Acetic Acid → tert-Butyl 4-cyclopropylpiperazine-1-carboxylate

Temperature

60 °C

MeOH (0.3 mL), ((1-ethoxycyclopropyl)oxy)trimethylsilane (2 g, 11.47 mmol) and acetic acid (1.051 mL, 18.35 mmol) were added to a stirred solution of tert-butyl piperazine-1-carboxylate (1.068 g, 5.735 mmol) in THF (40 mL) under nitrogen. Sodium cyanoborohydride (0.541 g, 8.60 mmol) was added portionwise over a period of 10 mins. The resulting mixture was stirred at 60° C. for 24 h. The reaction mixture was evaporated to dryness and mixed with water (80 mL) and 1M HCl (25 mL). This solution was washed with EtOAc (2×50 mL), the aqueous layer was basified with K2CO3, and extracted with EtOAc (2×30 mL). The organic layers were combined, washed with saturated brine (30 mL), dried over MgSO4, filtered and evaporated to afford tert-butyl 4-cyclopropylpiperazine-1-carboxylate (0.792 g, 61.1%) as a colourless oil which crystallised on standing.

1. customThe reaction mixture was evaporated to dryness
2. additionmixed with water (80 mL) and 1M HCl (25 mL)
3. washThis solution was washed with EtOAc (2×50 mL)
4. extractionextracted with EtOAc (2×30 mL)
5. washwashed with saturated brine (30 mL)
6. dry with materialdried over MgSO4
7. filtrationfiltered
8. customevaporated

ORD record

ord-4abb8072c06044d2986baf950fe93620

Source dataset

uspto-grants-2010_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07737149B2