Benzaldehyde → (2S)-2-(benzylamino)-3-hydroxypropanoic acid

Participants

Reaction Conditions

Reaction Steps

Racemic serine (14.7 g, 140 mmol) was dissolved in 2M NaOH (70 mL) and benzaldehyde (14.64 g, 14.0 mL, 138 mmol) added with stirring. The mixture was stirred at r.t. for 1 h before cooling to 5° C. Sodium borohydride (1.5 g, 40 mmol) was added portionwise such that an internal temperature of between 6 and 10° C. was maintained. After addition the reaction mixture was allowed to stir at 5° C. for 30 minutes and then at r.t. for 1 h. The reaction mixture was cooled to 5° C. and a further portion of sodium borohydride (1.5 g, 40 mmol) added portionwise such that an internal temperature <10° C. was maintained. The ice bath was removed on completion of addition and the reaction stirred at r.t. for 16 h. The reaction mixture was extracted with Et2O (3×100 mL) and the aqueous phase acidified to pH 5 with concentrated hydrochloric acid. The resultant white precipitate was filtered and washed with water. The product was dried in vacuo to give the title compound (24.0 g, 88%). δH (DMSO-d6) 7.45-7.30 (5H, m), 4.04-3.91 (2H, m), 3.70-3.61 (3H, m), 3.17 (1H, t, J 5.8 Hz). Some exchangeable protons were not observed.

Provenance & Evidence