At room temperature, tert-butyl 4-(4-(3-(4-chloro-3-(trifluoromethyl)phenyl)ureido)-3-fluorophenoxy)picolinate (1.8 g, 3.43 mmol) was dissolved in dichloromethane (15 mL). Trifluoroacetic acid (15 mL) and triethyl silane (0.2 mL) was added. The resulted mixture was heated to 50° C. and stirred for 16 h. The solvent was removed under reduced pressure. The residue was partitioned in water (50 mL) and ethyl acetate (50 mL), and separated. The organic phase was removed, and the aqueous layer was filtered. The solid was washed with water (20 mL×2) and dried in vacuum to give the title compound (1.48 g, purity 85%, yield 92%) as a grey solid.
