Potassium carbonate (0.033 mg) and isopropyl iodide (0.024 mL) were sequentially added to an acetonitrile (1.9 mL) suspension of methyl 2-(2-(benzyloxy)-5-(piperidin-4-yl)benzamido)-4-phenylbenzoate (0.13 g), followed by heating to reflux for 1 hour. The reaction mixture was cooled to room temperature, and potassium carbonate (6.7 mg) and isopropyl iodide (4.8 μL) were sequentially added thereto, followed by heating to reflux for 2 hours. After cooling the reaction mixture to room temperature, the solvent was evaporated under reduced pressure, and ethyl acetate and a saturated aqueous solution of sodium bicarbonate were added to the residue. The organic layer was separated, washed with a saturated aqueous solution of sodium chloride, and dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography [eluent: 100-95% chloroform/methanol] to obtain 0.12 g of methyl 2-(2-(benzyloxy)-5-(1-isopropylpiperidin-4-yl)benzamido)-4-phenylbenzoate as an orange oily sub stance.
