Ethyl Acetate → 4-Isobutyl-dihydro-furan-2-one

Ethyl acetate (0.12 mL, 1.22 mmol) in THF (2 mL) was added dropwise to a stirring solution of lithium bis(trimethylsilyl)amide (1.22 mL of a 1 M solution in THF, 1.22 mmol) at −78° C. under argon. After 20 minutes, 3 (0.21 g, 1.16 mmol) in THF (1 mL) was added, and the mixture was stirred for 2 hours. The mixture was quenched by addition of saturated ammonium chloride solution (3 mL) and allowed to warm to room temperature. The mixture was diluted with ether (20 mL) and dilute hydrochloric acid (15 mL) was added. The organic layer was separated, and the aqueous layer was further extracted with ether (2×10 mL). The combined organic fractions were washed with brine, dried (MgSO4), and the solvent was evaporated under reduced pressure. The residue was chromatographed (SiO2, heptane/ethyl acetate, 99:1) to give the nitro-ester 4 (0.13 g, 41%) as a colorless liquid; Rf(heptane/ethyl acetate, 9:1) 0.32; νmax(film)/cm−1 1731 (C═O), 1547 (NO2), 1375 (NO2); δH (400 MHz; CDCl3): 4.73 (2H, s, CH2NO2), 4.14 (2H, q, J=7.1, CO2CH2Me), 2.58 (2H, s, CH2CO2Et), 2.07 (2H, m), 1.71–1.66 (4H, m), 1.60–1.24 (8H, m), 1.26 (3H, t, J=7.2, CO2CH2Me); m/z (ES+) 270 (M+H, 100%).

1. customThe mixture was quenched by addition of saturated ammonium chloride solution (3 mL)
2. additionThe mixture was diluted with ether (20 mL) and dilute hydrochloric acid (15 mL)
3. additionwas added
4. customThe organic layer was separated
5. extractionthe aqueous layer was further extracted with ether (2×10 mL)
6. washThe combined organic fractions were washed with brine
7. dry with materialdried (MgSO4)
8. customthe solvent was evaporated under reduced pressure
9. customThe residue was chromatographed (SiO2, heptane/ethyl acetate, 99:1)

ORD-Eintrag

ord-8e3b9658f3fb406bbea9378e7cc5ffbe

Quelldatensatz

uspto-grants-2007_03

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07189747B2