Allyl bromide → (2S,4R)-1-tert-butyl 2-ethyl 4-allyl-5-oxopyrrolidine-1,2-dicarboxylate

Temperatur

-78 °C

To a solution of HMDS in anhydrous THF (200 mL) was added dropwise 2.5 M n-BuLi in hexane (130 mL) and the mixture was stirred at −78° C. for 1 hr. To a solution of (S)-1-tert-butyl 2-ethyl 5-oxopyrrolidine-1,2-dicarboxylate (8.0 g, 0.311 mol) in anhydrous THF (1600 mL) stirred at −78° C. was added lithium hexamethyldisilazide in THF. After the reaction mixture was stirred at −78° C. for 1 hr, 3-bromopropene (38.47 g, 0.318 mol) in THF (200 mL) was added and stirring was continued for 2 hr. The reaction mixture was quenched with saturated ammonium chloride solution (600 mL) at −78° C. and extracted with EtOAc (3×500 mL). The combined organic layers were dried over Na2SO4, filtered and evaporated to dryness. The crude product was separated by column chromatography to afford (2S,4R)-1-tert-butyl 2-ethyl 4-allyl-5-oxopyrrolidine-1,2-dicarboxylate (15 g, 16%).

1. stirringAfter the reaction mixture was stirred at −78° C. for 1 hr
2. stirringstirring
3. waitwas continued for 2 hr
4. customThe reaction mixture was quenched with saturated ammonium chloride solution (600 mL) at −78° C.
5. extractionextracted with EtOAc (3×500 mL)
6. dry with materialThe combined organic layers were dried over Na2SO4
7. filtrationfiltered
8. customevaporated to dryness
9. customThe crude product was separated by column chromatography

ORD-Eintrag

ord-a29b6dc17b924518a0900095316ea890

Quelldatensatz

uspto-grants-2013_11

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08580823B2