(S)-2-[(S)-2,2,2-Trifluoro-1-hydroxyethyl]-1-tetralone

The title tetralone derivative crystallizes in the Sohncke space group P21 and features one molecule in the asymmetric unit. In the crystal, molecules are hydrogen-bonded into infinite zigzag chains running parallel to [010].

The crystal structure of the title compound, C 12 H 11 F 3 O 2 , was elucidated by low-temperature single-crystal X-ray diffraction. The enantiopure compound crystallizes in the Sohncke space group P2 1 and features one molecule in the asymmetric unit. The structure displays intermolecular O-HÁ Á ÁO hydrogen bonding, which links the molecules into infinite chains propagating parallel to [010]. The absolute configuration was established from anomalous dispersion.

Structure description
Dynamic kinetic resolution (DKR) based on Ru II -catalyzed Noyori-Ikariya asymmetric transfer hydrogenation (ATH) has proven to be a highly efficient strategy for the stereoconvergent synthesis of secondary alcohols (Cotman, 2021). The commercial availability of a wide range of Ru II catalysts, comparatively mild reaction conditions, and the ability to use racemic mixtures of ketones as starting materials make this approach particularly attractive for the synthesis of -substituted benzyl alcohols, which have been shown to be valuable building blocks for pharmaceuticals and can crystallize as homochiral single-component mechanically responsive crystals that exhibit elastic or plastic flexibility (Cotman et al., 2019(Cotman et al., , 2022. When ATH of non-symmetric CF 3 -substituted 1,3diketones was attempted, it was found that two consecutive DKR-ATH reactions can occur and that diastereo-and enantiopure 1,3-diols can be obtained in a one-pot process (Cotman et al., 2016). The use of milder reaction conditions enabled the preparation of mono-reduced alcohols, which include the title compound.
In the crystal structure of the title compound, intermolecular O-HÁ Á ÁO hydrogen bonds with an OÁ Á ÁO distance of 2.7548 (16) Å (Table 1), involving hydroxyl and carbonyl groups of the adjacent molecules related by the 2 1 screw axis, link the molecules into infinite zigzag chains propagating parallel to [010] (Figs. 2, 3). The graph-set motif of the chains is C(6) (Etter et al., 1990).

Synthesis and crystallization
The title compound was prepared from 2-trifluoroacetyl-1tetralone (242 mg, 1.0 mmol) added to a HCO 2 H/Et 3 N 5:2    Molecular structure of the title compound and the atom-labeling scheme. Displacement ellipsoids are shown at the 50% probability level and hydrogen atoms are depicted as spheres of arbitrary radius.
(0.5 ml) solution containing the active (S,S)-diphenylethylenediamine-based Ru II catalyst with an S:C ratio of 2000:1 (Cotman et al., 2016). Upon addition of the co-solvent chlorobenzene (1 ml), the mixture was warmed to 40 C and stirred for 23 h, while being continuously flushed with N 2 . The resulting mixture was partitioned between EtOAc (10 ml) and H 2 O (5 ml), with the organic layer later washed with H 2 O (5 ml) and brine (5 ml), filtered through a bed of silica gel/ Na 2 SO 4 , and concentrated. The procedure resulted in the formation of a crude white product (239 mg, 98% yield), containing the title compound (d.r. = 89:11, 72% ee) and 2.5% of the corresponding diol. After purification by flash chromatography (hexane/EtOAc gradient 9:1 to 7:1), the diastereomerically pure monoalcohol was isolated (157 mg, 64% yield). The enantiomeric excess was upgraded to >99% by crystallization from cyclohexane (109 mg, 45% yield). Crystals suitable for single-crystal X-ray diffraction analysis were grown from a chloroform solution. A suitable crystal was selected under a polarizing microscope and mounted on a MiTeGen Dual Thickness MicroLoop LD using Baysilone-Paste (Bayer-Silicone, mittelviskos).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. Standard uncertainties involving l.s. planes were estimated using ShelXL matrix (within Olex2). 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.