Pyridine → 5-(S)-Acetamidomethyl-3-[4'-methylsulfinyl-3'-fluorophenyl]oxazolidine-2-one

Acetic anhydride (0.173 ml, 1.83 mmol) and pyridine (0.296 ml, 3.67 mmol) were added to a solution of 5-(S)-aminomethyl-3-[4′-methylsulfinyl-3′-fluorophenyl]oxazolidine-2-one (0.100 g, 0.367 mmol) in DCM (3 ml). The reaction mixture was stirred for 4 h at r.t. and then evaporated to dryness under vacuum. The residue was purified by PTLC (10% methanol in DCM) to give product as a white solid (0.115 g, 99%). M.p. 143-5° C. MS (m/z): [M+H]+=315.