反应 #7758

反应方程式

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

p-nitrophenyl chloroformate

pyridine

→

desired product

收率 86.0%

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

收率 86.0%

溶剂

dichloromethane

water

反应条件

后处理

1. 1
   workup.STIRRINGStirring
2. 2
   workup.STIRRINGby stirring at room temperature for 12 hours
3. 3
   萃取extracted with dichloromethane (40 mL)
4. 4
   洗涤The organic layer is washed with 0.5 N NaOH (2×40 mL)
5. 5
   萃取The combined aqueous layers are back-extracted
6. 6
   萃取extracted with dichloromethane (30 mL)
7. 7
   洗涤The combined organic layers are washed with brine (30 mL)
8. 8
   其他dried
9. 9
   过滤filtered
10. 10
    浓缩concentrated in vacuo
11. 11
    其他The crude material is purified over silica (3:1 to 2:1 to 1:1 hexane/ethyl acetate)

实验过程

2-[2-(4-Fluorophenyl)acetyl]-4-hydroxy-pyrazolidine-1-carboxylic acid benzyl ester, 38, (366 mg, 1.02 mmol) is dissolved in dichloromethane (10 mL). The solution is cooled to 0° C. and p-nitrophenyl chloroformate (411 mg, 2.04 mmol) is added in one portion. The solution is stirred at 0° C., and pyridine (198 μL, 2.45 mmol) added. Stirring is continued at 0° C. for 1 hour followed by stirring at room temperature for 12 hours. The reaction is diluted with water (40 mL) and extracted with dichloromethane (40 mL). The organic layer is washed with 0.5 N NaOH (2×40 mL). The combined aqueous layers are back-extracted extracted with dichloromethane (30 mL). The combined organic layers are washed with brine (30 mL), dried, filtered, and concentrated in vacuo. The crude material is purified over silica (3:1 to 2:1 to 1:1 hexane/ethyl acetate) to afford 462 mg (86% yield) of the desired product as a white foam.

来源