Triethylamine → N-tert-butoxycarbonyl-3(S)-amino-2(R)-hydroxy-4-phenyl-1-methane sulfonyloxybutane

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Reaction Conditions

Reaction Steps

N-tert-butoxycarbonyl-3(S)-amino-2(R)-hydroxy-4-phenyl-butyric acid methyl ester 340.4 kg was reduced with sodium borohydride by the same way as described in Reference Example 3, to obtain the crude N-tert-butoxycarbonyl-3(S)-amino-2(R)-hydroxy-4-phenyl-1-butanol, which was dissolved in ethyl acetate 988 kg. To the solution were added methane sulfonylchloride 130.7 kg at 15-0° C. and triethylamine 115.4 kg, successively, and the solution was stirred at 20-30° C. for 15 min. The reaction solution was washed with aqueous 5% sodium bicarbonate solution to separate an organic phase, which was washed with aqueous 10% sodium chloride solution. The separated organic phase was mixed with n-heptane and cooled gradually down to 5° C. or lower to deposit crystals, which were filtered by a Nutsche funnel to obtain a wet crystal of crude N-tert-butoxycarbonyl-3(S)-amino-2(R)-hydroxy-4-phenyl-1-methanesulfonyloxybutane 793 kg (Net.368.9 kg).

Provenance & Evidence