Crystal structure of (4-hydroxypiperidin-1-yl)[4-(trifluoromethyl)phenyl]methanone

The title compound, C13H14NO2F3, crystallises with two molecules, A and B, in the asymmetric unit, with similar conformations. The dihedral angles between the piperidine and phenyl rings are 83.76 (2) and 75.23 (2)° in molecules A and B, respectively. The bond-angle sums around the N atoms [359.1 and 359.7° for molecules A and B, respectively] indicate sp 2 hybridization for these atoms. In the crystal, O—H⋯O hydrogen bonds link the molecules into separate [100] chains of A and B molecules. The chains are cross-linked by C—H⋯O interactions, generating alternating (001) sheets of A and B molecules.

The motivation for the biological trial arises as piperidine derivatives are an important class of heterocyclic compounds with potent pharmacological/ biological activities (Ramalingan et al., 2004;Ramachandran et al., 2011). Heterocycles with piperidine sub-structures are being used as synthons in the construction of alkaloid natural products (Lee et al., 2001). Piperidine derivatives exhibit a broad-spectrum of biological activities such as anti-bacterial and anti-cancer (Parthiban et al., 2005).
In the title compound,the C-N distances of piperidine ring in molecule  .

S2. Experimental
The title compound was synthesized following a published procedure . In a 250 ml round-bottomed flask, 100 ml of ethylmethylketone was added to 4-hydroxypiperidiene (0.03 mol) and stirred at room temperature. After a span of about 5 min, triethylamine (0.03 mol) was added and the mixture was stirred for a time frame of 10 min. 4-Trifloromethylbenzoyl chloride (0.03 mol) was added and the reaction mixture was stirred at room temperature for about 2 h. A white precipitate of triethylammonium chloride was produced, which was filtered and the filtrate was evaporated to get the crude product. Two recrystallizations from ethylmethylketone solution gave colourless blocks of the title compound (yield: 87%).

S3. Refinement
Hydrogen atoms other then hydroxy H atoms were positioned geometrically and treated as riding on their parent atoms and hydroxy H-atoms were located from difference Fourier maps and refined with,C-H distance of 0.93-0.98 Å, with

Figure 1
The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level.

Figure 2
The packing of the molecules in the crystal structure. The dashed lines indicate the hydrogen bonds.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.27 e Å −3 Δρ min = −0.26 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.   Symmetry codes: (i) x+1/2, −y+1/2, z; (ii) x−1/2, −y+1/2, z; (iii) x, y−1, z; (iv) −x+2, −y, z+1/2.