A part of the crude product of 5-chloro-3-(4,4-difluorocyclohexylmethyl)-2-trifluoromethylimidazo[1,2-a]pyridine-7-carboxylic acid obtained in step 3 (28 mg) was dissolved in DMF (2.0 mL), and the solution was stirred overnight at room temperature after adding EDC.HCl (27 mg, 0.141 mmol), HOBt.H2O (22 mg, 0.141 mmol), and aniline (13 mg, 0.141 mmol). The reaction mixture was extracted with ethyl acetate after adding a sodium hydrogen carbonate aqueous solution. The organic layer was washed with water and saturated brine, and dried over anhydrous sodium sulfate. The solvent was then evaporated under reduced pressure. The residue was purified by preparative thin-layer chromatography (chloroform/methanol=9/1) to give 5-chloro-3-(4,4-difluorocyclohexylmethyl)-N-phenyl-2-trifluoromethylimidazo[1,2-a]pyridine-7-carboxamide (18.0 mg, two-step yield 62%).
