[OH-].[Na+].[Br:3][C:4]1[CH:5]=[C:6]2[C:10](=[C:11]([C:13]([O:15]C)=[O:14])[CH:12]=1)[N:9](C(OC(C)(C)C)=O)[CH:8]=[C:7]2[CH:24]1[CH2:29][CH2:28][S:27](=[O:31])(=[O:30])[CH2:26][CH2:25]1.BrC1C=C2C(=C(C(OCC)=O)C=1)N(C(OC(C)(C)C)=O)C=C2C1CCS(=O)(=O)CC1>CO.O>[Br:3][C:4]1[CH:5]=[C:6]2[C:10](=[C:11]([C:13]([OH:15])=[O:14])[CH:12]=1)[NH:9][CH:8]=[C:7]2[CH:24]1[CH2:25][CH2:26][S:27](=[O:30])(=[O:31])[CH2:28][CH2:29]1A solution of 6 M NaOH (12 mL, 72.0 mmol) was added to a suspension of 1-(1,1-dimethylethyl) 7-methyl 5-bromo-3-(1,1-dioxidotetrahydro-2H-thiopyran-4-yl)-1H-indole-1,7-dicarboxylate (0.93 g, 1.912 mmol) and 1-(1,1-dimethylethyl) 7-ethyl 5-bromo-3-(1,1-dioxidotetrahydro-2H-thiopyran-4-yl)-1H-indole-1,7-dicarboxylate (3.08 g, 6.16 mmol) in MeOH (50 mL) and water (25 mL) in a 250 mL round bottomed flask fitted with a reflux condenser. The reaction was heated at 85° C. (bath temp) for 1.5 h. The MeOH was removed by rotovap, and a solution of 6 M HCl was added until the mixture had attained a pH of ˜1 by pH paper. The yellow solid was filtered off, and the filtrate was extracted with EtOAc (3×10 mL). The combined organic layers were dried (Na2SO4) and concentrated under reduced pressure, and the residue was combined with the precipitate from the filtration and dried under house vacuum at 45° C. overnight. Recovered 2.98 g (86%) of the title compound.
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