2.0 mL of methylene chloride, 2.7 μL of N,N-dimethylformamide and 0.061 mL of oxalyl chloride were sequentially added to 0.13 g of 3-phenyl-1H-pyrazole-5-carboxylic acid at room temperature and stirred at the same temperature for 1 hour. The reaction mixture was added to a mixed solution of 3.0 mL of methylene chloride and 0.45 mL of triethylamine containing 60 mg of tert-butyl 2-amino-4-phenethylbenzoate at room temperature was stirred at the same temperature for 1 hour. A saturated sodium hydrogen carbonate aqueous solution was added to the reaction mixture, and the organic layer was separated, and the solvent was evaporated under reduced pressure. The obtained residue was purified with silica gel column chromatography [Flash Tube 2008 manufactured by Trikonex Company, eluent; hexane; ethyl acetate=4.1] to obtain tert-butyl 4-phenethyl-2-(3-phenyl-1H-pyrazole-5-carboxamido)benzoate.
