5-isopropyl-2,4-bis(methoxymethoxy)-benzoic acid (IM3-a: 16.4 g, 54.5 mmol), 4-methoxyphenylthiosemicarbazide (F53-02: 11.3 g, 57.3 mmol), dimethylformamide (150 mL) and 1-hydroxybenzotriazole monohydrate (8.11 g, 60.0 mmol) were placed in a 500 mL eggplant shaped flask. The reaction mixture was cooled to 0° C. and mixed with a suspension of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (11.5 g, 60 mmol) in dimethylformamide (100 mL). The mixture was stirred for 4 hours and allowed to come to room temperature. After completing the reaction, saturated sodium chloride solution (500 mL) was added to the reaction mixture, and the mixture was extracted twice with ethyl acetate (500 mL). The organic layer thus obtained was washed 4 times with saturated sodium chloride solution (500 mL) and dried over anhydrous sodium sulfate. After removing sodium sulfate by filtration, the solvent was distilled under reduced pressure, and the solids obtained were suspended in hexane (1000 mL) for purification and collected by filtration. The solids thus obtained were dried under reduced pressure to obtain the title compound (F53-03: 21.9 g, 83.8%).
