[Br:1][C:2]1[CH:7]=[CH:6][C:5]([NH:8][C@@H:9]([CH3:13])[CH2:10][C:11]#[N:12])=[CH:4][CH:3]=1.[OH:14]S(O)(=O)=O>C1(C)C=CC=CC=1.O>[Br:1][C:2]1[CH:3]=[CH:4][C:5]([NH:8][C@@H:9]([CH3:13])[CH2:10][C:11]([NH2:12])=[O:14])=[CH:6][CH:7]=1(3S)-3-[(4-Bromophenyl)amino]butanenitrile (for a preparation see Intermediate 104) (17.3 g, 72.4 mmol) was taken up in toluene (500 ml) and H2SO4 (19.28 ml, 362 mmol) added. The biphasic mixture was stirred at 60° C. After two hours, only a small amount of starting material remained by LCMS so the reaction was diluted with water (500 mL) and the phases separated. The aqueous phase was basified with 10N NaOH and extracted with EtOAc (2×750 mL). The combined organics were dried with Na2SO4, filtered and concentrated to yield the product as a cream solid (17.5 g).
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