반응 #7758

반응 방정식

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

p-nitrophenyl chloroformate

pyridine

→

desired product

수율 86.0%

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

수율 86.0%

용매

dichloromethane

water

반응 조건

후처리

1. 1
   workup.STIRRINGStirring
2. 2
   workup.STIRRINGby stirring at room temperature for 12 hours
3. 3
   추출extracted with dichloromethane (40 mL)
4. 4
   세척The organic layer is washed with 0.5 N NaOH (2×40 mL)
5. 5
   추출The combined aqueous layers are back-extracted
6. 6
   추출extracted with dichloromethane (30 mL)
7. 7
   세척The combined organic layers are washed with brine (30 mL)
8. 8
   기타dried
9. 9
   여과filtered
10. 10
    농축concentrated in vacuo
11. 11
    기타The crude material is purified over silica (3:1 to 2:1 to 1:1 hexane/ethyl acetate)

실험 절차

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.

출처