[SH:1][C:2]1[S:3][C:4]([CH2:8][C:9]([OH:11])=[O:10])=[C:5]([CH3:7])[N:6]=1.[C:12]([O:16][C:17](=[O:22])[C:18](Br)([CH3:20])[CH3:19])([CH3:15])([CH3:14])[CH3:13]>CO.[OH-].[Na+]>[C:12]([O:16][C:17](=[O:22])[C:18]([S:1][C:2]1[S:3][C:4]([CH2:8][C:9]([OH:11])=[O:10])=[C:5]([CH3:7])[N:6]=1)([CH3:20])[CH3:19])([CH3:15])([CH3:14])[CH3:13]Commercially available (2-mercapto-4-methyl-1,3-thiazol-5-yl)acetic acid (15 g) was dissolved in methanol (360 mL) and 1N aqueous sodium hydroxide solution (174 mL), 2-bromo-2-methylpropionic acid tert-butyl ester (19.4 g) was added, and the mixture was stirred at 60° C. for 6 hr. The reaction mixture was concentrated, the residue was dissolved in water, and the mixture was acidified with 10% aqueous citric acid solution. The precipitated solid was collected by filtration, and dried under reduced pressure to give the title compound (25 g) as a white solid.
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