Reacción #11026

Ecuación de reacción

hydrochloric acid

sodium thiosulfate

(2R)-2-chloro-3-phenylpropionic acid

potassium thioacetate

→

(2S)-2-acetylthio-3-phenylpropionic acid

Rendimiento 85.0%

Disolventes

toluene

dimethylformamide

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONwas added dropwise at 0° C.
2. 2
   Otroafter phase separation
3. 3
   Otrothe organic phase was recovered
4. 4
   LavadoThis 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
5. 5
   workup.DISTILLATIONThe solvent was distilled off under reduced pressure

Procedimiento

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%).

Fuente