HOBt (40 mg, 0.3 mmol) and DMAP (46 mg, 0.37 mmol) were added to a stirred solution of 3-oxo-3-[4-(3,4,5-trifluoro-benzoyl)-piperazin-1-yl]-propionic acid (83 mg, 0.25 mmol) in DMF (2 mL). The reaction mixture was cooled to 10° C. and EDCI.HCl (58 mg, 0.3 mmol) followed by 6-phenyl-pyridin-3-ylamine (51 mg, 0.3 mmol) were added. The reaction mixture was stirred at room temperature overnight, diluted with water and the product was extracted with ethyl acetate. The organic layer was washed with brine solution, dried over Na2SO4 and concentrated to afford 44 mg (36%) of 3-oxo-N-(6-phenyl-pyridin-3-yl)-3-[4-(3,4,5-trifluoro-benzoyl)-piperazin-1-yl]-propionamide. LCMS: 483.16 (M+1)+, 97.0%, 1H NMR: (DMSO-d6): δ 10.5 (s, 1H), 8.8 (d, 1H), 8.2-8.1 (m, 1H), 8.1 (d, 2H), 8.0 (d, 1H), 7.6-7.4 (m, 5H), 3.4-3.2 (m. 10H).
