4-Methylmorpholine → Phenylmethyl (3S)-3-[[(1,1-dimethylethoxy)carbonyl]amino]-4-hydroxybutanoate

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Reaction Steps

(S)-2-t-butoxycarbonylamino-succinic acid 4-benzyl ester (545 mg, 1.69 mmol) was dissolved in tetrahydrofuran (THF) to which N-methylmorpholine (NMM, 0.19 mL, 1.77 mmol) and isobutyl chloroformate (0.23 mL, 1.77 mmol) were added at 0° C., followed by stirring at that temperature for 30 min. After 30 min, the resulting white solid salt was removed by celite filtration, and a solution of sodium borohydride (96 mg, 2.53 mmol) in distilled water (2 mL) was added to the resulting clear filtrate without further concentration at room temperature. After stirring for 1 hour at room temperature, THF was distilled under reduced pressure. The reaction was diluted with ethyl acetate and was terminated by the addition of 1N HCl. The organic layer was extracted with ethyl acetate and was purified by column chromatography (ethyl acetate:hexane=1:1) to afford 468 mg (yield: 90%) of the title compound.

Provenance & Evidence