Sodium Thiosulfate → (S)-2-acetylthio-3-phenylpropanoic acid

Potassium thioacetate (68 mg, 0.64 mmol) was added to a solution of 100 mg (0.54 mmol) of the (2R)-2-chloro-3-phenylpropionic acid obtained in Example 14 in 2 ml of dimethylformamide at room temperature, and the mixture was stirred for 24 hours. A 6% aqueous solution of sodium thiosulfate (0.5 ml) was added to the reaction mixture, and the whole mixture was extracted with 30 ml of ethyl acetate. The organic phase was washed with 3 ml of 6% sodium thiosulfate aqueous solution, 3 ml of water and 3 ml of a saturated aqueous solution of sodium chloride, and dried over sodium sulfate. The solvent was removed under reduced pressure to give 101 mg (yield 83%) of the desired (2S)-2-acetylthio-3-phenylpropionic acid.