反応 #50957

反応方程式

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

ether

→

desired product

収率 93.0%

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

収率 93.0%

溶媒

tetrahydrofuran

反応条件

後処理

1. 1
   その他the reaction is quenched by slow addition of a saturated aqueous solution of ammonium chloride (20 mL) The cooling bath
2. 2
   その他is removed
3. 3
   温度to warm to ambient temperature with vigorous stirring
4. 4
   その他The solvent is removed in vacuo
5. 5
   workup.ADDITIONthe residue diluted with dichloromethane (200 mL)
6. 6
   洗浄The mixture is washed with water (150 mL) and saturated aqueous sodium bicarbonate solution (150 mL), water and brine
7. 7
   抽出The combined aqueous layers are extracted with dichloromethane (200 mL), water (150 mL), NaCl (sat.) (200 mL)
8. 8
   乾燥dried over sodium sulfate
9. 9
   ろ過filtered
10. 10
    濃縮concentrated in vacuo

実験手順

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.

出典