5-[4-(Trifluoromethyl)phenyl]isoxazole-4-carboxylic acid (30 mg, 0.12 mmol) was dissolved in acetonitrile (1.5 mL) followed by the addition of o-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate (TBTU) (52 mg, 0.16 mmol), pyridine (60 μL, 0.72 mmol) and 3-(4-fluorophenyl)pyrrolidine oxalate (36 mg, 0.14 mmol), and stirred at 60° C. for 2 h. The residue was purified on reversed phase HPLC to yield the title compound (8 mg). HRMS (ESI, pos. ion) m/z calcd for C21H16F4N2O2: 404.1148, found 404.1152.
