To a stirred solution of 5-(4-chloro-phenyl)-6-(2,2,2-trifluoro-ethoxy)-pyridazine-3-carboxylic acid (example M, 100 mg, 0.300 mmol) in dimethylformamide (4 mL, dried), was added 4-methylmorpholine (CAS No. 109-02-4, 0.09 mL 0.901 mmol), HBTU (CAS No. 94790-37-1, 171 mg, 0.450 mmol), 5-cyclopropyl-[1,2,4]oxadiazol-3-methanamine hydrochloride (Chembridge, MFCD09864586, 52 mg, 0.300 mmol) at rt and this mixture was stirred for 12 h at rt. Volatile were removed under reduced pressure and the residue was extracted with ethyl acetate. The combined organic layer was washed with aq. NaHCO3 soln, brine and concentrated to afford the crude residue which was purified by column chromatography (100-200 silica gel, elution with ethyl acetate/hexane). The title compound (91 mg, 66.0% yield) was obtained as a white solid; LC-MS (UV peak area/ESI) 96.8%, 454.6 (M+H)+.
