To a mixture of 8.2 mg of 7-methyl-4-oxo-1-(tetrahydro-2H-pyran-4-yl)-4,5-dihydro-1H-pyrazolo[4,3-c]quinoline-8-carboxylic acid, 7.7 mg of methyl 3-piperidin-4-yl-benzoate monohydrochloride, 3.4 mg of 1-hydroxybenzotriazole, 7.0 μL of triethylamine, and 1.0 mL of DMF was added 100 mg of PS-Carbodiimide (Biotage), followed by stirring at room temperature overnight. To the reaction mixture were added 75 mg of MP-Carbonate (Biotage), 50 mg of PS-Isocyanate (Biotage), and 0.5 mL of DMF at room temperature, followed by stirring for 2 hours. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure. To the obtained residue were added 0.5 mL of methanol, 0.5 mL of tetrahydrofuran, and 0.5 mL of a 1 M aqueous sodium hydroxide solution, followed by stirring at room temperature overnight. To the reaction mixture was added 0.5 mL of 1 M hydrochloric acid and the solvent was evaporated under reduced pressure. The obtained residue was purified by preparative HPLC (methanol/0.1% aqueous formic acid solution) to obtain 5.8 mg of 3-(1-{[7-methyl-4-oxo-1-(tetrahydro-2H-pyran-4-yl)-4,5-dihydro-1H-pyrazolo[4,3-c]quinolin-8-yl]carbonyl}piperidin-4-yl)benzoic acid.
