反应详情

A solution of commercially available reagent of tert-butyl [1,3]dithiane-2-carboxylate (2.0 g, 9.69 mmol) in THF (20 mL) was cooled to −78° C., and n-butyl lithium (1.67 M solution in n-hexane, 8.62 mL, 13.6 mmol) was then added over 10 minutes. The mixture was stirred for 80 minutes, and 2-fluoro-ethyl toluene-4-sulfonate (2.95 g, 13.5 mmol, known compound, ref. Tetrahedron (2005), 61 (35), 8410-8418) was then added. The mixture was stirred at −78° C. for 30 minutes, and the cooling bath was then removed. The mixture was stirred while allowing the temperature to gradually return to room temperature, and stirred at room temperature for 20 hours. After confirming the consumption of the starting materials by LCMS, the mixture was quenched with water (100 mL), and then extracted with dichloromethane (100 mL). The aqueous layer was further extracted with dichloromethane (50 mL). The combined dichloromethane layer was washed with a saturated aqueous solution (100 mL) of ammonium chloride and a saturated aqueous solution (100 mL) of sodium chloride in this order, then dried over anhydrous sodium sulfate, and filtered. The organic layer was concentrated under reduced pressure. The resulting residue was purified on Biotage (silica gel, n-hexane/ethyl acetate) to obtain tert-butyl 2-(2-fluoro-ethyl)-[1,3]dithiane-2-carboxylate (2.79 g, quant.).

1. stirringThe mixture was stirred at −78° C. for 30 minutes
2. customthe cooling bath was then removed
3. stirringThe mixture was stirred
4. customto gradually return to room temperature
5. stirringstirred at room temperature for 20 hours
6. customthe consumption of the starting materials by LCMS
7. customthe mixture was quenched with water (100 mL)
8. extractionextracted with dichloromethane (100 mL)
9. extractionThe aqueous layer was further extracted with dichloromethane (50 mL)
10. washThe combined dichloromethane layer was washed with a saturated aqueous solution (100 mL) of ammonium chloride
11. dry with materiala saturated aqueous solution (100 mL) of sodium chloride in this order, then dried over anhydrous sodium sulfate
12. filtrationfiltered
13. concentrationThe organic layer was concentrated under reduced pressure
14. customThe resulting residue was purified on Biotage (silica gel, n-hexane/ethyl acetate)