6,6-[Ethylenebis(sulfanediyl)]-2-(2-methoxyethyl)-1,2,3,4,5,6-hexahydro-1,5-methano-1H-azocino[4,3-b]indol-3-one

The title compound, C19H22N2O2S2, consists of a tetracyclic ring system containing an azocine skeleton with methoxyethyl and dithiolane groups as substituents. The benzene and five-membered N-heterocyclic rings are nearly coplanar, making a dihedral angle of 0.81 (12)°. The dithiolane ring adopts an envelope conformation. Intermolecular N—H⋯O hydrogen-bonding and weak C—H⋯π interactions are present in the crystal structure.

The title compound, C 19 H 22 N 2 O 2 S 2 , consists of a tetracyclic ring system containing an azocine skeleton with methoxyethyl and dithiolane groups as substituents. The benzene and fivemembered N-heterocyclic rings are nearly coplanar, making a dihedral angle of 0.81 (12) . The dithiolane ring adopts an envelope conformation. Intermolecular N-HÁ Á ÁO hydrogenbonding and weak C-HÁ Á Á interactions are present in the crystal structure.

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 occuring compounds such as strychnine, a consulvant poison, and uleine alkaloids.
The molecule of the title compound, (I), (Fig. 1) consists of a tetracyclic ring system containing an azocino skeleton with methoxyethyl and dithiolane groups as substituents at positions N2 and 6, respectively. The bonds N7-C6a 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 = 0.81 (12)°.
In the crystal structure, intermolecular N-H···O hydrogen bonds (Table 1) link the molecules into chains nearly parallel to b-axis (Fig. 2), in which they may be effective in the stabilization of the structure. A weak C-H···π interaction also occurs (Table 1).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.