N-(Adamantan-1-yl)-2-chloroacetamide

In the title compound, C12H18ClNO, which was synthesized as part of a study into potential antituberculosis agents, the adamantine skeleton displays shorter than normal C—C bond lengths ranging between 1.5293 (18) and 1.5366 (15) Å. The structure also displays intermolecular N—H⋯O hydrogen bonding, which forms an infinite chain in the a-axis direction.

In the title compound, C 12 H 18 ClNO, which was synthesized as part of a study into potential antituberculosis agents, the adamantine skeleton displays shorter than normal C-C bond lengths ranging between 1.5293 (18) and 1.5366 (15) Å . The structure also displays intermolecular N-HÁ Á ÁO hydrogen bonding, which forms an infinite chain in the a-axis direction.

Comment
As part of an ongoing study into the anti-tuberculosis activity of admantane derivatives (Lee et al., 2003, Bogatcheva et al., 2006, Onajole et al., 2010, the title compound, an adamantane derivative, serves as a precursor in the synthesis of potential anti-tuberculosis agents (Onajole et al. 2010). Although, the compound is known (Plakhotnik et al., 1982), its crystal structure has not been reported.
The molecule displays a number of C-C bond lengths that are shorter than the expected bond length of 1.54 Å. These bonds range between 1.5293 (18) Å for C6-C7 to 1.5366 (16) for C1-C2 in the adamantine skeleton (Fig. 1). The structure exhibits intermolecular hydrogen bonding between N1 and O1 of adjacent molecules, which forms an infinite chain in the a-axis direction. The isopropyl (Venkataramanan et al., 2004) amide derivative has a similar bonding arrangement in its structure. Interestingly, the structure report for the bicyclic analogue of the title compund (Fokin et al., 2009) reveals no N-H···O hydrogen bonding in the crystal lattice.

Experimental
Amantadine.HCl (4 g, 26.5 mmol) was dissolved in dichloromethane (40 ml). To this solution was slowly added chloroacetyl chloride (2.987 g, 26.5 mmol) after which the reaction was refluxed gently for 2 h. The reaction mixture was filtered and the resultant solution was concentrated in vacuo. The crude product was purified on silica gel using dichloromethane:ethyl acetate (7:3) as eluent to give the title compound (6.52 g, 89%) as a white crystalline solid. Crystals suitable for X-ray analysis were grown in methanol at room temperature. Melting point: 357-359 K.

Refinement
X-ray single-crystal intensity data were collected on a Nonius Kappa-CCD diffractometer using graphite monochromated MoKa radiation (l = 0.71073 Å). Temperature was controlled by an Oxford Cryostream cooling system (Oxford Cryostat).
The strategy for the data collections was evaluated using the Bruker Nonius "Collect" program (Nonius, 2000). Data were scaled and reduced using DENZO-SMN software (Otwinowski & Minor, 1997). Absorption corrections were performed using SADABS (Sheldrick, 2008). The structure was solved by direct methods and refined employing full-matrix least-squares with the program SHELXL97 (Sheldrick, 2008) refining on F 2 . All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were placed in idealized positions in a riding model with U iso set at 1.2 times those of their parent atoms and refined with simple bond length constraints (e.g. 0.88 Å for N-H and others 0.99 Å).
supplementary materials sup-2 Figures Fig. 1. Molecular structure of the title compound with displacement ellipsoids at the 40% probability level and all hydrogen atoms omitted for clarity. All non-hydrogen atoms are shown as ellipsoids with probability level of 40%.

Special details
Experimental. X-ray single-crystal intensity data were collected on a Nonius Kappa-CCD diffractometer using graphite monochromated MoKa radiation (l = 0.71073?Å). Temperature was controlled by an Oxford Cryostream cooling system (Oxford Cryostat).
The strategy for the data collections was evaluated using the Bruker Nonius "Collect" program (Nonius, 2000). Data were scaled and reduced using DENZO-SMN software (Otwinowski & Minor, 1997). Absorption corrections were performed using SADABS (Sheldrick, 2008). The structure was solved by direct methods and refined employing full-matrix least-squares with the program SHELXL97 (Sheldrick, 2008) refining on F2. All non-hydrogen atoms were refined anisotropically. Half sphere of data collected using COLLECT strategy (Nonius, 2000). Crystal to detector distance = 30 mm; combination of φ and ω scans of 1.0°, 60 s per °, 2 itera- 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 Rfactors(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.