(S)-2-Amino-2-(2-chlorophenyl)cyclohexanone

The crystal structure of the title compound, C12H14ClNO, was determined in order to confirm that the chiral center of the molecule has an S configuration. The cyclohexanone ring adopts a chair conformation. The 2-chlorophenyl ring is slightly twisted from the axial C—N bond, with a N—C—C—C torsion angle of −5.7 (2)°. In the crystal, an intermolecular N—H⋯O hydrogen bond links adjacent molecules into an infinite chain, which propagates in the b-axis direction.

The crystal structure of the title compound, C 12 H 14 ClNO, was determined in order to confirm that the chiral center of the molecule has an S configuration. The cyclohexanone ring adopts a chair conformation. The 2-chlorophenyl ring is slightly twisted from the axial C-N bond, with a N-C-C-C torsion angle of À5.7 (2) . In the crystal, an intermolecular N-HÁ Á ÁO hydrogen bond links adjacent molecules into an infinite chain, which propagates in the b-axis direction.
Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and publCIF (Westrip, 2010). it causes minimal respiratory depression in comparison to other anesthetics (Heshmati et al., 2003). S-Ketamine was found 3-4 times more potent as an anesthetic than its R-enantiomer, and twice as potent as Ketalar TM with fewer side effects such as psychedelic, disorientation and anxiety (Kohrs & Durieux, 1998). S-Norketamine, the major metabolite of S-Ketamine in humans and animals, is emerging as a novel drug for treatment of neuropathic pain and for analgesia (Holtman et al., 2006).
To confirm the absolute configuration of (+)-norketamine, herein we report on the X-ray crystallographic characterization of crystalline S-norketamine.
The chirality of the molecule is confirmed (Figure 1). In the structure, the cyclohexanone ring adopts a chair conformation.
The 2-chlorophenyl ring is slightly twisted from the axial C-N bond, with a torsion angle of -5.7 (2)°. In the crystal, an N-H···O hydrogen bond links adjacent molecules into an infinite chain which propagates in the b-axis direction ( Figure 2).

Experimental
With 2-chlorophenyl-1-cyclohexene as pro-chiral starting material, the enantioselective synthesis of S-norketamine was first time accomplished via a 3-step synthesis route. In the first step the chiral quarternary C-1 atom of the ketamine parent structure was generated in utilizing an adapted Sharpless-Asymmetric Dihydroxylation method (Kolb et al., 1994).

Refinement
All non-hydrogen atoms were refined anisotropically. The hydrogen atoms were positioned geometrically and refined as riding atoms. The Flack parameter was determined from 545 Friedel pairs (Flack, 1983 Fig. 1. The asymmetric unit, with displacement ellipsoids drawn at the 30% probability level.  as those based on F, and R-factors based on ALL data will be even larger.
There were problems during data colleciton that were only realised after refinement of the results. The data were quite weak at high angle and although data were collected out to 0.85 Angstrons, the processed data were only 89% complete; however the overall statistics and quality of the results appeared quite good.