反应详情

温度

25 °C

Di-tert-butyl 4,5-dihydropyrazole-1,5-dicarboxylate (12.65 g, 46.8 mmol) was dissolved in acetic acid (69.2 ml), and the solution was cooled in a water bath. Sodium cyanoborohydride (5.88 g, 94 mmol) was added portionwise under N2. The reaction was stirred at 25° C. for 5 hrs. The solvent was then removed under reduced pressure to give a residue. The residue was diluted with EtOAc (150 mL), and Na2CO3 (sat.) (100 mL) was cautiously added to the solution. The layers were separated and the aq. solution was extracted with EtOAc (2×30 mL), and the organics were dried over Na2SO4. The solvent was removed under reduced pressure to give the crude product di-tert-butyl pyrazolidine-1,5-dicarboxylate (12.74 g) as light yellow oil, which was used directly in the next step.

1. temperaturethe solution was cooled in a water bath
2. customThe solvent was then removed under reduced pressure
3. customto give a residue
4. additionwas cautiously added to the solution
5. customThe layers were separated
6. extractionthe aq. solution was extracted with EtOAc (2×30 mL)
7. dry with materialthe organics were dried over Na2SO4
8. customThe solvent was removed under reduced pressure