Trifluoroacetic acid → (2S,4R)-methyl 4-(biphenyl-4-yl)-1-((S)-2-(tert-butoxycarbonylamino)-3,3-dimethylbutanoyl)-4-(isopropylthio)pyrrolidine-2-carboxylate

Participants

Reaction Steps

To an iced slurry of (2S,4R)-methyl 4-(biphenyl-4-yl)-4-(isopropylthio)pyrrolidine-2-carboxylate, TFA (255 mg, 0.543 mmol), (S)-2-(tert-butoxycarbonylamino)-3,3-dimethylbutanoic acid (138 mg, 0.597 mmol), and HATU (309 mg, 0.814 mmol) in DCM (8 mL) was added N,N-diisopropylethylamine (0.285 mL, 1.629 mmol). The formed colorless slurry was stirred at room temperature overnight. Diluted with DCM, quenched with 5% citric acid. The organic layer was washed with 0.1 M NaOH and brine, dried over MgSO4, filtered, evaporated in vacuo. The residue was purified by BIOTAGE® column, eluted with 5˜35% EtOAc-hexane to yield the desired product (2S,4R)-methyl 4-(biphenyl-4-yl)-1-((S)-2-(tert-butoxycarbonylamino)-3,3-dimethylbutanoyl)-4-(isopropylthio)pyrrolidine-2-carboxylate (240 mg, 0.380 mmol, 69.9% yield) as a white foam. 1H NMR (500 MHz, MeOD) ppm 1.06 (d, 3H), 1.09-1.13 (m, 12H), 1.48 (s, 9H), 2.48 (dd, J=12.82, 8.24 Hz, 1H), 2.53-2.62 (m, 1H), 2.97 (dd, J=12.51, 7.63 Hz, 1H), 3.73 (s, 3H), 4.03 (d, J=11.29 Hz, 1H), 4.25 (t, J=7.93 Hz, 1H), 4.45 (s, 1H), 4.88-4.91 (m, 1H), 7.36 (t, J=7.32 Hz, 1H), 7.45 (t, J=7.78 Hz, 2H), 7.58-7.73 (m, 6H). LC-MS (retention time: 3.50 min, method B), MS m/z 569 (M+H).

Provenance & Evidence