To a solution of (2S,4R)-methyl 4-(biphenyl-4-yl)-1-((S)-2-(tert-butoxycarbonylamino)-3,3-dimethylbutanoyl)-4-(methylthio)pyrrolidine-2-carboxylate (164 mg, 0.303 mmol) in THF (2 mL) and MeOH (2.000 mL) was added pre-made solution of Lithium hydroxide monohydrate (25.5 mg, 0.607 mmol) in water (2 mL). The resulting cloudy solution was stirred at room temperature overnight. Quenched with 5% citric acid, extracted with EtOAc. The organic layer was washed with brine, dried over MgSO4, filtered, evaporated, to afford the desired product (2S,4R)-4-(biphenyl-4-yl)-1-((S)-2-(tert-butoxycarbonylamino)-3,3-dimethylbutanoyl)-4-(methylthio)pyrrolidine-2-carboxylic acid (136 mg, 0.232 mmol, 77% yield) as a white foam. LC-MS (retention time: 3.25 min, method B), MS m/z 527 (M+H).
