6-Methoxy-1-(4-methoxyphenyl)-1,2,3,4-tetrahydro-9H-β-carbolin-2-ium acetate

In the title compound, C19H21N2O2 +·C2H3O2 −, the 1H-indole ring system is essentially planar [maximum deviation = 0.0257 (14) Å] and forms a dihedral angle of 87.92 (7) Å with the benzene ring attached to the tetrahydropyridinium fragment. The tetrahydropyridinium ring adopts a half-chair conformation. In the crystal, cations and anions are linked by interionic N—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds into chains along the a axis.


Kun Fun Comment
The metal complexes of 6-methoxy-1-methyl-4,9-dihydro-3H-β-carboline and other carboline alkaloids were previously reported to have biological activity (Al-Allaf et al. 1990). It is now well established that these class of beta carboline alkaloids may occur under mild conditions in foods from a Pictet-Spengler condensation of indoleamines such as Ltryptophan and short aliphatic aldehydes (Herraiz et al. 2003). Our present work intend to synthesize this compound and prepare it in salt form to investigate its safety and antiproliferative efficacy in cancer cell line.
All bond lengths and angles in the title compound (  (Table 1) into one-dimensional chains along the a axis (Fig. 2).

Refinement
N-bound H atoms were located in a difference Fourier map and refined using a riding model with U iso (H) = 1.2 U eq (N).
The remaining H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-1.00 Å and U iso (H) = 1.2 U eq (C) or 1.5 U eq (C) for methyl H atoms. A rotating group model was applied to the methyl groups.

Figure 1
The molecular structure, showing 50% probability displacement ellipsoids. An interionic hydrogen bond is shown as a dashed line.  The crystal packing of the title compound. Dashed lines indicate hydrogen bonds. H atoms not involved in the hydrogen interactions have been omitted for clarity.  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 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.