Ammonia chloride → 2-{[4-(2-Hydroxyethyl)-1,3-thiazol-2-yl]thio}-2-methylpropionic acid tert-butyl ester

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Reaction Steps

{2-[(2-tert-Butoxy-1,1-dimethyl-2-oxoethyl)thio]-1,3-thiazol-4-yl}acetic acid (127 g) synthesized in Example 3 was added to 1M-borane/tetrahydrofuran complex (800 mL) under ice-cooling, and the mixture was stirred at room temperature for 8 hr. The reaction mixture was ice-cooled, methanol (400 mL) was added dropwise. After warming to room temperature, the mixture was stirred for 1 hr. Then, saturated aqueous ammonia chloride (300 mL) was added, and the mixture was stirred at room temperature for 1 hr. The reaction mixture was concentrated under reduced pressure, poured into water, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel chromatography (elution solvent; hexane:ethyl acetate=1:1) to give the title compound (110 g) as a slightly yellow oil.

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