Trifluoroacetic acid → rac-(2'S,3'R,4'S,5'R)-6-chloro-4'-(3-chloro-2-fluoro-phenyl)-2'-(2,2-dimethyl-propyl)-2-oxo-1,2-dihydro-spiro[indole-3,3'-pyrrolidine]-5'-carboxylic acid (1-methyl-1H-pyrrol-2-yl)-amide

A solution of rac-5-{[(2′S,3′R,4′S,5′R)-6-chloro-4′-(3-chloro-2-fluoro-phenyl)-2′-(2,2-dimethyl-propyl)-2-oxo-1,2-dihydro-spiro[indole-3,3′-pyrrolidine]-5′-carbonyl]amino}-1-methyl-1H-pyrrole-2-carboxylic acid tert-butyl ester (0.1 g, 0.16 mmol) in dichloromethane (2 mL) was added trifluoroacetic acid (2 mL). The reaction mixture was stirred at room temperature for 20 h, then concentrated. To the residue was added aqueous saturated NaHCO3 solution until “pH” became 7-8, and the mixture was extracted with ethyl acetate several times. The combined organic extract was washed with water, brine, dried over MgSO4, and concentrated to give rac-(2′S,3′R,4′S,5′R)-6-chloro-4′-(3-chloro-2-fluoro-phenyl)-2′-(2,2-dimethyl-propyl)-2-oxo-1,2-dihydro-spiro[indole-3,3′-pyrrolidine]-5′-carboxylic acid (1-methyl-1H-pyrrol-2-yl)-amide as a light brown solid (95 mg, 93%).