In a 40 ml scintillation vial equipped with a magnetic stir bar and fitted with a nitrogen inlet, the 2-chloro-5-[(furan-2-carbonyl)-amino]-4-(4-o-tolyl-piperazin-1-yl)-benzoic acid 14b (135.70 mg, 0.31 mmol) was taken up in clean, dry N,N-dimethylformamide (4.00 ml, 51.66 mmol) and the mixture was stirred at room temperature under nitrogen until all solids were in solution. To this was added first the HATU (140.80 mg, 0.37 mmol) followed by the N,N-diisopropylethylamine (0.16 ml, 0.92 mmol) and the mixture was once again stirred until all solids were in solution. The 3-dimethylaminomethyl-benzylamine (76.00 mg, 0.46 mmol) was added and the reaction stirred at room temperature overnight. The reaction was diluted with 10 ml of water and 10 ml of ethyl acetate. The layers were separated and the product was extracted from the aqueous 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 product solution was dried over Na2SO4; the solution was then decanted and the solvent was removed under reduced pressure. The product was isolated using silica gel column chromatography, eluting a gradient of 100% dichloromethane to 10% MeOH in dichloromethane. A secondary purification was required, using reverse-phase prep HPLC, eluting a gradient of 30% MeOH in water to 100% MeOH over a 5 min period. The product, furan-2-carboxylic acid [4-chloro-5-(3-dimethylaminomethyl-benzylcarbamoyl)-2-(4-o-tolyl-piperazin-1-yl)-phenyl]-amide 14c (37.30 mg, 0.06 mmol), was isolated as an off-white solid.
