Crystal structure of 2-(2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ylidene)acetonitrile

In the title 3-azabicyclononane derivative, C22H22N2, both the fused piperidine and cyclohexane rings adopt a chair conformation. The phenyl rings attached to the central azabicylononane fragment in an equatorial orientation are inclined to each other at 23.7 (1)°. The amino group is not involved in any hydrogen bonding, so the crystal packing is stabilized only by van der Waals forces.


S1. Chemical context
Nitrile derivatives received considerable interest since they have been used in biological field as well as in optical fields (Silver et al., 1967). Alkenyl nitriles are unique structural units and versatile building blocks in organic synthesis for natural products, pharmaceuticals, agricultural chemicals, and dyes (Fleming & Wang, 2003;Miller & Manson,2001;Fatiadi, 1983). Hence, the synthesis and stereochemistry of 3-azabicyclononan-9-ones are under intensive study (Parthiban et al., 2008a, b, c, d, e). In continuation of our work with 3-azabicyclononane derivatives, we have undertaken the crystal structure determination of the title compound, and the results are presented here.

S3. Supramolecular features
The crystal packing is stabilized by van der Waals forces only, since the amino group is not involved in any hydrogenbonding interactions.

S4. Synthesis and crystallization
To a solution of the 2, 4-diphenyl-3-azabicyclo [3.3.1] nonan-9-one (500 mg, 1.72 mmol) in THF (5 mL), LiOH (212 mg, 3.516mmol) and diethylcyanomethyl phosphonate (364g, 1.4063mmol) was added. The reaction mixture was stirred at for 3 h. After completion of the reaction (monitored by TLC), the reaction mixture was diluted with ethyl acetate (45 mL). The organic layer was washed with water (10 mL X 3) and dried over Na 2 SO 4 . The filtrate was concentrated and the crude product mass was purified by column-chromatography over silica-gel (100-200 mesh) using petroleum ether and diethyl ether (5-10%) as eluent to give a colorless solid. This solid was recrystallized in ethyl acetate to yield a colourless crystals of the title compound.

S5. Refinement
Atom H1N was located from a difference Fourier map and refined with a bond length restraint of 0.90 (2) Å. The remaining H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C-H distances of 0.93-0.98 Å, and U iso (H) = 1.5U eq (C) for methyl H and U iso (H) = 1.2U eq (C) for all other H atoms.

Figure 1
The molecular structure of the title compound with atom labelling. Displacement ellipsoids are drawn at the 40% probability level. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.13 e Å −3 Δρ min = −0.16 e Å −3 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.