Benzyloxycarbonylglycine → 4-Benzyloxycarbonyl-1,2,3,4-tetrahydropyrazin-2-one

To a solution of N-benzyloxycarbonylglycine (10.5 g) and 2,2-diethoxyethylamine (7.33 g) in acetonitrile (50 ml) was added WSC hydrochloride (10.5 g) under ice-cooling, and the mixture was stirred at room temperature for 2 hours. The reaction solution was concentrated, and to the residue were added ethyl acetate and dilute hydrochloric acid. The organic layer was separated, washed with saturated and saturated brine, dried (MgSO4) and concentrated. To the residue were added p-toluenesulfonic acid (951 mg) and toluene (150 ml), and the mixture was refluxed for 30 minutes. The mixture was cooled, and to the reaction solution was added ethyl acetate. The mixture was washed with saturated sodium bicarbonate solution and saturated brine, dried (MgSO4) and concentrated. The resulting crystals were filtered, washed with ether and dried to give colorless crystals of the title compound (7.37 g).

1. temperaturecooling
2. concentrationThe reaction solution was concentrated
3. additionto the residue were added ethyl acetate and dilute hydrochloric acid
4. customThe organic layer was separated
5. washwashed with saturated and saturated brine
6. dry with materialdried (MgSO4)
7. concentrationconcentrated
8. additionTo the residue were added p-toluenesulfonic acid (951 mg) and toluene (150 ml)
9. temperaturethe mixture was refluxed for 30 minutes
10. temperatureThe mixture was cooled
11. additionto the reaction solution was added ethyl acetate
12. washThe mixture was washed with saturated sodium bicarbonate solution and saturated brine
13. dry with materialdried (MgSO4)
14. concentrationconcentrated
15. filtrationThe resulting crystals were filtered
16. washwashed with ether
17. customdried

ORD record

ord-bc543da1ac2c485f8f9a6daca5b9a295

Source dataset

uspto-grants-2004_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06680312B2