2,4-Bis(4-ethoxyphenyl)-3-azabicyclo[3.3.1]nonan-9-one

The title compound, C24H29NO3, exists in a twin-chair conformation with an equatorial orientation of the 4-ethoxyphenyl groups. The benzene rings are inclined to each other at an angle of 28.0 (1)°. In the crystal, weak C—H⋯O interactions link molecules related by translation into chains along the b axis. The crystal packing exhibits π–π interactions between the benzene rings of neighbouring molecules [centroid–centroid distance = 3.692 (3) Å].

The title compound, C 24 H 29 NO 3 , exists in a twin-chair conformation with an equatorial orientation of the 4-ethoxyphenyl groups. The benzene rings are inclined to each other at an angle of 28.0 (1) . In the crystal, weak C-HÁ Á ÁO interactions link molecules related by translation into chains along the b axis. The crystal packing exhibitsinteractions between the benzene rings of neighbouring molecules [centroid-centroid distance = 3.692 (3) Å ].

Comment
Alkaloids with 3-azabicyclononane nucleus display broad-spectrum of biological activities ranging from antibacterial to anticancer (Barker et al., 2005;Parthiban et al., 2009Parthiban et al., , 2010aParthiban et al., , 2010bParthiban et al., , 2011a. Hence, the synthesis of new molecules that contain 3-azabicyclononane pharmacophore as well as their isolaton from the natural products are important in the field of medicinal chemistry. Accordingly, we synthesized the title compound by a non-laborious method to explore its stereochemistry in the solid-state. Examination of the asymmery parameters and torsion angles of the title compound reveal that the values are similar to those observed in the analogs viz., 2,4-bis-(4-ethoxyphenyl)-7-methyl-3-azabicyclo[3.3.1]nonan-9-one (Park et al., 2012) and 2,4-bis-(2-ethoxyphenyl)-7-methyl -3-azabicyclo The crystal packing is stabilized by the weak intermolecular C-H···O hydrogen bonds (Table 1) and π-π interactions.

Experimental
The 2,4-bis-(4-ethoxyphenyl)-3-azabicyclo[3.3.1]nonan-9-one was synthesized by a modified and an optimized Mannich condensation in one-pot, using 4-ethoxybenzaldehyde (0.1 mol, 15.018 g/13.91 ml), cyclohexanone (0.05 mol, 4.90 g/5.18 ml) and ammonium acetate (0.075 mol, 5.78 g) in a 50 ml of absolute ethanol (Park et al., 2011). The mixture was gently warmed on a hot plate at 303-308 K (30-35° C) with moderate stirring till the complete consumption of the starting materials, which was monitored by TLC. At the end, the crude azabicyclic ketone was separated by filtration and gently washed with 1:5 cold ethanol-ether mixture. X-ray diffraction quality crystals of the title compound were obtained by slow evaporation from ethanol.

Figure 1
Anistropic displacement representation of the molecule with atoms represented with 30% probability ellipsoids. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O3