DIPEA (0.138 mL, 0.80 mmol) was added drop wise to benzoic acid (39 mg, 0.32 mmol) in DMF (5 mL). EDCI (127 mg, 0.67 mmol) and HOBT (43 mg, 0.32 mmol) were added consecutively. After 10 mins, N-(2-Oxo-2-piperazin-1-yl-ethyl)-4-phenoxy-benzamide hydrochloride (100 mg, 0.27 mmol) was added and the resulting mixture was stirred at room temperature overnight. Water was then added, and the product was extracted with EtOAc. The organic layer was washed with brine, dried over Na2SO4 and concentrated under reduced pressure to afford the crude product. Purification using column chromatography (silica gel of mesh size of 60-120 using 70:30 EtOAc:hexane as eluent) afforded N-[2-(4-benzoyl-piperazin-1-yl)-2-oxo-ethyl]-4-phenoxy-benzamide in 57% yield. LC-MS purity: 99%, 1H NMR (DMSO-D6): δ 8.6 (t, 1H), 7.9 (d, 2H), 7.5 (m, 7H), 7.2 (t, 1H), 7.1 (m, 4H), 4.2 (d, 2H), 3.6 (m, 8H).
