Citric Acid → (2S,3S)-(-)-3-tert-Butoxycarbonylamino-1,2-epoxy-4-phenylbutane

Participants

Reaction Conditions

Reaction Steps

(2S,3S)-3-tert-butoxycarbonylamino-1-chloro-2-hydroxy-4-phenylbutane (5.29 g) and potassium carbonate (4.88 g) were added to an ethanol:water (97:3) mixed solution (106 ml). The mixture was stirred at 33° C. for 7 hours, and a 10% citric acid aqueous solution(67.8 g)was added there to. After ethanol was distilled off under reduced pressure, toluene (93 ml) was added to conduct extraction. Further, the organic layer was washed with water (93 ml), and then concentrated. To the residue was added a heptane:toluene (4:1) mixture (112 ml). The heating was conducted at 50° C. over 1 hour, and the stirring was further conducted at 50° C. for 1 hour. Subsequently, cooling was conducted to −10° C. over 5 hours, and stirring was further conducted at −10° C. for 8 hours. Crystals were collected by filtration, washed with heptane, and then dried under reduced pressure to obtain desired (2S,3S)-3-tert-butoxycarbonylamino-1,2-epoxy-4-phenylbutane (4.39 g) in a yield of 95%.

Provenance & Evidence