反应详情

温度

0 °C

To a solution of 1,1-dimethylethyl 4-[4,5-dihydro-4-(methoxycarbonyl)-2-oxazolyl]-1-piperidinecarboxylate (i.e. the product of Example 7, Step B) (2.89 g, 9.26 mmol) in 100 mL of dichloromethane at 0° C. was added 1.52 mL (10.18 mmol) of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and the reaction mixture was stirred for 10 minutes at 0° C. Bromotrichloromethane (1 mL, 10.18 mmol) was added dropwise over 7 minutes, and the reaction mixture was stirred for 6 h at 0° C. The mixture was washed with saturated aqueous ammonium chloride (2×50 mL), the aqueous phase was extracted with ethyl acetate (2×25 mL), and the combined organic layers were dried over magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel chromatography using 25-75% of ethyl acetate in hexanes as eluant to give 1.41 g of the title compound as white crystals.

1. stirringthe reaction mixture was stirred for 6 h at 0° C
2. washThe mixture was washed with saturated aqueous ammonium chloride (2×50 mL)
3. extractionthe aqueous phase was extracted with ethyl acetate (2×25 mL)
4. dry with materialthe combined organic layers were dried over magnesium sulfate
5. concentrationconcentrated under reduced pressure
6. customThe residue was purified by silica gel chromatography