Crystal structure of (S)-5-(3-acetyl-5-chloro-2-ethoxy-6-fluorophenyl)-2-oxazolidinone

The structure of (S)-5-(3-acetyl-5-chloro-2-ethoxy-6-fluorophenyl)-2-oxazolidinone has been determined to establish its absolute configuration in efforts to synthesize an anticancer drug candidate, parsaclisib.


Structural commentary
The asymmetric unit consisting of one complete molecule of the title compound is shown in Fig. 1.Consistent with similar structures (vide infra), the oxazolidinone ring is essentially planar and is twisted from the plane of the dihalophenyl ring as seen from twist angles C2-C3-C4-C9 = 70.5 (5) � .One of the two symmetry-unique molecules in (R)-5-mesityloxazolidin-2-one has the closest similar twist of 73.5 (2) � (Qin et al., 2012).The acetate and ethoxy groups in the title compound are almost perpendicular to the phenyl ring with torsion angles C7-C6-C12-O4 = À 92.8 (6) � and C10-O3-C5-C6 = À 96.8 (4) � , respectively.The absolute structure refined to nil indicating the correct handedness has been established.

Refinement
Figure 1 The contents of the asymmetric unit with atom labeling.H-atom labels are omitted for clarity.Displacement ellipsoids are plotted at 50% probability.

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. 1.Fixed Uiso At 1.2 times of: All C(H) groups, All C(H,H) groups, All N(H) groups At 1.5 times of: All C(H,H,H) groups 2.a Ternary CH refined with riding coordinates: C3(H3) 2.b Secondary CH2 refined with riding coordinates: C2(H2A,H2B), C10(H10A,H10B) 2.c Aromatic/amide H refined with riding coordinates: C7(H7) 2.d Idealised Me refined as rotating group: C11(H11A,H11B,H11C), C13(H13A,H13B,H13C)

Figure 2 A
Figure 2 A view perpendicular to the c axis showing hydrogen-bonding interactions (dotted lines) forming a chain parallel to the b axis.Displacement ellipsoids are plotted at 50% probability.

Table 2
Experimental details.