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

Participants

Reaction Conditions

Reaction Steps

A 5 L 3-neck round bottom flask was charged with L-serine (313 g, 3.0 mol) and 2N sodium hydroxide solution (1.5 L). Stirring was begun and benzaldehyde (322.4 g, 3.0 mol) added. After 15 minutes at room temperature the solution was cooled to 5° C. and sodium borohydride (35.0 g, 0.93 mol) was added in small portions so as to maintain the temperature below 10° C. Once the addition was complete the solution was allowed to warm to room temperature and stir for 2 h. At this point, a second portion of benzaldehyde (322.4 g, 3.0 mol) was added and the solution stirred for 15 minutes. The solution was cooled to 5° C. and sodium borohydride (35.0 g, 0.93 mol) added, again maintaining the temperature below 10° C. The reaction mixture was then warmed to room temperature and stirred for 2 h. Diethyl ether (1 L) was added, the solution stirred 5-10 minutes and the ether layer separated. The pH of the aqueous layer was then adjusted to 6 with 37% hydrochloric acid. Filtration of the resulting solids and recrystallization of the wet cake from water afforded 230 g (40%) of (S)-(+)-N-benzylserine after drying at 45° C. overnight.

Provenance & Evidence