Hydrochloric Acid → (3S)-3-([(1,1-dimethylethyl)oxy]carbonylamino)-2-hydroxy-4-phenylbutyl ethanoate

Participants

Reaction Conditions

Reaction Steps

To a suitable reactor was added the crude 3a in EtOH solution (about 153 mL) reserved from the previous step at 20-30° C. under N2. The mixture was cooled to −25 to −15° C., and NaBH4 (2.35 g) in water (60 mL) was added at below −8° C. The reaction mixture was warmed to −5-5° C. and stirred for 1 hr. The reaction was deemed completed as determined by TLC. 1N HCl aqueous solution (60 mL) was added at below 10° C. The mixture was warmed to 20-30° C., and H2O (183 mL) was added at this temperature. After being stirred at 20-30° C. for 1 hr, the mixture was further cooled to 0-5° C. and stirred for 1 hr. The mixture was filtered, and the filtered cake was washed with cold 50% EtOH aqueous solution (30 mL). The combined filtrate and washing was concentrated at 40-50° C. under reduced pressure to afford crude 4a as a white powder (18.7 g).

Provenance & Evidence