反应详情

1.30 g (4.00 mmol) racemic (2R,3S and 2S,3R)-3-Cyclopropyl-2-dibenzylamino-3-hydroxy-propionic acid in 4 ml dimethylformamide were added at 0° C. to 0.37 g (8.48 mmol) sodium hydride (55%) in 4 ml dimethylformamide. The suspension was stirred for 2 hours and then 0.96 ml (8.8 mmol) 2,5-difluoro-nitrobenzene in 3.4 ml dimethylformamide were added. After stirring overnight 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 diethylether/heptane (25:75 to 100:0) yielded 1.57 g (85%) racemic (2R,3S and 2S,3R)-3-cyclopropyl-2-dibenzylamino-3-(4-fluoro-2-nitro-phenoxy)-propionic acid as light yellow foam, MS m/e (%): 465.0 (M+H+, 100).

1. stirringAfter stirring overnight the mixture
2. additionwas poured on ice/water
3. extractionExtraction with ethylacetate and chromatography on silicagel with diethylether/heptane (25:75 to 100:0)