تفاعل #7758

معادلة التفاعل

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

p-nitrophenyl chloroformate

pyridine

→

desired product

المردود 86.0%

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

المردود 86.0%

المذيبات

dichloromethane

water

ظروف التفاعل

المعالجة

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

الإجراء التجريبي

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.

المصدر