反应详情

To 14.8 g (47.3 mmol) racemic (2S,3R and 2R,3S)-2-dibenzylamino-3-hydroxy-pentanoic acid in 90 ml dimethylformamide were added at 0° C. 8.26 g (189 mmol) sodium hydride (55%). The suspension was stirred for 2 hours and then 10.4 ml (94.6 mmol) 2,5-difluoro-nitrobenzene in 10 ml dimethylformamide were added. After stirring overnight the mixture was poured under cooling on aqueous 2M citric acid solution. Extraction with ethylacetate and chromatography on silicagel with ethylacetate/heptane (3:7) yielded 12.9 g (61%) racemic (2S,3R and 2R,3S)-2-dibenzylamino-3-(4-fluoro-2-nitro-phenoxy)-pentanoic acid as orange solid, MS m/e (%): 453.0 (M+H+, 100).

1. stirringAfter stirring overnight the mixture
2. additionwas poured
3. extractionExtraction with ethylacetate and chromatography on silicagel with ethylacetate/heptane (3:7)