Ethanolamine → (S)-2-amino-N-(2-hydroxyethyl)-3,3-dimethylbutanamide

Participants

Reaction Conditions

Reaction Steps

To a solution of Cbz-tert-leucine dicyclohexylammonium salt (1.34 g, 3.0 mmol) and DIEA (0.7 ml) in DCM (25 mL) cooled in an ice-water bath was added isobutyl chloroformate (0.47 mL, 3.6 mmol). After stirring at 0° C. for 1 hour, ethanolamine was added (0.52 mL, 9.0 mmol) and stirred overnight. The reaction was quenched with saturated aqueous sodium bicarbonate. The organic phase was separated and dried over sodium sulfate. After evaporation under reduced pressure, the residue was dissolved in MeOH and passed through a SCX (Phenomenex®, Torrance, Calif.) cationic ion-exchange column to remove dicyclohexylamine and DIEA. The filtrate was evaporated and hydrogenated with Pd/C (0.5 g) under hydrogen at 45 psi in MeOH for 4 hours. Palladium catalyst was removed by filtration through celite. The filtrate was concentrated and dried under vacuum overnight to give intermediate 23 (0.35 g), which was used without further purification. LCMS (+ESI) m/z=175 [M+H]+.

Provenance & Evidence