反应详情

To a stirred suspension of tert-butyl 2-(2-methoxy-2-oxoethyl)-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylate (5.3 g, 17.3 mmol) in toluene (50 mL) 1,4-cyclohexandione (2.8 g, 25 mmol) and p-toluenesulfonic acid (1 g) were added. The resulting solution was stirred at reflux for 4 hours, using a condenser equipped with a Dean-Stark apparatus. The reaction mixture was concentrated in vacuo. The remaining oil was purified by flash chromatography on silica gel column eluting with ethyl acetate to give 2-(2-methoxy-2-oxoethyl)-4-phenyl-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylic acid (2.9 g, 52%) as a white solid.

1. additionwere added
2. temperatureat reflux for 4 hours
3. customequipped with a Dean-Stark apparatus
4. concentrationThe reaction mixture was concentrated in vacuo
5. customThe remaining oil was purified by flash chromatography on silica gel column
6. washeluting with ethyl acetate