Benzyl chloroformate → Benzyl 3-oxopiperazine-1-carboxylate

Piperazin-2-one (2.00 g, 20.0 mmol) was dissolved in H2O (10 ml)-1,4-dioxane (10 ml); and NaHCO3 (1.85 g, 22.0 mmol) and benzylchloroformate (3.42 g, 20.0 mmol) was added thereto. After stirring at room temperature for 13 h, the reaction mixture was diluted with H2O and EtOAc. The aqueous layer was extracted with EtOAc and the combined organic layer was washed with brine, dried over MgSO4. The desiccant was removed through filtration and the filtrate was concentrated under reduced pressure to obtain crude 3-Oxo-piperazine-1-carboxylic acid benzyl ester as pale brown oil. This oil was used for the next step without further purification. The crude 3-Oxo-piperazine-1-carboxylic acid benzyl ester was dissolved in DMF (40 ml) and NaH (55% in oil, 1.05 g, 24.0 mmol) and SEMCl (5.01 g, 30.0 mmol) was added thereto at room temperature. After stirring at 50° C. for 18 h, the reaction mixture was diluted with EtOAc. The mixture was washed with H2O and brine, dried over MgSO4. The desiccant was removed through filtration and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/EtOAc=8/2 to 5/5, to obtain the intended compound as a colorless oil.

1. extractionThe aqueous layer was extracted with EtOAc
2. washthe combined organic layer was washed with brine
3. dry with materialdried over MgSO4
4. customThe desiccant was removed through filtration
5. concentrationthe filtrate was concentrated under reduced pressure

ORD record

ord-0755d7b5d468404eacb2014c6d4f4749

Source dataset

uspto-grants-2008_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07410976B2