反应详情

温度

0 °C

To a solution of diisopropylamine (6.05 mL, 43.2 mmol) and HMPA (7.52 mL, 43.2 mmol) in anhydrous THF (40 mL) at −78° C. under argon was added n-butyllithium (27 mL of 1.6 M in hexanes, 43.2 mmol). The mixture was stirred at 0° C. for 1 h and then cooled to −78° C. To this solution were added dropwise via transfer needles a cold (−78° C.) solution of diethyl (difluoromethyl)phosphonate (6.8 mL, 43.2 mmol) in THF (40 mL) and after 30 min a cold (−78° C.) solution of the triflate prepared above in THF (90 mL). The reaction mixture was stirred at −78° C. for 2 h and then poured into cold (−10° C.) sat. aq. NH4Cl (300 mL), diluted with Et2O (300 mL) and layers separated. Aqueous layer was further extracted with EtOAc (2×150 mL), combined extract dried (Na2SO4) and concentrated. Silica gel chromatography with hexanes and hexanes/EtOAc (10:1) as eluents yielded the titled compound 59 as colorless oil (1.33 g; 31% for 2 steps).

1. temperaturecooled to −78° C
2. stirringThe reaction mixture was stirred at −78° C. for 2 h
3. customseparated
4. extractionAqueous layer was further extracted with EtOAc (2×150 mL)
5. extractioncombined extract
6. dry with materialdried (Na2SO4)
7. concentrationconcentrated