2-Ethyl-6,6-ethyl­enedisulfanediyl-7-methoxy­methyl-1,2,3,4,5,6-hexa­hydro-1,5-methano­azocino[4,3-b]indol-3-one

Barış Tercan; Ertan Şahin; Süleyman Patır; Tuncer Hökelek

doi:10.1107/S160053681000067X

. 2010 Jan 9;66(Pt 2):o328. doi: 10.1107/S160053681000067X

2-Ethyl-6,6-ethylenedisulfanediyl-7-methoxymethyl-1,2,3,4,5,6-hexahydro-1,5-methanoazocino[4,3-b]indol-3-one

Barış Tercan ^a, Ertan Şahin ^b, Süleyman Patır ^c, Tuncer Hökelek ^d,^*

PMCID: PMC2979738 PMID: 21579758

Abstract

The title compound, C₂₀H₂₄N₂O₂S₂, consists of a tetracyclic ring system containing an azocino skeleton with ethyl, dithiolane and methoxymethyl groups as substituents. The benzene and five-membered rings are nearly coplanar, with a dihedral angle of 2.78 (11)°. The dithiolane ring adopts an envelope conformation. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules into chains nearly parallel to the c axis. Two C—H⋯π interactions are also present.

Related literature

For considerations of the hexahydro-1,5-methanoazocino[4,3-b]indole core structure as a synthetic precursor for most of the pentacyclic and tetracyclic indole alkaloids of biological interest, see: Hesse (2002 ▶); Bosch & Bonjoch (1988 ▶); Saxton (1983 ▶). For related structures, see: Hökelek et al. (2004 ▶, 2006 ▶, 2007 ▶); Uludağ et al. (2006 ▶).

Experimental

Crystal data

C₂₀H₂₄N₂O₂S₂
M _r = 388.53
Monoclinic,
a = 14.0409 (3) Å
b = 6.8916 (2) Å
c = 20.2820 (4) Å
β = 109.783 (2)°
V = 1846.74 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.31 mm⁻¹
T = 294 K
0.35 × 0.25 × 0.20 mm

Data collection

Rigaku R-AXIS RAPID-S diffractometer
Absorption correction: multi-scan (Blessing, 1995 ▶) T _min = 0.910, T _max = 0.941
24759 measured reflections
3794 independent reflections
2746 reflections with I > 2σ(I)
R _int = 0.083

Refinement

R[F ² > 2σ(F ²)] = 0.057
wR(F ²) = 0.161
S = 1.05
3794 reflections
237 parameters
H-atom parameters constrained
Δρ_max = 0.61 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Data collection: CrystalClear (Rigaku/MSC, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; 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 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053681000067X/xu2717sup1.cif

e-66-0o328-sup1.cif^{(22.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681000067X/xu2717Isup2.hkl

e-66-0o328-Isup2.hkl^{(182.2KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C18—H18C⋯O1ⁱ	0.96	2.43	3.365 (5)	165
C11—H11⋯Cg1ⁱⁱ	0.93	2.80	3.569 (4)	141
C16—H16A⋯Cg1ⁱⁱⁱ	0.96	2.66	3.514 (5)	148

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) . Cg1 is the centroid of the C7A/C8–C11/C11A ring.

Acknowledgments

The authors are indebted to the Department of Chemistry, Atatürk University, Erzurum, Turkey, for the use of the X-ray diffractometer purchased under grant No. 2003/219 of the University Research Fund.

supplementary crystallographic information

Comment

The hexahydro-1,5-methano-azocino[4,3-b]indole core structure can be considered to be synthetic precursor for most of the pentacyclic and tetracyclic indole alkaloids of biological interests (Hesse, 2002; Bosch & Bonjoch, 1988; Saxton, 1983), such as akuminicine and uleine. Most of them have the pentacyclic ring system as a common element and include a large group of naturally occurring compounds such as strychnine, a consulvant poison.

The structures of tricyclic, tetracyclic and pentacyclic ring systems with different substituents of azocino[4,3-b]indole core have been determined, previously. These include N-(2-benzyloxyethyl)-4,7-dimethyl-6-(1,3-dithiolan- 2yl)-1,2,3,4,5,6-hexahydro-1,5-methano-2-azocino[4,3-b]indole-2-one, (II) (Hökelek et al., 2004), 12-ethyl-2-methyl-6,6-ethylenedithio-1,2,3,4,5,6 -hexahydro-1,5-methano-2-azocino[4,3-b]indole-3-one, (III) (Uludağ et al., 2006), 4-ethyl-6,6-ethylenedithio-2-(2-methoxymethyl)-7-methoxymethylene-2, 3,4,5,6,7-hexahydro-1,5-methano-1H-azocino[4,3-b]indole-3-one, (IV) (Hökelek et al., 2006) and 2-(2,2-dimethoxyethyl)-3-oxo-1,2,3,4,5,6 -hexahydro-1,5-methano-7H-azocino[4,3-b]indole, (V) (Hökelek et al., 2007). The present study was undertaken to ascertain the crystal structure of the title compound, (I).

The molecule of the title compound, (I), (Fig. 1) consists of a tetracyclic system containing an azocino skeleton with ethyl, dithiolane and methoxy methylene groups as substituents at positions N2, 6 and N7, respectively. The bonds N7—C6a [1.398 (3) Å] and N7—C7a [1.387 (3) Å] agree well with those in compounds (II) [1.392 (8) and 1.370 (8) Å], (IV) [1.393 (4) and 1.386 (5) Å] and (V) [1.377 (3) and 1.376 (3) Å]. In all four structures atom N7 is substituted. The absolute configurations of C1 and C5 are S and S (Fig. 1). The S atoms of the dithiolane ring have electron-releasing properties, but the N atom at position 7 and the O atom attached to C3 have electron-withdrawing properties, leading to some changes in the bond lengths and angles of the carbazole skeleton.

An examination of the deviations from the least-squares planes through individual rings shows that rings A (C7a/C8/C9/C10/C11/C11a) and B (N7/C7a/C11a/C11b/C6a) are planar. They are also coplanar with a dihedral angle of A/B = 2.78 (11)°. Rings C (C1/C11b/C6a/C6/C5/C12), D (C1/N2/C3/C4/C5/C12) and E (C6/S1/S2/C13/C14) are, of course, not planar. Atom C12 deviates from the planes of F(C1/C5/C6/C6a/C11b) and G (C1/N2/C3/C4/C5) by -0.718 (3) Å and 0.747 (3) Å, respectively where the dihedral angle between planes of F and G is F/G = 68.92 (10)°. On the other hand, the dihedral angles between the plane of H (C1/C5/C12) and the planes of F and G are 54.95 (20)° and 56.61 (20)°, respectively. Ring E has a local pseudo-mirror plane running through C13 and the midpoint of the C6—S2 bond. The conformation of ring E is an envelope, with atom C13 at the flap position, 0.729 (3) Å from the mean plane through the other four atoms.

In the crystal structure, intermolecular C—H···O hydrogen bonds (Table 1) link the molecules into chains nearly parallel to c axis (Fig. 2), in which they may be effective in the stabilization of the structure. There are also two C—H···π interactions (Table 1).

Experimental

The title compound, (I), was prepared from sodium hydride (48.0 mg, 2.00 mmol) and 6-(1,3-dithiolan-2-yl)-1,2,3,4,5,6-hexahydro-1,5-methano-azocino[4,3–6] indole-3-one (500.0 mg, 1.38 mmol) in THF (40 ml) and bromoethane (5 ml). The mixture was heated at reflux for 4 h under nitrogen atmosphere. Later the mixture was cooled in an ice bath and methanol (5 ml) and water (25 ml) were added. After extraction with ethyl acetate (30 ml), the organic layer was dried with Na₂SO₄ and the solvent was evaporated. The residue was crystallized from aceton (yield; 450.0 mg, 83%), m.p. 469 K.