[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[C:14]3[CH:15]=[C:16]([O:19][CH3:20])[CH:17]=[CH:18][C:13]=3[NH:12][C:11](=[S:21])[C@H:10]([CH2:22][C:23]([O:25]C)=[O:24])[N:9]=2)=[CH:4][CH:3]=1.[OH-].[Na+]>O1CCOCC1>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[C:14]3[CH:15]=[C:16]([O:19][CH3:20])[CH:17]=[CH:18][C:13]=3[NH:12][C:11](=[S:21])[CH:10]([CH2:22][C:23]([OH:25])=[O:24])[N:9]=2)=[CH:6][CH:7]=1To a solution of racemic Intermediate 6 (2.6 g, 6.7 mmol) in 1,4-dioxane (70 mL) at RT was added slowly 1N NaOH (13.5 mL) and the reaction mixture was stirred overnight before adding another 1N NaOH (13.5 mL). The mixture was then further stirred for 2 h before 1,4-dioxane was removed in vacuo. The aqueous layer was acidified with 1N HCl to ca pH 6 and extracted with DCM. The organics were dried over Na2SO4, filtered and concentrated under reduced pressure to give the title compound (1.9 g, 76% yield) as a yellow solid. LC/MS: m/z 375 [M(35Cl)+H]+, Rt=1.6 min.
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