In a 40 ml scintillation vial equipped with a magnetic stir bar and fitted with a nitrogen inlet, the 2-chloro-5-nitro-4-(4-o-tolyl-piperazin-1-yl)-benzoic acid 1d (141.40 mg, 0.38 mmol) was taken up in clean, dry N,N-dimethylformamide (3.00 ml, 38.74 mmol) and the mixture was stirred together at room temperature under nitrogen atmosphere until all solids were taken up into solution. To this was added the HATU (171.70 mg, 0.45 mmol) followed by the N,N-diisopropylethylamine (0.20 ml, 1.15 mmol) and the mixture was once again stirred until all solids were in solution. Finally, the 3-(3-amino-propyl)-oxazolidin-2-one 15a (71.22 mg, 0.49 mmol) was added in one portion and the reaction was allowed to stir at room temperature overnight. The reaction was diluted with 10 ml of water and 10 ml of ethyl acetate. The layers were then separated and the product was extracted from the solution using ethyl acetate (3×15 ml). The organic phases were combined, washed with brine (1×25 ml) and saturated aqueous lithium chloride solution (2×25 ml). The solution was dried over Na2SO4; the solution was decanted and the solvent was removed under reduced pressure. The product was then purified using silica gel column chromatography, eluting a gradient of 100% dichloromethane to 10% MeOH in dichloromethane. The product, 2-chloro-5-nitro-N-[3-(2-oxo-oxazolidin-3-yl)-propyl]-4-(4-o-tolyl-piperazin-1-yl)-benzamide 15b (170.60 mg, 0.34 mmol), was isolated as an off-white solid and was carried on without further purification. LCMS=501 (M+H).
