Reacción #1256700

Ecuación de reacción

magnesium

epothilone A

→

epothilone C

Rendimiento 80.0%

Disolventes

THF

Condiciones de reacción

Tratamiento posterior

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

Procedimiento

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.

Fuente