Ethyl 4,9-dimethyl-9H-carbazole-3-carboxylate

In the title compound, C17H17NO2, the carbazole skeleton includes an ethoxycarbonyl group at the 3-position. The indole three-ring system is almost planar [maximum deviation = 0.065 (2) Å], and the ethyl ester group is inclined to its mean plane by 15.48 (2)°. In the crystal, there are π–π stacking interactions between parallel benzene rings and between parallel benzene and pyrrole rings of adjacent molecules [centroid–centroid distances = 3.9473 (8) and 3.7758 (8) Å, respectively]. Weak C—H⋯π interactions are also present.

In the title compound, C 17 H 17 NO 2 , the carbazole skeleton includes an ethoxycarbonyl group at the 3-position. The indole three-ring system is almost planar [maximum deviation = 0.065 (2) Å ], and the ethyl ester group is inclined to its mean plane by 15.48 (2) . In the crystal, there arestacking interactions between parallel benzene rings and between parallel benzene and pyrrole rings of adjacent molecules [centroid-centroid distances = 3.9473 (8) and 3.7758 (8) Å , respectively]. Weak C-HÁ Á Á interactions are also present.

Related literature
For the first isolation of carbazole from coal tar, see: Graebe & Glazer (1872). For the isolation of murrayanine, the first report of a naturally occurring carbazole alkaloid, see: Chakraborty et al. (1965). For the intriguing structural features and promising biological activities exhibited by many carbazole alkaloids, see: Chakraborty (1993). For the syntheses of pyridocarbazoles, see: Karmakar et al. (1991). For related structures, see: Hö kelek et al. (1994); Patır et al. (1997). For bond-length data, see: Allen et al. (1987).  Table 1 Hydrogen-bond geometry (Å , ). the first report of a naturally occurring carbazole alkaloid (Chakraborty et al., 1965). Since then there has been a strong interest in this area by chemists and biologists due to the intriguing structural features and promising biological activities exhibited by many carbazole alkaloids (Chakraborty, 1993). Most carbazole alkaloids have been isolated from the taxonomically related higher plants of the genus Murraya, Glycosmis and Clausena from the family Rutaceae. The genus

Experimental
Murraya represents the richest source of carbazole alkaloids from terrestrial plants. The title compound was used as a precursor compound for the syntheses of pyridocarbazoles (Karmakar et al., 1991) and we report herein on its crystal structure.
The molecule of the title compound, Fig. 1, contains a carbazole skeleton with an ethoxycarbonyl group at the 3 position. The bond lengths are close to standard values (Allen et al., 1987) and generally agree with those in previously reported compounds (Hökelek et al., 1994;Patır et al., 1997). In all structures atom N9 is substituted.

Refinement
The C-bound H-atoms were positioned geometrically with C-H = 0.93, 0.97 and 0.96 Å, for aromatic, methylene and methyl H-atoms, respectively, and constrained to ride on their parent atoms, with U iso (H) = k × U eq (C), where k = 1.5 for

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 > 2sigma(F 2 ) is used only for calculating R-factors(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.