To a solution of ethyl 3-cyclopropyl-3-(3-((N-(2′-fluoro-5′-methoxy-2-neopentyl-[1,1′-biphenyl]-4-yl)-2-nitrophenylsulfonamido)methyl)phenyl)propanoate (1.22 g) in DMF (35 mL) were added mercaptoacetic acid (617 μL) and lithium hydroxide monohydrate (728 mg) at room temperature, and the mixture was stirred at 60° C. for 1 hr. To the reaction mixture was added saturated aqueous sodium hydrogen carbonate solution at 0° C., and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography (NH, ethyl acetate/hexane) to give the title compound (801 mg) as a colorless oil.
