(S)—N-{3-[3-Fluoro-4-(4-{2-[4-(2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazin-6-yloxymethyl)-phenoxy]-acetyl}-piperazin-1-yl)-phenyl]-2-oxo-oxazolidin-5-ylmethyl}-acetamide. A solution of [4-(2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazin-6(S)-yloxylmethyl)-phenoxy]-acetic acid tert-butyl ester (100 mg, 0.25 mmol) in TFA/CH2Cl2 (2 mL) was stirred at room temperature for 2 h. The resultant mixture was concentrated in vacuo, and diluted with DCM, to the solution was added N-[3-(3-fluoro-4-piperazin-1-yl-phenyl)-2-oxo-oxazolidin-5-ylmethyl]-acetamide (50 mg, 0.15 mmol) (prepared by following the procedure disclosed by U.S. Pat. No. 5,547,950 or Brickner 1996), HOBt (21.6 mg, 0.16 mmol), EDCI (30.7 mg, 0.16 mmol) and DIPEA (0.20 ml). The mixture was stirred at room temperature for 24 hours diluted with DCM, washed with sat. NaHCO3, 1 N HCl and sat. NaHCO3, dried over sodium sulfate, and concentrated in vacuo. The crude product was purified by preparative TLC plates (5% MeOH in dichloromethane) to give the title product as a solid (6.0 mg, 4%). ESI MS m/z 668.4 (M+H+).
