反应详情

温度

-78 °C

A solution of tert-butyl 2-bromopyridin-3-ylcarbamate (3.85 g, 14 mmol) (prepared from the procedure used by Kowol etc, J. Med. Chem., 2009, 52, 5032-5043) in dry THF (20 mL) was cooled to −78° C. and was treated drop-wise with n-butyllithium (11.2 mL of 2.5M solution in hexane, 2.0 eq) such that the temperature never exceeded −65° C., and the resulting mixture was stirred at −78° C. for an additional hour. After drop-wise addition of diethyl oxalate (4 mL, 29 mmol, 2.1 eq), the reaction mixture was allowed to warm to 0° C., maintained there for 1 h, and then quenched by the addition of NH4Cl (40 mL). The resulting mixture was extracted with ethyl acetate (3×20 mL). The combined organic layers were washed with water (3×20 mL) and brine (20 mL). After drying, filtration, and evaporation, the residue was purified by column chromatography on silica gel with dichloromethane as eluant to afford ethyl 2-(3-(tert-butoxycarbonylamino)pyridin-2-yl)-2-oxoacetate as a white solid. Mass Spectrum (ESI) m/e=295 (M+1).

1. temperatureto warm to 0° C.
2. temperaturemaintained there for 1 h
3. customquenched by the addition of NH4Cl (40 mL)
4. extractionThe resulting mixture was extracted with ethyl acetate (3×20 mL)
5. washThe combined organic layers were washed with water (3×20 mL) and brine (20 mL)
6. customAfter drying
7. filtrationfiltration, and evaporation
8. customthe residue was purified by column chromatography on silica gel with dichloromethane as eluant