Allyl bromide → Methyl 2-(2-oxopyrrolidin-1-yl)pent-4-enoate

Temperatur

-78 °C

Step A (1): To a solution of the methyl 2-(2-oxopyrrolidin-1-yl)acetate (15 g, 95.5 mmol, TCI-America) in THF (600 mL) at −78° C. was added n-BuLi (42.0 mL, 105 mmol, 2.5 M in hexane, Aldrich). After 10 min, allyl bromide (9.7 mL, 115 mmol, Aldrich) was added. The mixture was stirred at −78° C. for 1 h and warmed to room temperature over 2 h. The reaction was then quenched with saturated ammonium chloride. After 15 min the mixture was extracted with EtOAc (3×200 mL). The combined organic layers were dried with Na2SO4 and concentrated in vacuo. The residue was purified by silica gel chromatography (20-80% EtOAc/hexanes linear gradient) to afford methyl 2-(2-oxopyrrolidin-1-yl)pent-4-enoate 4.0 g (21% yield) as pale yellow oil: LC-MS (M+H)+=198.2; 1H NMR (400 MHz, CDCl3) δ 5.67-5.69 (m, 1H), 5.04-5.14 (m, 2H), 4.88 (dd, J=10.70, 5.16 Hz, 1H), 3.70 (s, 3H), 3.44-3.69 (m, 1H), 3.34-3.37 (m, 1H), 2.68-2.75 (m, 1H), 2.36-2.46 (m, 3H), 1.94-2.07 (m, 2H).

1. temperaturewarmed to room temperature over 2 h
2. customThe reaction was then quenched with saturated ammonium chloride
3. extractionAfter 15 min the mixture was extracted with EtOAc (3×200 mL)
4. dry with materialThe combined organic layers were dried with Na2SO4
5. concentrationconcentrated in vacuo
6. customThe residue was purified by silica gel chromatography (20-80% EtOAc/hexanes linear gradient)

ORD-Eintrag

ord-e133cc18c65c49ac9f0d8759a9655bdc

Quelldatensatz

uspto-grants-2008_03

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07338974B2