反应详情

10.0 g (29.7 mmol) of the dithioacetal 6 are dissolved in 100 ml of dichloro-methane, and 2.6 ml (30.0 mmol) of trifluoromethanesulfonic acid are added dropwise with ice/common salt cooling. After 5 minutes, the cooling is removed, and the batch is stirred at room temperature for 45 minutes. The batch is subsequently cooled to −70° C., a mixture of 7.5 ml (54.0 mmol) of triethylamine and 6.67 g (45.0 mmol) of trifluorophenol in 30 ml of dichloromethane is added, and the mixture is stirred at −70° C. for 1 hour. 24.2 ml (0.150 mol) of triethylamine tris(hydrofluoride) are then added, and, after 5 minutes, 42.9 g (0.150 mol) of DBH, suspended in 60 ml of dichloromethane, are added in portions over the course of about 30 minutes. After 90 minutes, the batch is allowed to thaw and is hydro-lysed using 1 M sodium hydroxide solution and aqueous hydrogen sulfite solution. The organic phase is separated off, washed with saturated sodium chloride solution and dried over sodium sulfate. The solvent is removed under reduced pressure, and the residue is filtered through silica gel with n-heptane, giving the spiro compound 7 as a colourless solid of melting point: 43° C.

1. temperaturecooling
2. customthe cooling is removed
3. temperatureThe batch is subsequently cooled to −70° C.
4. additionis added
5. stirringthe mixture is stirred at −70° C. for 1 hour
6. waitafter 5 minutes
7. additionare added in portions over the course of about 30 minutes
8. waitAfter 90 minutes
9. customThe organic phase is separated off
10. washwashed with saturated sodium chloride solution
11. dry with materialdried over sodium sulfate
12. customThe solvent is removed under reduced pressure
13. filtrationthe residue is filtered through silica gel with n-heptane