反应详情

3.50 g (9.32 mmol) racemic (2S,3R and 2R,3S)-2-dibenzylamino-3-hydroxy-4-phenyl-butyric acid in 14 ml dimethylformamide were added at 0° C. to 0.86 g (19.8 mmol) sodium hydride (55%) in 2 ml dimethylformamide. The suspension was stirred for 2 hours and then 2.25 ml (20.5 mmol) 2,5-difluoro-nitrobenzene in 3.4 ml dimethylformamide were added. After stirring overnight at 0° C. the mixture was poured on ice/water. The pH was adjusted to 1 by adding aqueous hydrochloric acid. Extraction with ethylacetate and chromatography on silicagel with dichloromethane/methanol (100:0 to 95:5) yielded 2.95 g (62%) racemic (2S,3R and 2R,3S)-2-dibenzylamino-3-(4-fluoro-2-nitro-phenoxy)-4-phenyl-butyric acid as yellow oil, MS m/e (%): 515.3 (M+H+, 100).

1. stirringAfter stirring overnight at 0° C. the mixture
2. additionwas poured on ice/water
3. extractionExtraction with ethylacetate and chromatography on silicagel with dichloromethane/methanol (100:0 to 95:5)