1-Chloroethyl chloroformate → Ethyl 1-benzylpiperazine-2-carboxylate

To a solution of ethyl 1,4-dibenzylpiperazine-2-carboxylate (6.76 g, 20 mmol) in 1,2-dichloroethane (20 mL) was added 1-chloroethyl carbonochloridate (3.15 g, 22 mmol) dropwise over a period of 30 minutes at 0° C., and the mixture was stirred at the temperature for another 15 minutes. Then the mixture was stirred at 90° C. for 1 hour. The mixture was concentrated in vacuo, and to the residue was added methanol (15 mL). The mixture was stirred at 70° C. for 1 hour and concentrated in vacuo. The residue was diluted with water and washed with DCM. The aqueous layer was adjusted to pH 9 with NaHCO3 aqueous solution and extracted with DCM. The organic layer was dried over Na2SO4, and concentrated in vacuo to give the title compound as yellow oil (3.06 g, 60%). The compound was characterized by the following spectroscopic data:

1. stirringThen the mixture was stirred at 90° C. for 1 hour
2. concentrationThe mixture was concentrated in vacuo
3. additionto the residue was added methanol (15 mL)
4. stirringThe mixture was stirred at 70° C. for 1 hour
5. concentrationconcentrated in vacuo
6. additionThe residue was diluted with water
7. washwashed with DCM
8. extractionextracted with DCM
9. dry with materialThe organic layer was dried over Na2SO4
10. concentrationconcentrated in vacuo

ORD record

ord-e650976605c34da08bb9a45101cd538c

Source dataset

uspto-grants-2016_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09340538B2