反应详情

A solution of 20 g (70.6 mmol) dibenzylamino-acetic acid ethyl ester in 240 ml tetrahydrofuran was stirred at −78° C. with 38.8 ml (77.6 mmol) lithium diisopropylamide (2M in heptane) for 30 minutes. 5.83 ml (77.6 mmol) Propionaldehyde in 5 ml tetrahydrofurane were added and stirring was continued overnight. The mixture was allowed to warm to room temprature, water was added and most of the organic solvent was removed by distillation. Extraction with ethylacetate and chromatography on silicagel with ethylacetate/heptane 1/5 yielded as first eluting fraction 6.85 g (28%) racemic (2S,3R and 2R,3S)-2-dibenzylamino-3-hydroxy-pentanoic acid ethyl ester, MS m/e (%): 342.3 (M+H+, 100) and as second eluting fraction 6.15 g (26%) racemic (2R,3R and 2S,3S)-2-dibenzylamino-3-hydroxy-pentanoic acid ethyl ester, MS m/e (%): 342.2 (M+H+, 100).

1. additionwas added and most of the organic solvent
2. customwas removed by distillation
3. extractionExtraction with ethylacetate and chromatography on silicagel with ethylacetate/heptane 1/5