反応 #742261

反応方程式

magnesium

epothilone A

→

epothilone C

収率 80.0%

溶媒

THF

反応条件

後処理

1. 1
   workup.ADDITIONTo a two-necked flask was added
2. 2
   その他The flask was flame-dried under vacuum
3. 3
   温度cooled under argon
4. 4
   その他The stirring suspension was evacuated with low vacuum
5. 5
   workup.ADDITIONthe reaction flask was refilled with argon
6. 6
   その他homogeneous deep green after 1.5 h
7. 7
   その他being consumed
8. 8
   その他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
    その他The volatiles were removed in vacuo
11. 11
    その他the residue was chromatographed two times on silica (25 g)
12. 12
    洗浄eluting with 35% EtOAc/hexanes

実験手順

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.

出典