反应详情

温度

-10 °C

At -50° C., 200 mL of MeOH were added to a solution of the enol acetate of Step 3 (214 g, approx. 1.04 mol) in 800 mL of acetone. At -78° C., ozone was bubbled through this solution for 7 h (or until the excess of O3 produced a green color). The excess of O3 was blown away by a stream of N2 and a solution of triphenylphosphine (327 g, 1.25 mol) in 1 L of acetone was then added, slowly at -78° C. The temperature was slowly raised to -10° C. over 30 min., 1N HCl (700 mL) was slowly added, and the mixture was stirred at 3° C. for 16 h. The organic solvent were evaporated, 500 mL of EtOAc were added and the mixture was alkalinized with an excess of NaHCO3 (approx. 270 g). The aqueous phase was washed with EtOAc (2×1 L) and the organic layers were reextracted with 1 L of saturated NaHCO3 by agitation over 2 h. The combined aqueous extracts were then acidified with conc. HCl and extracted with EtOAc. The extract was dried over Na2SO4, the solvent was evaporated and the acetic acid was co-evaporated with toluene to yield 139.6 g of the title compound (75% for Steps 3 and 4) as a white solid.

1. customAt -78° C., ozone was bubbled through this solution for 7 h (or until the excess of O3
2. customproduced a green color)
3. customThe organic solvent were evaporated
4. addition500 mL of EtOAc were added
5. washThe aqueous phase was washed with EtOAc (2×1 L)
6. waitthe organic layers were reextracted with 1 L of saturated NaHCO3 by agitation over 2 h
7. extractionextracted with EtOAc
8. dry with materialThe extract was dried over Na2SO4
9. customthe solvent was evaporated