A mixture of 3-[4-({(2E)-3-[5-(4-fluorophenyl)-1-methyl-1H-pyrazol-4-yl]prop-2-enoyl}amino)phenyl]-2-hydroxypropionic acid (409 mg), ethyl chlorocarbonate (324 mg), triethylamine (405 mg) and ethyl acetate (10 ml) was stirred at 0° C. for 1 hr. Conc. aqueous ammonia (10 ml) was added to the reaction mixture and the mixture was stirred at room temperature for 1 hr. The reaction mixture was concentrated, and the precipitated solids were collected by filtration, washed with water and dried to give 2-(ethoxycarbonyloxy)-3-[4-({(2E)-3-[5-(4-fluorophenyl)-1-methyl-1H-pyrazol-4-yl]prop-2-enoyl}amino)phenyl]propionamide (471 mg, 98%) as colorless crystals.
