-(p-tolylsulfonyl)-1H,8H-pyrrolo[2,3-b]indole
aDepartment of Biological and Chemical Sciences, University of the West Indies, Cave Hill, Barbados, bDepartment of Chemistry, Dartmouth College, Hanover, NH 03755-3564, USA, and cDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA
*Correspondence e-mail: jjasinski@keene.edu
The title compound, C23H18N2O4S2, contains a pyrrolo group fused onto the plane of an indole ring with phenylsulfonyl and p-toluenesulfonyl groups bonded to the indole and pyrrolo rings. The angles between the mean planes of the pyrrolo-indole ring and the phenylsulfonyl and p-toluenesulfonyl rings are 73.7 (6) and 80.6 (0)°, respectively. The dihedral angle between the mean planes of the two benzene rings is 78.7 (4)°. In the crystal, both classical N—H⋯O and non-classical C—H⋯O intermolecular hydrogen-bonding interactions are observed, as well as weak π–π interactions [centroid–centroid distances = 3.6258 (8) and 3.9298 (8) Å], which contribute to the stability of the packing.
Related literature
We have been interested in the synthesis of fused indole heterocycles (Gribble et al., 2005) for the construction of more elaborate molecules, such as the potent antibiotics pyrroindomycins A and B (Abbanat et al., 1999; Ding et al., 1994) Both pyrrolo[2,3-b]indoles and pyrrolo[3,4-b]indoles can be synthesized in one step via the Barton–Zard pyrrole synthesis (Barton & Zard, 1985; Barton et al., 1990) from 3-nitroindoles, depending on the N-indole protecting group [Pelkey et al., 1996; Pelkey & Gribble, 1997, 1999, 2006). For recent examples of the Barton–Zard pyrrole synthesis, see: Bobal & Lightner (2001); Woydziak et al. (2005); Larionov & deMeijere (2005); Coffin et al. (2006); Okujima et al. (2006); Ono (2008). For related structures, see: Jackson et al. (1975); Moody & Ward (1984a,b); Yamane et al. (1986); Yin et al. (2010); Tsuji et al. (2002); Somei et al. (1997); Kawasaki et al. (2005); Jasinski et al. (2010). For MOPAC theoretical calculations, see: Schmidt & Polik (2007). For standard bond lengths, see: Allen et al. (1987)
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell CrysAlis PRO; data reduction: CrysAlis RED (Oxford Diffraction, 2007); 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: SHELXTL.
Supporting information
https://doi.org/10.1107/S1600536810039425/fl2319sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810039425/fl2319Isup2.hkl
This compound was prepared according to the procedure of Pelkey & Gribble (2006). To a stirred solution of 3-nitro-1-(phenylsulfonyl)indole (0.50 g, 1.67 mmol, 1 eq.) in dry THF (30 ml) was added a solution of tosylmethyl isocyanide (0.39 g, 1.99 mmol, 1.20 eq.) dissolved in dry THF (15 ml) followed by the addition of DBU (0.6 ml, 4.01 mmol, 2.4 eq.). The solution was allowed to stir for 24 h at room temperature. Removal of the solvent in vacuo gave an orange oil that was purified via flash
(3:1 hexanes–ethyl acetate) to afford the pyrroloindole (0.46 g, 62%) as a yellow solid. Crystals suitable for the X-ray study were grown from a 1:1 mixture of CH2Cl2 and ether [m.p. 484–487 K; literature value 509–511 K].All the H atoms were discernible in the difference
however, they were situated into idealized positions. The parameters of all the H atoms have been constrained within the riding atom approximation. C—H bond lengths were constrained to 0.95 or 0.98 Å for aryl or methyl H atoms, and 0.88 for N—H atoms, Uiso(H) = 1.17–1.22Ueq(Caryl); Uiso(H) = 1.51Ueq(Cmethyl) or Uiso(H) = 1.16Ueq(N).In view of our continued interest in the synthesis of fused indole heterocycles (Gribble et al., 2005) for the construction of more elaborate molecules, such as the potent antibiotics pyrroindomycins A and B (Abbanat et al., 1999; Ding et al., 1994), we have sought to unequivocally confirm the assigned structure of the product formed in the reaction of 3-nitro-1-(phenylsulfonyl)indole with isocyanide. Our previous studies have shown that both pyrrolo[2,3-b]indoles and pyrrolo[3,4-b]indoles can be synthesized in one step via this Barton-Zard pyrrole synthesis (Barton & Zard, 1985; Barton et al., 1990) from 3-nitroindoles depending on the N-indole protecting group (Pelkey et al., 1996; Pelkey & Gribble, 1997, 1999, 2006). Indeed, whereas our proposed fragmentation-rearrangement sequence, to afford the pyrrolo[2,3-b]indole ring system (Pelkey et al., 1996), only occurs with the phenylsulfonyl protecting group, the same reaction with N-benzyl, N-2-pyridyl, and N-ethoxycarbonyl protecting groups generates the corresponding pyrrolo[3,4-b]indole ring system. We differentiated these two isomers both by comparison of the NMR coupling constants and through the independent synthesis of the corresponding pyrrolo[2,3-b]indole. (Moody & Ward, 1984a, 1984b). To confirm this structural assignment we now report the
of the title compound, the product of the reaction of 3-nitro-1-(phenylsulfonyl)indole with tosylmethyl isocyanide, and the first of this fused indole ring system.The title compound contains a pyrrolo group fused onto the plane of an indole ring with phenylsulfonyl and p-toluenesulfonyl groups bonded to the indol and pyrrolo rings. The angles between the mean planes of the pyrrolo-indole ring and the phenylsulfonyl and p-toluenesulfonyl rings are 73.7 (6)° and 80.6 (0)°, respectively. The dihedral angle between the mean planes of the two benzene rings is 78.7 (4)°. The sum of the angles around the indole N atom is 345.2 (4)° indicating slightly distorted sp2 ═C10 indole bond length is 1.3760 (17)Å similar to that observed in 3-acetyl-2-ethyl-1-(phenylsulfonyl)indole (Jasinski et al., 2010). The remainder of the bonds are in normal ranges (Allen et al., 1987). Both classical (N—H···O) and non-classical (C—H···O) hydrogen bonding interactions are observed (Table 1, Fig. 2) as well as weak π—π interactions [Cg1···Cg3i = 3.6258 (8) Å; Cg2···Cg3i = 3.9298 (8) Å; i = -x,1 - y,1 - z; where Cg1 = N1/C9/C4/C3/C10; Cg2 = N2/C1/C2/C3/C10; Cg3 = C4—C9].
The C3Following geometry optimization MOPAC (Schmidt & Polik, 2007) theoretical calculations at the AM1 level, the angles between the mean planes of the pyrrolo-indole ring and the phenylsulfonyl and p-toluenesulfonyl rings become 73.7 (6)° and 80.6 (0)°, respectively, and the dihedral angle between the mean planes of the two benzene rings becomes 88.6 (2)°. These observations support the influence of the hydrogen bonds and π—π interactions as contributing to the stability of crystal packing.
We have been interested in the synthesis of fused indole heterocycles (Gribble et al., 2005) for the construction of more elaborate molecules, such as the potent antibiotics pyrroindomycins A and B (Abbanat et al., 1999; Ding et al., 1994) Both pyrrolo[2,3-b]indoles and pyrrolo[3,4-b]indoles can be synthesized in one step via th Barton–Zard pyrrole synthesis (Barton & Zard, 1985; Barton et al., 1990) from 3-nitroindoles depending on the N-indole protecting group [Pelkey et al., 1996; Pelkey & Gribble, 1997, 1999, 2006). For recent examples of the Barton–Zard pyrrole synthesis, see: Bobal & Lightner (2001); Woydziak et al. (2005); Larionov & deMeijere (2005); Coffin et al. (2006); Okujima et al. (2006); Ono (2008). For related structures, see: Jackson et al. (1975); Moody & Ward (1984a,b); Yamane et al. (1986); Yin et al. (2010); Tsuji et al. (2002); Somei et al. (1997); Kawasaki et al. (2005); Jasinski et al. (2010). For MOPAC theoretical calculations, see: Schmidt & Polik (2007). For standard bond lengths, see: Allen et al. (1987 987)
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell
CrysAlis PRO (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); 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: SHELXTL (Sheldrick, 2008).C23H18N2O4S2 | Z = 2 |
Mr = 450.51 | F(000) = 468 |
Triclinic, P1 | Dx = 1.502 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.1547 (3) Å | Cell parameters from 7126 reflections |
b = 11.0471 (5) Å | θ = 5.0–32.7° |
c = 11.7185 (4) Å | µ = 0.30 mm−1 |
α = 73.834 (4)° | T = 123 K |
β = 87.131 (3)° | Prism, colorless |
γ = 79.277 (4)° | 0.41 × 0.36 × 0.29 mm |
V = 996.22 (7) Å3 |
Oxford Diffraction Xcalibur diffractometer with Ruby (Gemini) detector | 6592 independent reflections |
Radiation source: Enhance (Cu) X-ray Source | 5331 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.020 |
Detector resolution: 10.5081 pixels mm-1 | θmax = 32.8°, θmin = 5.1° |
ω scans | h = −11→11 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | k = −16→16 |
Tmin = 0.981, Tmax = 1.000 | l = −17→13 |
12580 measured reflections |
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)] = 0.036 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.103 | H-atom parameters constrained |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0572P)2 + 0.0394P] where P = (Fo2 + 2Fc2)/3 |
6592 reflections | (Δ/σ)max < 0.001 |
281 parameters | Δρmax = 0.52 e Å−3 |
0 restraints | Δρmin = −0.33 e Å−3 |
C23H18N2O4S2 | γ = 79.277 (4)° |
Mr = 450.51 | V = 996.22 (7) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.1547 (3) Å | Mo Kα radiation |
b = 11.0471 (5) Å | µ = 0.30 mm−1 |
c = 11.7185 (4) Å | T = 123 K |
α = 73.834 (4)° | 0.41 × 0.36 × 0.29 mm |
β = 87.131 (3)° |
Oxford Diffraction Xcalibur diffractometer with Ruby (Gemini) detector | 6592 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | 5331 reflections with I > 2σ(I) |
Tmin = 0.981, Tmax = 1.000 | Rint = 0.020 |
12580 measured reflections |
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.103 | H-atom parameters constrained |
S = 1.09 | Δρmax = 0.52 e Å−3 |
6592 reflections | Δρmin = −0.33 e Å−3 |
281 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 | ||
S1 | 0.24124 (3) | 0.40940 (3) | 0.21069 (3) | 0.01455 (7) | |
S2 | 0.53714 (4) | 0.07067 (3) | 0.67939 (3) | 0.01540 (7) | |
O1 | 0.28990 (11) | 0.27445 (8) | 0.22946 (8) | 0.01961 (18) | |
O2 | 0.10331 (10) | 0.48046 (9) | 0.13513 (8) | 0.01992 (19) | |
O3 | 0.61740 (11) | −0.00088 (8) | 0.59944 (8) | 0.02005 (19) | |
O4 | 0.63277 (11) | 0.09255 (9) | 0.76857 (8) | 0.02102 (19) | |
N1 | 0.19171 (12) | 0.42667 (9) | 0.34605 (9) | 0.01529 (19) | |
N2 | 0.36818 (12) | 0.22963 (9) | 0.48254 (9) | 0.01541 (19) | |
H2B | 0.3722 | 0.1694 | 0.4462 | 0.018* | |
C1 | 0.43829 (15) | 0.21752 (11) | 0.59259 (10) | 0.0155 (2) | |
C2 | 0.40399 (15) | 0.33305 (11) | 0.62081 (11) | 0.0169 (2) | |
H2A | 0.4367 | 0.3501 | 0.6906 | 0.020* | |
C3 | 0.30982 (15) | 0.42085 (11) | 0.52414 (11) | 0.0160 (2) | |
C4 | 0.21746 (15) | 0.55003 (11) | 0.47483 (11) | 0.0161 (2) | |
C5 | 0.18616 (17) | 0.66151 (12) | 0.51200 (12) | 0.0218 (3) | |
H5A | 0.2306 | 0.6628 | 0.5850 | 0.026* | |
C6 | 0.08910 (17) | 0.77060 (12) | 0.44084 (12) | 0.0242 (3) | |
H6A | 0.0680 | 0.8471 | 0.4653 | 0.029* | |
C7 | 0.02218 (16) | 0.76964 (12) | 0.33428 (12) | 0.0232 (3) | |
H7A | −0.0436 | 0.8457 | 0.2871 | 0.028* | |
C8 | 0.04966 (15) | 0.65990 (12) | 0.29554 (12) | 0.0200 (2) | |
H8A | 0.0027 | 0.6588 | 0.2233 | 0.024* | |
C9 | 0.14851 (14) | 0.55177 (11) | 0.36653 (11) | 0.0159 (2) | |
C10 | 0.29295 (14) | 0.35350 (11) | 0.44405 (10) | 0.0146 (2) | |
C11 | 0.41636 (14) | 0.48258 (11) | 0.16669 (10) | 0.0142 (2) | |
C12 | 0.57366 (15) | 0.40983 (12) | 0.20143 (11) | 0.0186 (2) | |
H12A | 0.5850 | 0.3233 | 0.2480 | 0.022* | |
C13 | 0.71326 (15) | 0.46588 (13) | 0.16684 (12) | 0.0214 (3) | |
H13A | 0.8213 | 0.4177 | 0.1901 | 0.026* | |
C14 | 0.69552 (16) | 0.59186 (13) | 0.09850 (11) | 0.0210 (3) | |
H14A | 0.7918 | 0.6295 | 0.0746 | 0.025* | |
C15 | 0.53830 (17) | 0.66374 (13) | 0.06448 (12) | 0.0214 (3) | |
H15A | 0.5276 | 0.7502 | 0.0176 | 0.026* | |
C16 | 0.39661 (15) | 0.60964 (12) | 0.09882 (11) | 0.0184 (2) | |
H16A | 0.2886 | 0.6584 | 0.0764 | 0.022* | |
C17 | 0.37346 (15) | −0.00606 (11) | 0.75228 (10) | 0.0155 (2) | |
C18 | 0.34028 (16) | −0.00884 (12) | 0.87037 (11) | 0.0188 (2) | |
H18A | 0.4056 | 0.0289 | 0.9110 | 0.023* | |
C19 | 0.21030 (16) | −0.06741 (12) | 0.92891 (11) | 0.0197 (2) | |
H19A | 0.1885 | −0.0706 | 1.0100 | 0.024* | |
C20 | 0.11216 (15) | −0.12121 (11) | 0.86952 (11) | 0.0175 (2) | |
C21 | 0.14575 (16) | −0.11501 (12) | 0.74970 (11) | 0.0188 (2) | |
H21A | 0.0777 | −0.1496 | 0.7080 | 0.023* | |
C22 | 0.27672 (15) | −0.05922 (11) | 0.69078 (11) | 0.0178 (2) | |
H22A | 0.3001 | −0.0573 | 0.6101 | 0.021* | |
C23 | −0.02767 (17) | −0.18520 (13) | 0.93246 (13) | 0.0244 (3) | |
H23A | −0.0415 | −0.1727 | 1.0122 | 0.037* | |
H23B | −0.0010 | −0.2771 | 0.9388 | 0.037* | |
H23C | −0.1315 | −0.1475 | 0.8873 | 0.037* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.01309 (13) | 0.01663 (14) | 0.01399 (14) | −0.00350 (10) | −0.00090 (10) | −0.00358 (10) |
S2 | 0.01639 (14) | 0.01312 (13) | 0.01499 (14) | −0.00131 (10) | 0.00004 (10) | −0.00193 (10) |
O1 | 0.0238 (4) | 0.0173 (4) | 0.0193 (4) | −0.0061 (3) | −0.0006 (3) | −0.0059 (3) |
O2 | 0.0137 (4) | 0.0273 (5) | 0.0173 (4) | −0.0036 (3) | −0.0034 (3) | −0.0031 (4) |
O3 | 0.0205 (4) | 0.0163 (4) | 0.0219 (5) | −0.0005 (3) | 0.0043 (3) | −0.0056 (3) |
O4 | 0.0204 (4) | 0.0218 (4) | 0.0201 (5) | −0.0053 (4) | −0.0037 (3) | −0.0028 (4) |
N1 | 0.0165 (5) | 0.0145 (4) | 0.0133 (5) | −0.0013 (4) | 0.0001 (4) | −0.0022 (4) |
N2 | 0.0189 (5) | 0.0120 (4) | 0.0147 (5) | −0.0012 (4) | −0.0003 (4) | −0.0036 (4) |
C1 | 0.0183 (5) | 0.0139 (5) | 0.0127 (5) | −0.0018 (4) | 0.0003 (4) | −0.0017 (4) |
C2 | 0.0211 (6) | 0.0146 (5) | 0.0143 (5) | −0.0028 (4) | 0.0004 (4) | −0.0030 (4) |
C3 | 0.0187 (5) | 0.0139 (5) | 0.0145 (5) | −0.0024 (4) | 0.0018 (4) | −0.0033 (4) |
C4 | 0.0167 (5) | 0.0141 (5) | 0.0156 (5) | −0.0025 (4) | 0.0029 (4) | −0.0018 (4) |
C5 | 0.0275 (7) | 0.0167 (5) | 0.0203 (6) | −0.0016 (5) | 0.0019 (5) | −0.0054 (5) |
C6 | 0.0270 (7) | 0.0148 (6) | 0.0287 (7) | 0.0000 (5) | 0.0040 (5) | −0.0059 (5) |
C7 | 0.0203 (6) | 0.0169 (6) | 0.0271 (7) | 0.0024 (5) | 0.0020 (5) | −0.0014 (5) |
C8 | 0.0175 (6) | 0.0186 (6) | 0.0201 (6) | 0.0007 (5) | −0.0008 (4) | −0.0014 (5) |
C9 | 0.0149 (5) | 0.0143 (5) | 0.0173 (6) | −0.0019 (4) | 0.0040 (4) | −0.0033 (4) |
C10 | 0.0153 (5) | 0.0134 (5) | 0.0139 (5) | −0.0024 (4) | 0.0013 (4) | −0.0020 (4) |
C11 | 0.0120 (5) | 0.0178 (5) | 0.0134 (5) | −0.0037 (4) | 0.0006 (4) | −0.0046 (4) |
C12 | 0.0160 (5) | 0.0184 (5) | 0.0191 (6) | −0.0007 (4) | −0.0011 (4) | −0.0029 (5) |
C13 | 0.0129 (5) | 0.0288 (7) | 0.0222 (6) | −0.0022 (5) | −0.0004 (4) | −0.0073 (5) |
C14 | 0.0178 (6) | 0.0301 (7) | 0.0187 (6) | −0.0112 (5) | 0.0043 (4) | −0.0085 (5) |
C15 | 0.0253 (6) | 0.0202 (6) | 0.0177 (6) | −0.0073 (5) | 0.0011 (5) | −0.0019 (5) |
C16 | 0.0177 (5) | 0.0188 (5) | 0.0165 (6) | −0.0016 (4) | −0.0013 (4) | −0.0019 (4) |
C17 | 0.0171 (5) | 0.0114 (5) | 0.0153 (5) | −0.0007 (4) | 0.0000 (4) | −0.0006 (4) |
C18 | 0.0227 (6) | 0.0174 (5) | 0.0153 (6) | −0.0035 (5) | −0.0030 (4) | −0.0024 (4) |
C19 | 0.0235 (6) | 0.0200 (6) | 0.0141 (6) | −0.0035 (5) | 0.0010 (4) | −0.0026 (4) |
C20 | 0.0190 (6) | 0.0128 (5) | 0.0184 (6) | −0.0013 (4) | 0.0013 (4) | −0.0018 (4) |
C21 | 0.0226 (6) | 0.0151 (5) | 0.0197 (6) | −0.0041 (4) | −0.0003 (5) | −0.0057 (4) |
C22 | 0.0224 (6) | 0.0148 (5) | 0.0153 (6) | −0.0012 (4) | 0.0018 (4) | −0.0044 (4) |
C23 | 0.0258 (7) | 0.0244 (6) | 0.0241 (7) | −0.0098 (5) | 0.0058 (5) | −0.0062 (5) |
S1—O1 | 1.4263 (9) | C8—H8A | 0.9500 |
S1—O2 | 1.4316 (9) | C11—C16 | 1.3914 (16) |
S1—N1 | 1.6707 (10) | C11—C12 | 1.3941 (16) |
S1—C11 | 1.7557 (12) | C12—C13 | 1.3856 (18) |
S2—O4 | 1.4322 (9) | C12—H12A | 0.9500 |
S2—O3 | 1.4455 (9) | C13—C14 | 1.3839 (19) |
S2—C1 | 1.7300 (12) | C13—H13A | 0.9500 |
S2—C17 | 1.7701 (12) | C14—C15 | 1.3889 (18) |
N1—C10 | 1.4084 (15) | C14—H14A | 0.9500 |
N1—C9 | 1.4446 (15) | C15—C16 | 1.3895 (18) |
N2—C10 | 1.3506 (14) | C15—H15A | 0.9500 |
N2—C1 | 1.3990 (15) | C16—H16A | 0.9500 |
N2—H2B | 0.8800 | C17—C18 | 1.3896 (17) |
C1—C2 | 1.3818 (17) | C17—C22 | 1.3970 (17) |
C2—C3 | 1.4184 (17) | C18—C19 | 1.3958 (17) |
C2—H2A | 0.9500 | C18—H18A | 0.9500 |
C3—C10 | 1.3760 (17) | C19—C20 | 1.3932 (18) |
C3—C4 | 1.4567 (16) | C19—H19A | 0.9500 |
C4—C5 | 1.3937 (18) | C20—C21 | 1.4022 (17) |
C4—C9 | 1.4075 (17) | C20—C23 | 1.5065 (17) |
C5—C6 | 1.3877 (18) | C21—C22 | 1.3897 (17) |
C5—H5A | 0.9500 | C21—H21A | 0.9500 |
C6—C7 | 1.391 (2) | C22—H22A | 0.9500 |
C6—H6A | 0.9500 | C23—H23A | 0.9800 |
C7—C8 | 1.3861 (19) | C23—H23B | 0.9800 |
C7—H7A | 0.9500 | C23—H23C | 0.9800 |
C8—C9 | 1.3871 (16) | ||
O1—S1—O2 | 121.13 (6) | N2—C10—C3 | 111.89 (11) |
O1—S1—N1 | 104.32 (5) | N2—C10—N1 | 134.91 (11) |
O2—S1—N1 | 106.30 (5) | C3—C10—N1 | 112.99 (10) |
O1—S1—C11 | 109.10 (5) | C16—C11—C12 | 121.61 (11) |
O2—S1—C11 | 109.09 (5) | C16—C11—S1 | 120.24 (9) |
N1—S1—C11 | 105.77 (5) | C12—C11—S1 | 118.15 (9) |
O4—S2—O3 | 120.17 (6) | C13—C12—C11 | 118.89 (11) |
O4—S2—C1 | 108.32 (6) | C13—C12—H12A | 120.6 |
O3—S2—C1 | 107.11 (6) | C11—C12—H12A | 120.6 |
O4—S2—C17 | 107.49 (6) | C14—C13—C12 | 120.11 (12) |
O3—S2—C17 | 107.91 (6) | C14—C13—H13A | 119.9 |
C1—S2—C17 | 104.84 (6) | C12—C13—H13A | 119.9 |
C10—N1—C9 | 103.92 (10) | C13—C14—C15 | 120.63 (12) |
C10—N1—S1 | 119.83 (8) | C13—C14—H14A | 119.7 |
C9—N1—S1 | 121.49 (8) | C15—C14—H14A | 119.7 |
C10—N2—C1 | 105.31 (10) | C14—C15—C16 | 120.20 (12) |
C10—N2—H2B | 127.3 | C14—C15—H15A | 119.9 |
C1—N2—H2B | 127.3 | C16—C15—H15A | 119.9 |
C2—C1—N2 | 110.47 (10) | C15—C16—C11 | 118.56 (11) |
C2—C1—S2 | 128.02 (10) | C15—C16—H16A | 120.7 |
N2—C1—S2 | 121.31 (9) | C11—C16—H16A | 120.7 |
C1—C2—C3 | 105.85 (11) | C18—C17—C22 | 120.89 (11) |
C1—C2—H2A | 127.1 | C18—C17—S2 | 118.71 (10) |
C3—C2—H2A | 127.1 | C22—C17—S2 | 120.37 (9) |
C10—C3—C2 | 106.48 (10) | C17—C18—C19 | 119.56 (12) |
C10—C3—C4 | 106.28 (10) | C17—C18—H18A | 120.2 |
C2—C3—C4 | 147.16 (12) | C19—C18—H18A | 120.2 |
C5—C4—C9 | 118.78 (11) | C20—C19—C18 | 120.61 (12) |
C5—C4—C3 | 134.52 (12) | C20—C19—H19A | 119.7 |
C9—C4—C3 | 106.70 (10) | C18—C19—H19A | 119.7 |
C6—C5—C4 | 119.01 (13) | C19—C20—C21 | 118.85 (11) |
C6—C5—H5A | 120.5 | C19—C20—C23 | 120.83 (11) |
C4—C5—H5A | 120.5 | C21—C20—C23 | 120.31 (12) |
C5—C6—C7 | 121.04 (12) | C22—C21—C20 | 121.23 (12) |
C5—C6—H6A | 119.5 | C22—C21—H21A | 119.4 |
C7—C6—H6A | 119.5 | C20—C21—H21A | 119.4 |
C8—C7—C6 | 121.29 (12) | C21—C22—C17 | 118.83 (11) |
C8—C7—H7A | 119.4 | C21—C22—H22A | 120.6 |
C6—C7—H7A | 119.4 | C17—C22—H22A | 120.6 |
C7—C8—C9 | 117.26 (12) | C20—C23—H23A | 109.5 |
C7—C8—H8A | 121.4 | C20—C23—H23B | 109.5 |
C9—C8—H8A | 121.4 | H23A—C23—H23B | 109.5 |
C8—C9—C4 | 122.62 (11) | C20—C23—H23C | 109.5 |
C8—C9—N1 | 127.30 (11) | H23A—C23—H23C | 109.5 |
C4—C9—N1 | 110.05 (10) | H23B—C23—H23C | 109.5 |
O1—S1—N1—C10 | 42.28 (10) | C2—C3—C10—N2 | 0.36 (14) |
O2—S1—N1—C10 | 171.37 (9) | C4—C3—C10—N2 | −177.43 (10) |
C11—S1—N1—C10 | −72.74 (10) | C2—C3—C10—N1 | 175.95 (10) |
O1—S1—N1—C9 | 174.84 (9) | C4—C3—C10—N1 | −1.84 (13) |
O2—S1—N1—C9 | −56.07 (10) | C9—N1—C10—N2 | 176.61 (13) |
C11—S1—N1—C9 | 59.82 (10) | S1—N1—C10—N2 | −43.72 (18) |
C10—N2—C1—C2 | 0.64 (13) | C9—N1—C10—C3 | 2.39 (13) |
C10—N2—C1—S2 | 175.91 (9) | S1—N1—C10—C3 | 142.06 (9) |
O4—S2—C1—C2 | −20.80 (13) | O1—S1—C11—C16 | 154.12 (10) |
O3—S2—C1—C2 | −151.78 (11) | O2—S1—C11—C16 | 19.79 (12) |
C17—S2—C1—C2 | 93.73 (12) | N1—S1—C11—C16 | −94.18 (11) |
O4—S2—C1—N2 | 164.83 (9) | O1—S1—C11—C12 | −25.73 (11) |
O3—S2—C1—N2 | 33.85 (11) | O2—S1—C11—C12 | −160.07 (10) |
C17—S2—C1—N2 | −80.63 (10) | N1—S1—C11—C12 | 85.96 (11) |
N2—C1—C2—C3 | −0.43 (14) | C16—C11—C12—C13 | −0.25 (19) |
S2—C1—C2—C3 | −175.30 (9) | S1—C11—C12—C13 | 179.61 (10) |
C1—C2—C3—C10 | 0.05 (13) | C11—C12—C13—C14 | −0.3 (2) |
C1—C2—C3—C4 | 176.14 (18) | C12—C13—C14—C15 | 0.4 (2) |
C10—C3—C4—C5 | 179.76 (14) | C13—C14—C15—C16 | 0.0 (2) |
C2—C3—C4—C5 | 3.7 (3) | C14—C15—C16—C11 | −0.49 (19) |
C10—C3—C4—C9 | 0.47 (13) | C12—C11—C16—C15 | 0.64 (19) |
C2—C3—C4—C9 | −175.62 (18) | S1—C11—C16—C15 | −179.22 (10) |
C9—C4—C5—C6 | −0.39 (18) | O4—S2—C17—C18 | 12.96 (11) |
C3—C4—C5—C6 | −179.62 (13) | O3—S2—C17—C18 | 143.93 (9) |
C4—C5—C6—C7 | 0.5 (2) | C1—S2—C17—C18 | −102.15 (10) |
C5—C6—C7—C8 | 0.1 (2) | O4—S2—C17—C22 | −168.94 (9) |
C6—C7—C8—C9 | −0.90 (19) | O3—S2—C17—C22 | −37.97 (11) |
C7—C8—C9—C4 | 1.05 (18) | C1—S2—C17—C22 | 75.95 (11) |
C7—C8—C9—N1 | 178.71 (12) | C22—C17—C18—C19 | 1.07 (17) |
C5—C4—C9—C8 | −0.41 (18) | S2—C17—C18—C19 | 179.16 (9) |
C3—C4—C9—C8 | 179.01 (11) | C17—C18—C19—C20 | −1.00 (18) |
C5—C4—C9—N1 | −178.44 (11) | C18—C19—C20—C21 | −0.28 (18) |
C3—C4—C9—N1 | 0.99 (13) | C18—C19—C20—C23 | 179.65 (11) |
C10—N1—C9—C8 | −179.91 (11) | C19—C20—C21—C22 | 1.53 (18) |
S1—N1—C9—C8 | 41.26 (16) | C23—C20—C21—C22 | −178.40 (11) |
C10—N1—C9—C4 | −2.01 (12) | C20—C21—C22—C17 | −1.47 (18) |
S1—N1—C9—C4 | −140.84 (9) | C18—C17—C22—C21 | 0.15 (17) |
C1—N2—C10—C3 | −0.61 (13) | S2—C17—C22—C21 | −177.91 (9) |
C1—N2—C10—N1 | −174.88 (12) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2B···O3i | 0.88 | 2.06 | 2.9244 (14) | 167 |
C13—H13A···O2ii | 0.95 | 2.53 | 3.2125 (15) | 129 |
C22—H22A···O3i | 0.95 | 2.45 | 3.3786 (15) | 165 |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C23H18N2O4S2 |
Mr | 450.51 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 123 |
a, b, c (Å) | 8.1547 (3), 11.0471 (5), 11.7185 (4) |
α, β, γ (°) | 73.834 (4), 87.131 (3), 79.277 (4) |
V (Å3) | 996.22 (7) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.30 |
Crystal size (mm) | 0.41 × 0.36 × 0.29 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur diffractometer with Ruby (Gemini) detector |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2007) |
Tmin, Tmax | 0.981, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12580, 6592, 5331 |
Rint | 0.020 |
(sin θ/λ)max (Å−1) | 0.762 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.103, 1.09 |
No. of reflections | 6592 |
No. of parameters | 281 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.52, −0.33 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2007), CrysAlis RED (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2B···O3i | 0.88 | 2.06 | 2.9244 (14) | 166.7 |
C13—H13A···O2ii | 0.95 | 2.53 | 3.2125 (15) | 129.3 |
C22—H22A···O3i | 0.95 | 2.45 | 3.3786 (15) | 165.0 |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x+1, y, z. |
Acknowledgements
JCB wishes to thank the UWI and the Government of Barbados for funding this research. JPJ thanks Dr Ray Butcher and Howard University for assistance with the data collection and acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase the X-ray diffractometer.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
In view of our continued interest in the synthesis of fused indole heterocycles (Gribble et al., 2005) for the construction of more elaborate molecules, such as the potent antibiotics pyrroindomycins A and B (Abbanat et al., 1999; Ding et al., 1994), we have sought to unequivocally confirm the assigned structure of the product formed in the reaction of 3-nitro-1-(phenylsulfonyl)indole with isocyanide. Our previous studies have shown that both pyrrolo[2,3-b]indoles and pyrrolo[3,4-b]indoles can be synthesized in one step via this Barton-Zard pyrrole synthesis (Barton & Zard, 1985; Barton et al., 1990) from 3-nitroindoles depending on the N-indole protecting group (Pelkey et al., 1996; Pelkey & Gribble, 1997, 1999, 2006). Indeed, whereas our proposed fragmentation-rearrangement sequence, to afford the pyrrolo[2,3-b]indole ring system (Pelkey et al., 1996), only occurs with the phenylsulfonyl protecting group, the same reaction with N-benzyl, N-2-pyridyl, and N-ethoxycarbonyl protecting groups generates the corresponding pyrrolo[3,4-b]indole ring system. We differentiated these two isomers both by comparison of the NMR coupling constants and through the independent synthesis of the corresponding pyrrolo[2,3-b]indole. (Moody & Ward, 1984a, 1984b). To confirm this structural assignment we now report the crystal structure of the title compound, the product of the reaction of 3-nitro-1-(phenylsulfonyl)indole with tosylmethyl isocyanide, and the first crystal structure of this fused indole ring system.
The title compound contains a pyrrolo group fused onto the plane of an indole ring with phenylsulfonyl and p-toluenesulfonyl groups bonded to the indol and pyrrolo rings. The angles between the mean planes of the pyrrolo-indole ring and the phenylsulfonyl and p-toluenesulfonyl rings are 73.7 (6)° and 80.6 (0)°, respectively. The dihedral angle between the mean planes of the two benzene rings is 78.7 (4)°. The sum of the angles around the indole N atom is 345.2 (4)° indicating slightly distorted sp2 hybridization. The C3═C10 indole bond length is 1.3760 (17)Å similar to that observed in 3-acetyl-2-ethyl-1-(phenylsulfonyl)indole (Jasinski et al., 2010). The remainder of the bonds are in normal ranges (Allen et al., 1987). Both classical (N—H···O) and non-classical (C—H···O) hydrogen bonding interactions are observed (Table 1, Fig. 2) as well as weak π—π interactions [Cg1···Cg3i = 3.6258 (8) Å; Cg2···Cg3i = 3.9298 (8) Å; i = -x,1 - y,1 - z; where Cg1 = N1/C9/C4/C3/C10; Cg2 = N2/C1/C2/C3/C10; Cg3 = C4—C9].
Following geometry optimization MOPAC (Schmidt & Polik, 2007) theoretical calculations at the AM1 level, the angles between the mean planes of the pyrrolo-indole ring and the phenylsulfonyl and p-toluenesulfonyl rings become 73.7 (6)° and 80.6 (0)°, respectively, and the dihedral angle between the mean planes of the two benzene rings becomes 88.6 (2)°. These observations support the influence of the hydrogen bonds and π—π interactions as contributing to the stability of crystal packing.