反应 #1256700

反应方程式

magnesium

epothilone A

→

epothilone C

收率 80.0%

溶剂

THF

反应条件

后处理

1. 1
   workup.ADDITIONTo a two-necked flask was added
2. 2
   其他The flask was flame-dried under vacuum
3. 3
   温度cooled under argon
4. 4
   其他The stirring suspension was evacuated with low vacuum
5. 5
   workup.ADDITIONthe reaction flask was refilled with argon
6. 6
   其他homogeneous deep green after 1.5 h
7. 7
   其他being consumed
8. 8
   其他An aliquot (3.5 mL, 0.70 mmol, 3.5 eq) was removed
9. 9
   温度The reaction mixture was warmed to room temperature
10. 10
    其他The volatiles were removed in vacuo
11. 11
    其他the residue was chromatographed two times on silica (25 g)
12. 12
    洗涤eluting with 35% EtOAc/hexanes

实验过程

To a two-necked flask was added chopped pieces of magnesium turnings (24 mg, 1.0 mmol). The flask was flame-dried under vacuum and cooled under argon. Bis (cyclopentadienyl)titanium dichloride (250 mg, 1.0 mmol) was added followed by anhydrous THF (5 mL). The stirring suspension was evacuated with low vacuum, and the reaction flask was refilled with argon. The red suspension became dark, turning a homogeneous deep green after 1.5 h with nearly all the magnesium metal being consumed. An aliquot (3.5 mL, 0.70 mmol, 3.5 eq) was removed and cooled to −78° C. under argon. To this solution was added epothilone A (99 mg, 0.20 mmol, 1.0 eq). The reaction mixture was warmed to room temperature and stirred for 15 min. The volatiles were removed in vacuo and the residue was chromatographed two times on silica (25 g), eluting with 35% EtOAc/hexanes to give 76 mg (80%) of epothilone C as a pale yellow viscous oil.

来源