To a stirred solution of ethyl [trans-4-({[2-({(4S,5R)-5-[3,5-bis(trifluoromethyl)phenyl]-4-methyl-2-oxo-1,3-oxazolidin-3-yl}methyl)-4-(trifluoromethoxy)phenyl]amino}methyl)cyclohexyl]acetate (Step A; 50 mg; 0.73 mmol) in CH2Cl2 (3 mL) was added methyl chloroformate (50 μL) followed by diisopropylethylamine (102 μL; 0.585 mmol). The reaction stirred at 40° C. for 24 h. The reaction was diluted with EtOAc (25 mL) and washed successively with sat. NaHCO3, brine, 1N HCl and brine (15 mL each), dried (MgSO4), filtered and concentrated in vacuo. The residue was purified by flash silica gel chromatography (0-25% EtOAc/hexanes gradient) and chiral HPLC (4% IPA/heptane; AD column) to afford ethyl (trans-4-{[[2-({(4S,5R)-5-[3,5-bis(trifluoromethyl)phenyl]-4-methyl-2-oxo-1,3-oxazolidin-3-yl}methyl)-4-(trifluoromethoxy)phenyl](methoxycarbonyl)amino]methyl}cyclohexyl)acetate as a clear glass. LCMS=743.2 (M+1)+. 1H NMR (CDCl3, 500 MHz): δ 7.90-7.85 (m, 1 H), 7.78 (s, 1 H), 7.75 (s, 1 H), 7.27-7.17 (m, 3 H), 5.71 (d, J=8.0 Hz, 1 H), 5.00-4.54 (m, 1 H), 4.12 (q, J=7.1 Hz, 2 H), 4.10-4.02 (m, 1 H), 3.98-3.82 (m, 2 H), 3.80-3.58 (m, 3 H), 3.14-3.00 (m, 1 H), 2.17 (d, J=6.9 Hz, 2 H), 1.87-1.66 (m, 4 H), 1.52-1.41 (m, 2 H), 1.25 (t, J=7.1 Hz, 3 H), 1.13-0.94 (m, 4 H), 0.69 (d, J=6.4 Hz, 3 H).
