反应详情

A mixture of 5-Formylbenzofurazan (0.6 g, 4.1 mmol), methyl acetoacetate (0.52 g, 4.5 mmol), piperidine (0.019 g, 0.225 mmol), and acetic acid (0.014 g, 0.225 mmol) in benzene (30 mL) was stirred and refluxed with a Dean-Stark trap for 8 h. Benzene was evaporated, the residue was dissolved in ethyl acetate (80 mL) and washed with brine (50 mL), saturated potassium bisulfate solution (50 mL), and saturated sodium bicarbonate solution in sequence. The ethyl acetate solution was dried (magnesium sulfate), solvent removed under reduced pressure and the residue was purified by column chromatography (SiO2, EtOAc/hexane, 10%-15%). The product, methyl 2{(benzofuran-5-yl)methylene}-3-oxobutyrate, was obtained as an oil (0.98 g, 98.3%) and was used in the next step without any further characterization.

1. temperaturerefluxed with a Dean-Stark trap for 8 h
2. customBenzene was evaporated
3. dissolutionthe residue was dissolved in ethyl acetate (80 mL)
4. washwashed with brine (50 mL), saturated potassium bisulfate solution (50 mL), and saturated sodium bicarbonate solution in sequence
5. dry with materialThe ethyl acetate solution was dried (magnesium sulfate), solvent
6. customremoved under reduced pressure
7. customthe residue was purified by column chromatography (SiO2, EtOAc/hexane, 10%-15%)