Citric Acid → (2S,3S)-1,2-Epoxy-3-(Cbz-amino)-4-phenylbutane

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Reaction Steps

To a suspension of 196.7 g of the N-benzyloxycarbonyl-3(S)-amino-2(R)-methanesulfonyloxy-4-phenyl-1-butanol obtained in the above Example 3 in 2,500 ml of methanol was added 90 g of potassium carbonate. The obtained mixture was then stirred at room temperature for 5 hours. The pH value of the reaction mixture was adjusted to 7 with a 10% aqueous solution of citric acid. Then the solvent was concentrated under reduced pressure. After adding water to the residue, it was extracted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride. After adding anhydrous sodium sulfate and activated carbon, the mixture was filtered. Then the filtrate was concentrated and n-hexane was added thereto for crystallization. The crystals thus precipitated were filtered and dried. Thus the target N-benzyloxycarbonyl-3(S)-amino-1,2(S)-epoxy-4-phenylbutane was obtained in the form of white crystals. The overall yield of Referential Example 2 and Example 3 through Example 4 was 72.3%.

Provenance & Evidence