反应详情

To a mixture of 5-bromo-2-fluoroaniline (4.15 g), methyl 3-mercaptopropionate (2.62 g), 4,5-bis (diphenylphosphino) -9,9-dimethylxanthene (0.63 g) and N,N-diisopropylethylamine (5.64 g) in 1,4-dioxane (80 mL) was added tris (dibenzylidene -acetone) dipalladium(0) (0.3 g), and the mixture was heated for reflux under an argon atmosphere overnight. The insoluble material was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (eluent: n-hexane/ethyl acetate=20/1−5/1−2/1) to give 2-fluoro-5-(2-methoxy -carbonylethylthio)aniline (4.62 g). This material was dissolved in tetrahydrofuran (120 mL). To the solution was added potassium tert-butoxide (1 mol/L tetrahydrofuran solution, 80.6 mL) at −78° C., and the mixture was stirred at the same temperature for 15 minutes. To the reaction mixture was added 1 mol/L hydrochloric acid (81 mL), and the mixture was warmed to room temperature and stirred for 5 minutes. The mixture was poured into ethyl acetate, and the organic layer was separated. The organic layer was washed with brine and dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure, and the residue was purified by column chromatography on silica gel (eluent: n-hexane/ethyl acetate=4/1) to give the title compound (1.85 g).

1. temperaturethe mixture was heated
2. temperaturefor reflux under an argon atmosphere overnight
3. customThe insoluble material was removed by filtration
4. concentrationthe filtrate was concentrated under reduced pressure
5. customThe residue was purified by column chromatography on silica gel (eluent: n-hexane/ethyl acetate=20/1−5/1−2/1)