3,3-Ethyl­enedithio-3,3a,4,5,10,10b-hexa­hydro-2H-furo[2,3-a]carbazole

Nesimi Uludağ; Aslı Öztürk; Tuncer Hökelek; Ümit Işık Erdoğan

doi:10.1107/S1600536809006035

. 2009 Feb 25;65(Pt 3):o595–o596. doi: 10.1107/S1600536809006035

3,3-Ethylenedithio-3,3a,4,5,10,10b-hexahydro-2H-furo[2,3-a]carbazole

Nesimi Uludağ ^a, Aslı Öztürk ^b, Tuncer Hökelek ^b, Ümit Işık Erdoğan ^c,^*

PMCID: PMC2968651 PMID: 21582250

Abstract

The title compound, C₁₆H₁₇NOS₂, consists of a carbazole skeleton with tetrahydrofuran and dithiolane rings. In the indole ring system, the benzene and pyrrole rings are nearly coplanar, forming a dihedral angle of 1.57 (15)°. The cyclohexenone and tetrahydrofuran rings have envelope conformations, while the dithiolane ring adopts a twist conformation. In the crystal structure, pairs of weak intermolecular N—H⋯S hydrogen bonds link the molecules into centrosymmetric dimers with R ₂ ²(16) ring motifs. Weak C—H⋯π interactions may further stabilize the structure.

Related literature

For general background, see: Phillipson & Zenk (1980 ▶); Saxton (1983 ▶); Abraham (1975 ▶). For related structures, see: Hökelek et al. (1994 ▶, 1998 ▶, 1999 ▶, 2004 ▶, 2006 ▶); Patır et al. (1997 ▶); Hökelek & Patır (1999 ▶,2002 ▶); Çaylak et al. (2007 ▶). For bond-length data, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶)

Experimental

Crystal data

C₁₆H₁₇NOS₂
M _r = 303.43
Orthorhombic,
a = 21.7617 (5) Å
b = 8.4992 (2) Å
c = 15.2115 (3) Å
V = 2813.47 (11) Å³
Z = 8
Mo Kα radiation
μ = 0.37 mm⁻¹
T = 294 K
0.35 × 0.20 × 0.15 mm

Data collection

Enraf–Nonius TurboCAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.913, T _max = 0.944
8196 measured reflections
2289 independent reflections
1105 reflections with I > 2σ(I)
R _int = 0.149
3 standard reflections frequency: 120 min intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.108
S = 0.98
2289 reflections
185 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); 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 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809006035/xu2478sup1.cif

e-65-0o595-sup1.cif^{(19.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809006035/xu2478Isup2.hkl

e-65-0o595-Isup2.hkl^{(67.7KB, 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
N10—H10⋯S2ⁱ	0.81 (4)	2.71 (4)	3.487 (4)	161 (4)
C3A—H3A⋯Cg2ⁱⁱ	0.98	2.85	3.725 (4)	149
C4—H4B⋯Cg1ⁱⁱⁱ	0.97	2.79	3.556 (5)	136
C5—H5A⋯Cg1ⁱⁱ	0.97	2.96	3.714 (5)	135

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) . Cg1 and Cg2 are centroids of the C5b/C6–C9/C9a and C5a/C5b/C9a/N10/C10a rings, respectively.

Acknowledgments

The authors acknowledge the purchase of the CAD-4 diffractometer under grant DPT/TBAG1 of the Scientific and Technical Research Council of Turkey.

supplementary crystallographic information

Comment

Tetrahydrocarbazole systems are present in the framework of a number of indole-type alkaloids of biological interest (Phillipson & Zenk, 1980; Saxton, 1983; Abraham, 1975). The structures of tricyclic, tetracyclic and pentacyclic ring systems with dithiolane and other substituents of the tetrahydrocarbazole core, have been the subject of much interest in our laboratory. These include 1,2,3,4-tetrahydrocarbazole-1-spiro-2'-[1,3]dithiolane, (II) (Hökelek et al., 1994), N-(2-methoxyethyl)-N-{2,3,4,9-tetrahydrospiro[1H-carbazole-1, 2-(1,3)dithiolane]-4-yl}benzene-sulfonamide, (III) (Patır et al., 1997), spiro[carbazole-1(2H),2'-[1,3]-dithiolan]-4(3H)-one, (IV) (Hökelek et al., 1998), 9-acetonyl-3-ethylidene-1,2,3,4-tetrahydrospiro[carbazole-1,2'-[1,3] dithiolan]-4-one, (V) (Hökelek et al., 1999), N-(2,2-dimethoxyethyl)-N -{9-methoxymethyl-1,2,3,4-tetrahydrospiro[carbazole-1,2'-[1,3]dithiolan] -4-yl}benzamide, (VI) (Hökelek & Patır, 1999), 3a,4,10,10b-tetrahydro-2H -furo[2,3-a]carbazol-5(3H)-one, (VII) (Çaylak et al., 2007); also the pentacyclic compounds 6-ethyl-4-(2-methoxyethyl)-2,6-methano-5-oxo-hexahydro- pyrrolo(2,3 - d)carbazole-1-spiro-2'-(1,3)dithiolane, (VIII) (Hökelek & Patır, 2002), N-(2-benzyloxyethyl)-4,7-dimethyl-6-(1,3-dithiolan-2-yl)-1,2, 3,4,5,6-hexahydro-1,5-methano-2-azocino[4,3-b]indol-2-one, (IX) (Hökelek et al., 2004) and 4-ethyl-6,6-ethylenedithio-2-(2-methoxyethyl)-7-methoxy- methylene-2,3,4,5,6,7-hexahydro-1,5-methano-1H-azocino[4,3-b]indol-3-one, (X) (Hökelek et al., 2006). The title compound, (I), may be considered as a synthetic precursor of tetracyclic indole alkaloids of biological interests. The present study was undertaken to ascertain its crystal structure.

In the molecule of the title compound (Fig. 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges. It consists of a carbazole skeleton with tetrahydrofuran and dithiolane rings. The bonds N10—C9a [1.378 (5) Å] and N10—C10a [1.371 (5) Å] generally agree with those in compounds (II)-(X). In all structures atom N10 is substituted.

An examination of the deviations from the least-squares planes through individual rings shows that rings A (C5b/C6—C9/C9a) and B (C5a/C5b/C9a/N10/C10a) are planar. They are also nearly coplanar with a dihedral angle of A/B = 1.57 (15)°. Rings C (C3a/C4/C5/C5a/C10a/C10b), D (O1/C2/C3/C3a/C10b) and E (S1/S2/C3/C11/C12) are not planar. Rings C and D have envelope conformations with atoms C4 and C3 displaced by -0.677 (4) Å (for ring C) and 0.568 (4) Å (for ring D) from the planes of the other ring atoms, respectively. Ring E adopts twisted conformation. Rings C and D have pseudo mirror planes running through atoms C10a and C4 (for ring C) and running through atom C3 and midpoint of O1—C10b bond (for ring D), as can be deduced from the torsion angles (Table 1).

In the crystal structure, intermolecular N—H···S hydrogen bonds (Table 2) link the molecules into centrosymmetric dimers (Fig. 2) by forming the R₂²(16) ring motifs (Bernstein et al., 1995), in which they may be effective in the stabilization of the structure. The weak C—H···π interactions (Table 1) may further stabilize the structure.

Experimental

For the preparation of the title compound, (I), sodium borohydride (5.00 g, 132.00 mmol) was added to a solution of ethyl 2-(1-oxo-2,3,4,9-tetrahydro-1H -carbazol-2yl)-1,3-dithiolane-2-carboxylate (5.00 g, 13.83 mmol) in THF (50 ml), and stirred at room temperature for 3 h. Then, the reaction mixture was poured into HCl (15%, 100 ml). The crude product was filtered and recrystallized from acetone (yield; 3.2 g, 77%, m.p. 468 K).