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

Participants

Reaction Conditions

Reaction Steps

N-(tert-Butoxycarbonyl)-L-aspartic acid 4-benzyl ester (30 g) was dissolved in dimethoxyethane (90 mL) and the solution was cooled to −5° C. N-Methylmorpholine (10.32 mL) was added followed by isobutyl chloroformate (12.7 mL) in such a way to keep the temperature below −10° C. The mixture was aged for 0.5 hour. The solids were quickly filtered and washed with dimethoxyethane (90 mL). To the filtrate cooled to −50° C. was carefully added sodium borohydride (4.4 g) as a solution in water (45 mL) in such a way to keep the temperature between −30° C. and −15° C. After all the hydride had been added, water (500 mL) was added in such a way to maintain the temperature below −15° C. The suspension was filtered, the solid washed with water (400 mL) and dried to yield benzyl (3S)-3-[(tert-butoxycarbonyl)amino]-4-hydroxybutanoate.

Provenance & Evidence