Sodium cyanoborohydride → Di-tert-butyl pyrazolidine-1,5-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence