반응 #50957

반응 방정식

4-Oxo-pyrazolidine-1,2-dicarboxylic acid 1-benzyl ester 2-tert-butyl ester

ether

→

desired product

수율 93.0%

4-hydroxypyrazolidine-1,2-dicarboxylic acid 1-benzyl ester 2-tert-butyl ester

수율 93.0%

용매

tetrahydrofuran

반응 조건

후처리

1. 1
   기타the reaction is quenched by slow addition of a saturated aqueous solution of ammonium chloride (20 mL) The cooling bath
2. 2
   기타is removed
3. 3
   온도to warm to ambient temperature with vigorous stirring
4. 4
   기타The solvent is removed in vacuo
5. 5
   workup.ADDITIONthe residue diluted with dichloromethane (200 mL)
6. 6
   세척The mixture is washed with water (150 mL) and saturated aqueous sodium bicarbonate solution (150 mL), water and brine
7. 7
   추출The combined aqueous layers are extracted with dichloromethane (200 mL), water (150 mL), NaCl (sat.) (200 mL)
8. 8
   건조dried over sodium sulfate
9. 9
   여과filtered
10. 10
    농축concentrated in vacuo

실험 절차

4-Oxo-pyrazolidine-1,2-dicarboxylic acid 1-benzyl ester 2-tert-butyl ester, 27, (5.0 g, 15.6 mmol) is dissolved in tetrahydrofuran (150 mL) and the solution cooled to −78° C. A 5.0 M solution of borane-dimethyl sulfide complex in ether (6.24 mL, 31.2 mmol) is added dropwise via syringe. After 40 minutes at −78° C., the reaction is quenched by slow addition of a saturated aqueous solution of ammonium chloride (20 mL) The cooling bath is removed, and the mixture allowed to warm to ambient temperature with vigorous stirring. The solvent is removed in vacuo and the residue diluted with dichloromethane (200 mL). The mixture is washed with water (150 mL) and saturated aqueous sodium bicarbonate solution (150 mL), water and brine. The combined aqueous layers are extracted with dichloromethane (200 mL), water (150 mL), NaCl (sat.) (200 mL), dried over sodium sulfate, filtered and concentrated in vacuo to afford 4.66 g (93% yield) of the desired product as a clear, viscous oil.

출처