Réaction #7757

Équation de réaction

2-[2-(4-Fluorophenyl)acetyl]-4-oxo-pyrazolidine-1-carboxylic acid benzyl ester

ether

→

2-[2-(4-fluorophenyl)acetyl]-4-hydroxy-pyrazolidine-1-carboxylic acid benzyl ester

Rendement 73.0%

Solvants

THF

Conditions de réaction

Traitement

1. 1
   Autrethe reaction is quenched by slow addition of NH4Cl (sat. aq.) (10 mL)
2. 2
   AutreThe cooling bath is then removed
3. 3
   Températureto warm to room temperature with vigorous stirring
4. 4
   AutreThe THF is removed in vacuo
5. 5
   workup.ADDITIONthe residue diluted with water (50 mL)
6. 6
   ExtractionThe mixture is extracted with ethyl acetate (2×100 mL)
7. 7
   Autredried
8. 8
   Filtrationfiltered
9. 9
   Concentrationconcentrated in vacuo
10. 10
    Autreto give a yellow oil which
11. 11
    Autreis purified over silica (1:1 to 1:2 hexane/ethyl acetate to 100% ethyl acetate)
12. 12
    Autreto afford 731 mg (73% yield) as a clear, viscous oil

Mode opératoire

2-[2-(4-Fluorophenyl)acetyl]-4-oxo-pyrazolidine-1-carboxylic acid benzyl ester, 11, (1.0 g, 2.81 mmol) is dissolved in THF (30 mL) and the solution cooled to −78° C. A 5.0 M solution of borane-dimethyl sulfide complex in ether (1.2 mL, 5.61 mmol) is added dropwise. After 1 hour at −78° C., the reaction is quenched by slow addition of NH4Cl (sat. aq.) (10 mL). The cooling bath is then removed, and the mixture allowed to warm to room temperature with vigorous stirring. The THF is removed in vacuo and the residue diluted with water (50 mL). The mixture is extracted with ethyl acetate (2×100 mL), dried, filtered and concentrated in vacuo to give a yellow oil which is purified over silica (1:1 to 1:2 hexane/ethyl acetate to 100% ethyl acetate) to afford 731 mg (73% yield) as a clear, viscous oil.

Source