[C:1]([O:5][C:6]([NH:8][CH2:9][CH2:10][O:11][C:12]1[CH:21]=[C:20]([S:22]([CH3:25])(=[O:24])=[O:23])[CH:19]=[CH:18][C:13]=1[C:14]([O:16]C)=[O:15])=[O:7])([CH3:4])([CH3:3])[CH3:2].CCO.[OH-].[K+]>O>[C:1]([O:5][C:6]([NH:8][CH2:9][CH2:10][O:11][C:12]1[CH:21]=[C:20]([S:22]([CH3:25])(=[O:24])=[O:23])[CH:19]=[CH:18][C:13]=1[C:14]([OH:16])=[O:15])=[O:7])([CH3:4])([CH3:3])[CH3:2]A mixture of methyl 2-(2-t-butoxycarbonylaminoethoxy)-4-methylsulfonylbenzoate (8.6 g, 23 mmol), EtOH (200 mL), and KOH (6.5 g, 115 mmol) in water (200 mL) was heated to 70° C. for 4 hours. The EtOH was removed in vacuo and the residue was diluted with CH2Cl2. The mixture was acidified with satd citric acid and partitioned. The organic layer was dried (Na2SO4) and concentrated to give the desired product as a solid (7.5 g, 91%).
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