2,2-Dichloro-1-[(2R,5S)-5-ethyl-2-methyl-2-propyl-1,3-oxazolidin-3-yl]ethanone

In the title compound, C11H19Cl2NO2, the oxazolidine ring is in an envelope conformation with the O atom forming the flap. In the crystal structure, molecules are linked by weak intermolecular C—H⋯O hydrogen bonds, forming chains.

In the title compound, C 11 H 19 Cl 2 NO 2 , the oxazolidine ring is in an envelope conformation with the O atom forming the flap. In the crystal structure, molecules are linked by weak intermolecular C-HÁ Á ÁO hydrogen bonds, forming chains.
The molecular structure of the title compound is shown in Fig. 1. In the crystal structure, molecules are linked by weak intermolecular C-H···O hydrogen bonds to form one-dimensional chains (Fig. 2).

Experimental
The title compound was prepared according to the literature procedure (Fu et al., 2009). The single crystal suitable for X-ray structural analysis was obtained by slow evaporation in petroleum ether and ethyl acetate at room temperature. The title enantiomer spontaneously resolved from a racemic mixture during the crystallization.

Refinement
All H atoms were initially located in a different Fourier map. The C-H atoms were then constrained to an ideal geometry, with C-H = 0.96-0.98 Å and U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms. Fig. 1. The molecular structure of the title compound, with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

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.
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.