Hydrochloric Acid → (S)-2-acetylthio-3-phenylpropanoic acid

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Reaction Steps

The (2R)-2-chloro-3-phenylpropionic acid obtained in Example 13, 20.0 g (108.0 ml), to a mixture of 16.1 g (141.0 mmol) of potassium thioacetate and 40 ml of dimethylformamide was added dropwise at 0° C. and the mixture was stirred at room temperature for 24 hours. To the reaction mixture were added 60 ml of 6% sodium thiosulfate aqueous solution and 200 ml of toluene. The mixture was then adjusted to pH 1.7 with 35% aqueous hydrochloric acid and, after phase separation, the organic phase was recovered. This organic phase was washed with 60 ml of a 6% aqueous solution of sodium thiosulfate, 60 ml of a saturated aqueous solution of sodium chloride and 60 ml of water. The solvent was distilled off under reduced pressure to give 20.7 g (91.8 mmol, yield 85%) of the desired (2S)-2-acetylthio-3-phenylpropionic acid. The optical purity of the product as determined by the same method as in Example 18 was 98.9% ee (S) (configurational inversion rate 99.1%).

Provenance & Evidence