(4-Benzyl-2-oxo-1,3-oxazolidin-5-yl)methyl methanesulfonate

The title compound, C12H15NO5S, features an approximately planar five-membered oxazolidin ring (r.m.s. deviation = 0.045 Å) with the peripheral benzyl and methyl methanesulfonate residues lying to either side of the plane. In the crystal, N—H⋯O hydrogen bonds, involving one of the sulfur-bound oxo groups as acceptor, lead to the formation of supramolecular chains along the b axis. These chains are reinforced by C—H⋯O contacts with the carbonyl O atom accepting three such interactions. The structure was refined as a racemic twin, with the major component being present 89% of the time.

The title compound, C 12 H 15 NO 5 S, features an approximately planar five-membered oxazolidin ring (r.m.s. deviation = 0.045 Å ) with the peripheral benzyl and methyl methanesulfonate residues lying to either side of the plane. In the crystal, N-HÁ Á ÁO hydrogen bonds, involving one of the sulfur-bound oxo groups as acceptor, lead to the formation of supramolecular chains along the b axis. These chains are reinforced by C-HÁ Á ÁO contacts with the carbonyl O atom accepting three such interactions. The structure was refined as a racemic twin, with the major component being present 89% of the time.
The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil).
The oxazolidin ring in (I), Fig. 1, is essentially planar with the maximum deviations of 0.036 (5) Å for atom C5 and -0.040 (4) Å for atom N1. The O5 atom lies 0.089 (3) Å out of the plane in the direction of the C2 atom, and the C6 atom is below the plane. The C2-C3-C5-C6 torsion angle of 124.6 (4) ° shows a significant twist consistent with the methanesulfonate residue being splayed out from the rest of the molecule. The methanesulfonate-methyl group is oriented towards the ring-O4 atom. Supramolecular chains are formed in the crystal structure of (I) along the b direction. These are sustained by N-H···O hydrogen bonds where the oxygen acceptor is an sulfur-bound oxo group, Fig. 2 and Table 1. Three close C-H···O-carbonyl contacts, Table 1, provide additional stability to the chain. Chains are linked into supramolecular arrays in the bc plane via weaker C-H···O contacts and these stack along the a axis, Fig. 3 and Table 1.
The methyl H atoms were rotated to fit the electron density. The N-H atom was located in a difference map and refined supplementary materials sup-2 with the distance restraint N-H = 0.88±0.01 and with U iso (H) = 1.2U eq (N). The structure was refined as a racemic twin precluding the determination of the absolute structure. Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.  (4-Benzyl-2-oxo-1,3-oxazolidin-5-yl)methyl methanesulfonate

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The 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 > 2σ(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.