2,3-Dihydro-1H-pyrrolo­[1,2-a]indole-9-carbonitrile

Lee G Madeley; Andreas Lemmerer; Joseph P Michael

doi:10.1107/S1600536812045345

. 2012 Nov 10;68(Pt 12):o3306. doi: 10.1107/S1600536812045345

2,3-Dihydro-1H-pyrrolo[1,2-a]indole-9-carbonitrile

Lee G Madeley ^a, Andreas Lemmerer ^a, Joseph P Michael ^a,^*

PMCID: PMC3588846 PMID: 23468811

Abstract

The asymmetric unit of the title compound, C₁₂H₁₀N₂, which may serve as a model for mitosenes, contains two independent molecules. The conformation of the five-membered rings in both molecules is envelope, with the central CH₂—CH₂—CH₂ C atom at the flap in each case. In the crystal, they interact by a combination of weak C—H⋯N and π–π interactions [centroid–centroid distances = 3.616 (1) and 3.499 (1) Å] and C—H⋯π contacts.

Related literature

For the synthesis of the title compound by intramolecular Heck reaction of [1-(2-bromophenyl)pyrrolidin-2-ylidene]-acetonitrile, see: Michael et al. (1993 ▶). For an alternative synthesis by cyclization of [2-(2-oxopyrrolidin-1-yl)phenyl]acetonitrile with sodium hydride, see: Verboom et al. (1986 ▶). For background to mitosenes, see: Franck (1978 ▶); Kasai & Kono (1992 ▶).

Experimental

Crystal data

C₁₂H₁₀N₂
M _r = 182.22
Triclinic,
a = 9.1383 (3) Å
b = 9.5340 (3) Å
c = 12.3138 (4) Å
α = 90.794 (2)°
β = 90.528 (2)°
γ = 116.272 (2)°
V = 961.78 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 173 K
0.50 × 0.45 × 0.30 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.963, T _max = 0.978
7592 measured reflections
3498 independent reflections
2809 reflections with I > 2σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.038
wR(F ²) = 0.097
S = 1.04
3498 reflections
254 parameters
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-Plus (Bruker, 2004 ▶); data reduction: SAINT-Plus and XPREP (Bruker 2004 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Click here for additional data file.^{(26.9KB, cif)}

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812045345/bh2462sup1.cif

e-68-o3306-sup1.cif^{(26.9KB, cif)}

Click here for additional data file.^{(1.4KB, mol)}

Supplementary material file. DOI: 10.1107/S1600536812045345/bh2462Isup2.mol

Click here for additional data file.^{(168KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812045345/bh2462Isup3.hkl

e-68-o3306-Isup3.hkl^{(168KB, hkl)}

Click here for additional data file.^{(3.9KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536812045345/bh2462Isup4.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 and Cg2 are the centroids of the C6A–C11A and C6B–C11B rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1A—H1A1⋯N2B	0.99	2.68	3.338 (2)	124
C2A—H2A1⋯N2B	0.99	2.66	3.373 (2)	129
C3A—H3A2⋯N2A ⁱ	0.99	2.66	3.634 (2)	168
C3B—H3B1⋯N2B ⁱⁱ	0.99	2.57	3.495 (2)	156
C3A—H3A1⋯Cg1ⁱⁱⁱ	0.99	2.79	3.545 (2)	135
C3B—H3B2⋯Cg2^iv	0.99	2.67	3.523 (2)	146

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

This work was supported by the University of the Witwatersrand and the Molecular Sciences Institute, which are thanked for providing the infrastructure required to do this work. Ms C. Wilson is thanked for carrying out the preliminary synthesis.

supplementary crystallographic information

Comment

The mitosenes, naturally occurring biologically active degradation products of the important mitomycin antibiotics (Franck, 1978; Kasai & Kono, 1992) are characterized by the presence of a pyrrolo[1,2-a]indole core. The title compound, 2,3-dihydro-1H-pyrrolo[1,2-a]indole-9-carbonitrile, was prepared as part of a model study on the use of intramolecular Heck reactions for creating this core from various [1-(2-bromoaryl)pyrrolidin-2-ylidene]acetates and analogues (Michael et al., 1993).

The asymmetric unit of (I) consists of two molecules, labelled A and B, on general positions. Fig. 1 shows the atomic numbering scheme. The hydrogen bonding of (I) consists of weak C—H···N hydrogen bonds and various π–π interactions. Each molecule in the asymmetric unit makes centrosymmetric dimers using the C3A—H3A2···N2A and C3B—H3B1···N2B hydrogen bonds, shown explicitly for the B molecule in Fig. 2. Between the A and B molecules, two ethylene groups from the A molecule hydrogen bond to the cyanide N atom of the B molecule, through C1A—H1A1···N2B and C2A—H2A1···N2B hydrogen bonds. In addition, both A/A and B/B molecules sit parallel to each other and undergo π–π interactions, with distances of 3.616 (1) Å for A···A and 3.499 (1) Å for B···B (Fig. 2). Also C—H···π contacts are formed between those same A/A and B/B molecules, C3A—H3A1···Cg1ⁱⁱⁱ [Cg1: C6A to C11A; symmetry operator: (iii) -x, -y, -z] and C3B—H3B2···Cg2^iv [Cg2: C6B to C11B; symmetry operator: (iv) 1-x, 1-y, 1-z].

Experimental

The title compound was prepared by reaction of [1-(2-bromophenyl)pyrrolidin-2-ylidene]acetonitrile (350 mg, 1.33 mmol) with palladium(II) acetate (299 mg, 1.33 mmol, 1 eq.), tri-o-tolylphosphine (407 mg, 1.33 mmol) and triethylamine (0.19 ml, 1.33 mmol), heated under reflux in acetonitrile (7 ml) for 96 h. The crude oil obtained after evaporation of the solvent (1.20 g) was purified by column chromatography on silica gel with hexane/ethyl acetate (5:1 v/v) as eluent to yield a colourless solid (133 mg, 55%). Recrystallization from ethyl acetate produced colourless blocks, m.p. 400–401 K. An alternative synthesis is available from the literature, based on cyclization of [2-(2-oxopyrrolidin-1-yl)phenyl]acetonitrile with sodium hydride (Verboom et al., 1986).