Реакция #7750

Уравнение реакции

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

ether

→

desired product

Выход 93.0%

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

Выход 93.0%

Растворители

tetrahydrofuran

Условия реакции

Обработка

1. 1
   Другоеthe reaction is quenched by slow addition of a saturated aqueous solution of ammonium chloride (20 mL)
2. 2
   ДругоеThe cooling bath is removed
3. 3
   Температураto warm to ambient temperature with vigorous stirring
4. 4
   ДругоеThe solvent is removed in vacuo
5. 5
   workup.ADDITIONthe residue diluted with dichloromethane (200 mL)
6. 6
   ПромывкаThe mixture is washed with water (150 mL) and saturated aqueous sodium bicarbonate solution (150 mL), water and brine
7. 7
   ЭкстракцияThe combined aqueous layers are extracted with dichloromethane (200 mL), water (150 mL), NaCl (sat.) (200 mL)
8. 8
   Сушкаdried over sodium sulfate
9. 9
   Фильтрацияfiltered
10. 10
    Концентрированиеconcentrated in vacuo

Методика

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.

Источник