Acetic Acid → tert-butyl 1-((2S)-2-{[(benzyloxy)carbonyl]amino}butanoyl)cyclopropanecarboxylate

Temperature

-78 °C

A solution of diisopropylamine (3.76 mL) in tetrahydrofuran (50 mL) was cooled to −78° C., n-butyllithium-hexane solution (16.56 mL, 1.6 mol/L) was added dropwise and, after the completion of the dropwise addition, the mixture was stirred at −78° C. for 1 hr. Subsequently, a solution of tert-butyl cyclopropanecarboxylate (3.77 g) in tetrahydrofuran (10 mL) was added dropwise, and the mixture was further stirred at −78° C. for 30 min. A solution of benzyl(4S)-4-ethyl-2,5-dioxo-1,3-oxazolidine-3-carboxylate (3.49 g) in tetrahydrofuran (50 mL) was added dropwise at −78° C. for 30 min and the mixture was stirred at −78° C. for 30 min. Acetic acid was added to the reaction mixture at −78° C., water was added and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate=1/0→2/1) to give the title compound as a colorless oil (yield: 1.16 g, 24%).

1. additionn-butyllithium-hexane solution (16.56 mL, 1.6 mol/L) was added dropwise
2. additionafter the completion of the dropwise addition
3. stirringthe mixture was further stirred at −78° C. for 30 min
4. stirringthe mixture was stirred at −78° C. for 30 min
5. extractionthe mixture was extracted with ethyl acetate
6. washThe extract was washed with saturated brine
7. dry with materialdried over anhydrous magnesium sulfate
8. concentrationconcentrated under reduced pressure
9. customThe residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate=1/0→2/1)

ORD record

ord-693ae716b3ea4fdd87cc50ad6fde7e42

Source dataset

uspto-grants-2010_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07834051B2