反应详情

To a solution of 2,2,6,6-tetramethylthiopyran-3,5-dione (prepared according to the procedure of E. Er and P. Margaretha, Helvetica Chimica Acta (1992), 75(7), 2265-69) (1.8 g, 9.9 mmol) and N,N-dimethylaminopyridine (5.3 g, 4.34 mmol) in chloroform (60 ml), is added toluene (18 ml) then 5-bromo-2-ethylphenyllead triacetate (6.2 g, 1.09 mmol) in one portion. The resulting mixture is heated at reflux for 2 hours, then allowed to cool to ambient temperature, diluted with dichloromethane and 1M aqueous hydrochloric acid, and the organic phase is separated. The organic phase is concentrated under reduced pressure, and the residue is purified by flash chromatography on silica gel (hexane/ethyl acetate 95:5 to 7:3 ratio), giving 4-(5-bromo-2-ethylphenyl)-2,2,6,6-tetramethylthiopyran-3,5-dione (2.42 g) as an orange solid.

1. temperatureThe resulting mixture is heated
2. temperatureat reflux for 2 hours
3. customthe organic phase is separated
4. concentrationThe organic phase is concentrated under reduced pressure
5. customthe residue is purified by flash chromatography on silica gel (hexane/ethyl acetate 95:5 to 7:3 ratio)