反应详情

In a round-bottomed flask, 2-((R)-1-tert-butoxycarbonylamino-ethyl)-4,5-dihydro-oxazole-4-carboxylic acid methyl ester (337 mg, 1.18 mmol) was dissolved in dichloromethane (11 ml). The solution was cooled to −16° C. (NaCl/ice bath) and DBU (0.35 ml, 2.32 mmol) was added. After 5 min, bromotrichloromethane (0.13 ml, 1.33 mmol) was added and the reaction mixture was allowed slowly to warm to room temperature and stirred for 4 days. The reaction was quenched with 0.1 M aqueous HCl and extracted with EtOAc (2×). The combined organic layers were washed with water and brine then dried over sodium sulfate, filtered and concentrated. The residue was chromatographed over silica gel with EtOAc/hexanes (gradient 0-30% EtOAc) to afford 152 mg (48%) of 2-((R)-1-tert-butoxycarbonylamino-ethyl)-oxazole-4-carboxylic acid methyl ester as an off-white solid.

1. additionwas added
2. customThe reaction was quenched with 0.1 M aqueous HCl
3. extractionextracted with EtOAc (2×)
4. washThe combined organic layers were washed with water and brine
5. dry with materialthen dried over sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated
8. customThe residue was chromatographed over silica gel with EtOAc/hexanes (gradient 0-30% EtOAc)